HP 5335A Timer / Counter - Anything i should know?

[max_torque]

After messing around with various projects that require accurate (or at least repeatable) timing, i've finally bitten the bullet and brought a "proper"  timer counter, the classic (very classic.... ;-) HP 5335A.  Unfortunately it doesn't have the high precision oscillator option, but i was wondering if there are any tweaks / tips / or things i should be aware of with this meter?

It seems quite a popular meter, so i immagine there are quite a few in hobbiest / Amature hands etc!



It ran out of calibration at the end of last year, but i guess now that it's nearly 28 years old it'll be fairly stable??

[Vgkid]

Nothing really bad with them, unless you fry the input assy. The only issue (mine will refuse to read input if chanels are switched during use,yet passes self check for both ). The opt 10 can be found on ebay if you want one.
Also you have the front display cover plastic grrrr. Mine doesnt.

[babysitter]

Having serviced its little brother 5334A just today:

Look for burned resistors at the input, that is the main thing. Mine had a burned 50 Ohm Termination on Channel A, which I didnt realize that the only time I used the internal termination I was using channel B. Also, the first series Resistor in the Arming path was burned, too, but it works again.

The termination was fixed before, the original ckt is 2 100 Ohm in parallel which were dark burned, and another pair of new 100 Ohm resistors was stacked on top without removing the first ones ,I fixed it by replacing the stacks with a 56 Ohm and a 402 Ohm O0 The Arm path was a 619 Ohm resistor, replaced with a 620 Ohm type measuring 619 - not that I expect any effect. All working well now. 

Mine was without Option 010 also, now wonder as the price was below a 10811 which is the thing you might want for the 5335 also. But a cheap OCXO from ebay went in with ugly connections, doing a good job, too.

[max_torque]

Yeah, i noticed the 5v max input limit in the manual when 50Ohm termination is selected, irrespective of frequency or attenuation.  Could imagine that it would be pretty easy to accidentally smoke that, especially as otherwise you've got 250V to play with!!

Mines Ex-MIL, must have been de-mobbed quite recently as the cal sticker says DEC13 for recal, so only about 6 months ago.  Will probably pop the lid off for a look around (check those 50Ohmers!) and perhaps any caps etc that are looking crispy (build date on mine is WK26 1986, so it's getting on a bit).  I suspect it's been rack mounted in a fixed system assy, because it's in excellent condition, with few scratches, all it's buttons, and ALL the BNC's are undamaged with little wear. THE HPIB connector also looks immaculate and dust/dirt free, so i suspect it's been remote controlled for a lot of it's life (which would also explain why it's only just been de-mobbed if it's been part of an active system, and hence difficult to just 'upgrade' unlike a unit used for bench test etc.

Will have to keep an eye out for the Oven Oscillator on ebay, and i'd love to find a cheap HPIB -> USB adaptor (or knock one up with a suitable micro controller ;-)

[babysitter]

I employ a Prologix USB Adapter for my GPIB Stuff.

Into my counter went a C-MAC STP2390C OCXO, free-wired to the Option 010 Connector (Not 10811 Layout); looking ugly but seems to work fine, tonight it is busy with a TIC Measurement Rb against its own reference output. The 5334 both A and B have a quite unsatisfying internal oscillator. Counter plus OCXO were ebay for less than a single 10811 or 10544

(Which i think will fit yours directly. Take care, several different versions of the 10811 exist, some with relaxed specs.)

Next intermediate goal: Hack together a C channel option...

[Dr. Frank]

After messing around with various projects that require accurate (or at least repeatable) timing, i've finally bitten the bullet and brought a "proper"  timer counter, the classic (very classic.... ;-) HP 5335A.  Unfortunately it doesn't have the high precision oscillator option, but i was wondering if there are any tweaks / tips / or things i should be aware of with this meter?

It seems quite a popular meter, so i immagine there are quite a few in hobbiest / Amature hands etc!



It ran out of calibration at the end of last year, but i guess now that it's nearly 28 years old it'll be fairly stable??

Nope, the standard XTAL is crappy and will stay crappy forever. (crappy means unstable)
The calibration therefore is near to meaningless.

An ordinary XTAL is good for 1e-6 stability over a day or so , short term stability also not very good.
Temperature coefficient is also bad.

Contrasting that, this instrument resolves about 1ns or 9 digits/sec, therefore an OCXO is required.

Try to get an option 010 =  10811-60111, that is the cheapest one of that series, but after 20+ years, rock stable, i.e. < 1e-10/ day / month.
Should sell for less than 100$. Or get an external GPSDO.

Well, a picture of the interior of your counter, and most important the revision numbers of the PCBs and the complete ser-No prefix of your counter would be great (see below).
Do you already have the opt. 040, that's the GPIB steered front end?
And what about opt. 030, C-Input?

There exist mainly two versions, the elder one covered by manual 05335-90005 (1980, ser prefix  #2024) or  05335-90021 (1983, #2224), both online, and the newer version covered by 05335-90044 (1994, #3145A) (available by Artek, I think).
I think, they made severe changes in between, regarding the counting chains. Not sure, anyhow.

Oh yes, and get HP journal 1980-09.

Mine is 2820Axxxx, from 1988, and it contains newer motherboard and opt. 010, 030 (new), 040.

Well I tweaked  one electrolytic, which controls the manual gate time, so that I could measure up to 12.5secs, (instead of only 1s), to get 10 digits from the front panel.
Otherwise, GPIB control would do the job, up to 11 digits.

Anyhow, it's a very nice, versatile  instrument, but you also need now a GPSDO to enter time-nuts world,as mentioned before
Thunderbolt and Lady Heather make a nice couple..

Frank

[babysitter]

My intention changed over time as I have quite good external 10 MHz available:

I first was thinking about ovenizing it with a QH40A from Kuhne elektronik which is a heater module for (HC49) crystals.
Then I thought about replacing the original ckt with a TCXO, but finally i have embedded this OCXO in it.

Consider using the ext. Ref Port: Either you could feed a good external 10 MHz source into the device, or put your best source inside and get it out of the Ref Port for other purposes. Put some planning into it.

Glad to hear that the 5335 also has a crappy timebase

[Dr. Frank]

Glad to hear that the 5335 also has a crappy timebase

No, my friend! 
Mine already came with the 10811 

[max_torque]

Mines 2626Axxxxx, and only has the 040 'extended HPIB' option fitted (no high speed channel C, although that doesn't matter for what i am going to use it for).  I'll pop the hood and take some pics inside tommorrow.

Funnily enough a GPSDO is something i'd started, but not finished a while back:





;-)

[Vgkid]

It would be interesting to know why they didn't fit the 10811A spec'd oscillators to these units, as opposed to the 10811-6011 oscillators.

[Dr. Frank]

It would be interesting to know why they didn't fit the 10811A spec'd oscillators to these units, as opposed to the 10811-6011 oscillators.

Hu, waddaya mean??

The 10811 OCXO exists in many different versions, i.e. HP10811A/B/D-xxxxx, differently specified (Allan statistics), different pinning, or in a doube oven.

The 5335A, opt. 010 and the 5370B both have the 10811-60111 version, which already is very good... after all those years.

If I find the datasheet, that specifies several of the versions, I'll upload it here.

Here's the document about the various versions:
http://www.leapsecond.com/museum/10811a/90027-1.pdf

Frank

[babysitter]

Glad to hear that the 5335 also has a crappy timebase

No, my friend! 
Mine already came with the 10811 

Well, yours... your equipment I suppose is one of the best cal labs around. And with competent end enthusiastic personnel, not just soe demotivated guy who needs to do it to bring home food 

But I somewhat understand the reasoning behind HPs decision for those designs.

[max_torque]

Here's a few pics of the internals.  Looks like it must have been built some time late in 1987, as most of the iC date codes are mid '87:






















I'm definitely going to be looking for an 10811a to fill the empty slot ;-)

[Wim13]

I got mine 5335a very cheap, because it was totally dead, but cosmetic very good condition

After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.

In my unit there was a 10544 ocxo, whixh is very good, compared to my Rubidium standard.
i also have a 10811, but that unit is worse compared to the 10544.

For precision work i use the rubidium clock, connected to the external clock input.

Also replaced the FAN for a silent computer fan, works very well no fan noise anymore.

[max_torque]

Interesting about the fan replacement, mine i extremely noisy, and seemingly over powerful for the heat generation capability of the unit!  I wonder if being "rack mountable" the fan is spec'd to get relatively "hot" air, rather than the typical 25-30degC air of a typical electronics lab??  A quiet fan would be nice, looks like mine is powered off the unregulated ~25vdc rectified bus.  Fan is 30Vdc rated

Regarding swapping in a OCXO, the manual suggests a jumper wire must be removed to disconnect the original "on pcb" clock source, but where is this wire? (maybe later units don't have it?)  I can find all the components in the original clock source, but it's not immediately obvious (to me ;-) where that jumper is.

Thirdly, are there any affordable GPIB -> USB adaptors, they all seem silly money for what is effectively a parallel to serial converter 

[Wim13]

Replacing the FAN....

Old FAN: Papst 8500N, 110 Volts 34 dB, 61 m3/hour

New FAN, Noctua, NF-R8 12 Volts 17 dB, 53 m3/hour

The unit stays very cool, no problems with temperture.
The uP was getting hot, also in the old situation, so placed a
cooling strip on th uP.

Fore the GPIB i use the Prologic, is also quite expensive, but works very good.
But was already in use for other equipment.
can make your own software on the easy way, as post somewhere above.
i also use Free pascal for that.

[ve7xen]

I have no experience with it, but I've heard this Agilent 82357 clone works reasonably well:

http://www.measuretechnic.com/?product=m82357-usbgpib-interface-alternative-to-agilent-82357b

It can be had for < $100, though still a bit expensive for what it is, it's not too bad a price for such a niche item, assuming it works as advertised.

[AllanMN]

I also just bought one of these too!

I'll post pictures in a day or two. Also, w/o the high stability time base I believe but with the 1.3 GHz option.

Considering a necessary timebase upgrade, for a cheap option (<<$100), the morion mv89a double oven OCXO's for $25-35 on ebay seemed like the best option for possibly (depending it's condition) 10-11/sec stability and even 10-8/year discussed here: http://www.ke5fx.com/Morion_MV89A_IEEE_IFCS_2002.pdf

10E-8 would be quite good enough for me.

The HP 10811 option, from the specs I saw did not seem to be nearly as good, and looked likely $100+.

[babysitter]

You rather have a look at the power supply, the Morion neets lot of juice on the 12V line where the 10811 is only supplying oscillator and oven controller because of its dedicated Heater connector.

[AllanMN]

Well, here's what I got off ebay, a serial prefix 2323A model with option 010, 030 and 040. Typical horror story, the seller shipped with the fan flopping around by the power leads smashing things up a bit. I collected 5 loose parts and identified a couple broken leads.

But, I got the 10811-60111 timebase unexpectedly.

I need to replace the broken off caps and transistors before I'll power on. It was shown working in the listing.

Allan

[max_torque]

Wow, nice to get the precision Osc & high speed channel C options!  Less good about the shoddy shipping and subsequent damage 


The more i see how clean and undamaged my unit is, the more i'm convinced it's lead a sheltered life in some air-conditioned and filtered test system somewhere!

[Thomas]

For a GPIB interface, you should consider this:
http://galvant.ca/shop/gpib-usb-adapter-rev3/
Low cost, $59 on sale now

I got one for my Racal Dana 1992 Universal Counter, haven't really gotten around to testing it properly.
But I get some response on the counter, the REM and ADDR leds light. Just played around in a terminal.

Shows up as a serial port on the computer.

Edit:
Oooh, almost forgot: nice instrument you got there!

[Vgkid]

Well I tweaked  one electrolytic, which controls the manual gate time, so that I could measure up to 12.5secs, (instead of only 1s), to get 10 digits from the front panel.
Otherwise, GPIB control would do the job, up to 11 digits.
Frank

Can you go into detail on this.

[Dr. Frank]

Well I tweaked  one electrolytic, which controls the manual gate time, so that I could measure up to 12.5secs, (instead of only 1s), to get 10 digits from the front panel.
Otherwise, GPIB control would do the job, up to 11 digits.
Frank

Can you go into detail on this.

Change A4C36 from 10µ/10V to 22..47µ/10V. Correct value depends on tolerances in the circuitry, and on the capacitors leakage current.
This will increase "Gate Mode NORM"  time from (20ms..4s) to ca. (50ms..12s), delivering max. 10 digits instead of max. 9 only.

Edit: I assembled a 22µF/10V Ta capacitor for 12.5s max.
In later versions, HP replaced all the tantalums they used before.

[Orange]

Hi,

Attached you will find V1.1 EPROM images. My HP5335 counter was equipped with V1.0 firmware in two ROM sockets, so I split-up the V1.1 from an 27128 into two MCM68764 EPROMS.
Main changes for this firmware are related to the HP-IB section.
This is also a safe upgrade to get rid of the MK36000 time bomb.

Works OK in an 'old' style 5335 with two ROM sockets.

Edit : Beaware of the Channel C prescaled factor; V1.0 has a division ratio of 20. The version here posted requires a div. by 64

[Orange]

Change A4C36 from 10µ/10V to 22..47µ/10V. Correct value depends on tolerances in the circuitry, and on the capacitors leakage current.
This will increase "Gate Mode NORM"  time from (20ms..4s) to ca. (50ms..12s), delivering max. 10 digits instead of max. 9 only.

Nice addition, I noticed that I get 11 digits now when it has to display 10.000002399 for example. It is clever in a way, because it jumps automatically from the
10. 000 000 00 notation to the ones without blanks. HP did now how to write software in the old days 

[Wim13]

Well I tweaked  one electrolytic, which controls the manual gate time, so that I could measure up to 12.5secs, (instead of only 1s), to get 10 digits from the front panel.
Otherwise, GPIB control would do the job, up to 11 digits.
Frank

Can you go into detail on this.

You can do this also by hand, use the manual open/close push button, under gate mode.
if you leave the gate open for hundreds of seconds you get more digits.

[Dr. Frank]

You can do this also by hand, use the manual open/close push button, under gate mode.
if you leave the gate open for hundreds of seconds you get more digits.

That's correct. 100s will give 11 digits resolution, but that's it.
For even longer times, say 1000s, the counter will not output more than 11 digits plus the trailing "1" maybe, neither on the display, nor over the GPIB.

That's a pity, as the counter internally counts and calculates to 20 digits, or so.

[Dr. Frank]

Following a hint from the usual manual storage, the version 1.1 can be identified by the start up message of the GPIB address.
The (additional) decimal point before the address is displayed only for the V1.1

I got a 1988 counter, but 1987 firmware, presumably already the V1.1, although it is still in two EPROMs. Well, now I wonder if I should see 2 decimal points...

Perhaps owner of the old version may take a notice if the GPIB address is completely without decimal points.. I.e. "HP-IB Addr 18" or

"HP-IB Addr. 18"


And what is the "MK 36000 time bomb"?

[Orange]

OK, so I changed the EPROMS from V1.0 to V1.1. Initially done some tests on Channel A  and B, and all seems fine...

Later today I checked Channel C    With a 100MHz signal it displays 320MHz !, 1200MHZ gives 3840MHz on the display !

I presume that the later units have a different division factor for the Channel C board which is compatible with V1.1
I could not find this in the documentation.

So its back to V1.0

[Orange]

And what is the "MK 36000 time bomb"?

My unit had a MK36xxx ROMs. They are notorious for sudden failure. Lots of units of HP and Tektronix have them. If you ever have a unit with them, and the unit does not work while everything else is OK, it might be the dreaded ROM syndrome. Mostek did a bad job with these suckers.
They basically loose their content, also known as ROM rot

 

[Dr. Frank]

Yes sorry, I'm a bit late.
I had to study all the change history in manual 05335-90044, up to Serial Prefix 3154.

V1.1 had been introduced in June 1984, for all instrument with 2424A06001 and above.

V1.1  has one decimal point in the HP-IB string, as shown with my instrument.
V1.0 shows no decimal point in the GP IB string at all.

I already have the newer prescaler  in the C-channel (05335-60034), which divides by 64.
The old prescaler (05335-60009) divided by 20 only, therefore the firmware has to match.

It's not clear, if there exists an intermediate firmware which corrects all the bugs of V1.0, but is made for the old prescaler, i.e. multiplies the result by 20 instead of 64.

The difference may be inside the EPROM A4U22, as 05335-80012 (as in my unit) refers to the new /64  prescaler, and 05335-80006 refers to the old /20 prescaler.
That's change 7 in this manual, and affects prefix 2820, exactly my counter, and also for retrofitting the newer C-channel option 030.


Obviously, I have an intermediate A4 version, 2 EPROMs - but V1.1 and the newer prescaler. Perhaps my instrument had been updated, or the C - Input had been replaced.

I could not find a comprehensive table, which EPROM code refers to which firmware version, and/or to which prescaler.
Frank

[Dr. Frank]

Well, my instrument also needed a new fan, but I bought one from papst again.

In my version, the 110V type had been replaced by a 24VDC / 36CFM one, as shown in the photographs.
It is fed by the unregulated + or - 25V. Got no schematic for that change.

I chose an 8414NGM, 80x80x25mm,58m3/h, and it has 26dB(A) only.

Frank

[Orange]

My unit also has a Papst DC fan, its rated for 18 Volts, but it runs from 24 Volts !

Strange that official diagrams do not include this change. For sure it was build by HP like this.

I could change it for a Sunon Maglev, that should kill the noise 

[Dr. Frank]

My unit also has a Papst DC fan, its rated for 18 Volts, but it runs from 24 Volts !

Strange that official diagrams do not include this change. For sure it was build by HP like this.

I could change it for a Sunon Maglev, that should kill the noise 

This change from 110V to 24V is described in words, but I'm lacking the schematics.
So it was an official change, definitely.

The fan operates from 18 to 28V.

[PE1RKI]

mine also came with the papst rated 18 to 30 volt.
most ic date codes are 1989.
i got it from a danish company going bust for cheap.
but is has no 1300mhz option and no oven 
and thanks so much for the capacitor hint!!!!! 
i modded mine immediately

[Dr. Frank]

OK, so I changed the EPROMS from V1.0 to V1.1. Initially done some tests on Channel A  and B, and all seems fine...

Later today I checked Channel C    With a 100MHz signal it displays 320MHz !, 1200MHZ gives 3840MHz on the display !

I presume that the later units have a different division factor for the Channel C board which is compatible with V1.1
I could not find this in the documentation.

So its back to V1.0

Hi Oranje,

after reviewing all the pictures posted here, I think that max_torque has got the right combination of EPROMs for you.

The 05335-80006 for the elder by-20 scaler, and the 05335-80007 as in my unit.
If his unit displays the decimal point, then it should be the updated V1.1 also, especially as his unit is 2626A.

Perhaps he may read the content of both EPROMs for you and you'd give that try.

Frank

[Orange]

Well that's certainly worth a try.

I find it peculiar that HP never mentioned something about it. It's also a thing to remember if you want to upgrade your counter with a Channel C board.

[Dr. Frank]

Well that's certainly worth a try.

I find it peculiar that HP never mentioned something about it. It's also a thing to remember if you want to upgrade your counter with a Channel C board.

Hm, I got that latest manual ...90044, which really covers EVERYTHING.
The manual changes are described in reverse order, and very complicated to read.
The different schematics stages are missing, so you have to imagine these.

As I got a (very good) copy only, I don't know, how the original manual looks like.

But anyhow, I think the status is clear now.

Would be interesting, if you get the content and succeed to update correctly.
V1.0 has really many annoying GPIB related and function bugs.

Good luck.
Frank

[max_torque]

This is turning into quite an interesting thread! ;-)

Yes, my unit is V1.1 and displays decimal point on boot.  I'll try and upload the proms when i get a second 


I think i will install the fan mod too.  Mine is running from the DC bus, but boy is it noisy!  It's like someone doing the hoovering in the room 


Also, i notice the GPIB board "A7" is completely seperate from the logic board "A4" and consists of a GPIB driver, driven by some parallel data lines for address and data etc.  A nice little project would be to replace this pcb with a modern microcontroller with a direct USB output, to a USB socket on the front panel (probably on the right hand side)  That would neatly avoid all the messing around with GPIB->USB convertors etc!

If i find the time i might scope out some of the signals, however, assuming the driver IC on A7 is "dumb" then we should have TTL level GPIB protocol on the A7xA4 connector?

[Dr. Frank]

This is turning into quite an interesting thread! ;-)

Yes, my unit is V1.1 and displays decimal point on boot.  I'll try and upload the proms when i get a second 


I think i will install the fan mod too.  Mine is running from the DC bus, but boy is it noisy!  It's like someone doing the hoovering in the room 


Also, i notice the GPIB board "A7" is completely seperate from the logic board "A4" and consists of a GPIB driver, driven by some parallel data lines for address and data etc.  A nice little project would be to replace this pcb with a modern microcontroller with a direct USB output, to a USB socket on the front panel (probably on the right hand side)  That would neatly avoid all the messing around with GPIB->USB convertors etc!

If i find the time i might scope out some of the signals, however, assuming the driver IC on A7 is "dumb" then we should have TTL level GPIB protocol on the A7xA4 connector?

Hope your Eprommer can handle those strange EPROMs, they have another pinning than the 2764s.
So I can't read mine..

A7U1 is not a dumb GPIB driver, it's the 68488 GPIB controller, so I assume it contains also several timer, registers and perhaps a small state machine.
Edit: Yes, it's confirmed. datasheet still is online, and the chip contains a lot more of intelligence. Especially all those GPIB handshake signals and registers, DMA controller, and GPIB-488 command parser are covered.
Frank

[max_torque]

No, my EEPROMMER isn't "Old skool" enough to deal with the MCM68764 chip!  I'll have to knock up something with a micro to read them............

Ok, so if the GPIB board does have it's own intelligence driver, that means the interface between it and the main processor on A4 is even more likely to be fairly simple?

[Dr. Frank]

Ok, so if the GPIB board does have it's own intelligence driver, that means the interface between it and the main processor on A4 is even more likely to be fairly simple?

Well, the interface maybe simple, but the traffic on it is quite complicated as the 6802 µP has to program all that stuff inside the GPIB controller.
I see no chance to simply interface at that point, either.

Frank

[Wim13]

My 5335, serialnumber starts with 2032A, and has two NMOS roms type 2364
And also my advance (e)prom programmer has no option for these.

If you want, you have to make a conversion tool, it does not differ very much from a 2764,
so it is not difficult to make because you have only to read the 2364
I did that before to convert from some old TMS 2564 to 2764

I found with google some already designed conversion tools.

2364 Pinout compared to 2764

                                                2764
                                            +----\/----+
          2364                         Vpp        Vcc
      +- --\/----+                    A12         P
 A7 | 1       24| Vcc              A7           nc
 A6 | 2       23| A8               A6           A8
 A5 | 3       22| A9               A5           A9
 A4 | 4       21| A12             A4         A11
 A3 | 5       20| /CS              A3         /OE
 A2 | 6       19| A10             A2         A10
 A1 | 7       18| A11             A1         /CE
 A0 | 8       17| D7               A0          D7
 D0 | 9       16| D6               D0          D6
 D1 |10      15| D5               D1          D5
 D2 |11      14| D4               D2          D4
Vss |12      13| D3               Vss         D3
      +----------+                     +----------+

[Zucca]

Very happy to find such a post here.

Yes I´m on board too, I made yesterday a jump in the dark by buying this puppy:

http://www.ebay.com/itm/HP-5335A-Frequency-Counter-/181420545057?nma=true&si=q%252B7%252BHm8nU5AXQNl3C3Cf3Ut7vl4%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

Seller had 0% review in ebay....  When I will open this up I am worried to find dead animals inside. My be it was used by EE terrorists in the past. Keep you posted.

Can´t wait to tune it up...

Sorry for the slightly out of topic question... but which EEPROM reader to you suggest? I am missing such a device on my bench.

PS: I got water in my mouth for a rubudium 10MHz bomb now.

[orin]

My unit also has a Papst DC fan, its rated for 18 Volts, but it runs from 24 Volts !

Strange that official diagrams do not include this change. For sure it was build by HP like this.

I could change it for a Sunon Maglev, that should kill the noise 

This change from 110V to 24V is described in words, but I'm lacking the schematics.
So it was an official change, definitely.

The fan operates from 18 to 28V.

Replying to an out of date post, but since I just replaced my fan and fixed another problem:

The change was described in a service note (attached).

I strongly recommend replacing the relay socket and implementing the wiring change in the service note or one day, you'll turn it on, the fan will run, but you will get no display.  The relay socket is part #27E213, PB806-ND from Digi-Key.  The socket contacts fatigue from running too hot/heat cycling and eventually, when cool, the contacts for the 5V supply don't make contact any more.  In my case, I got strange behavior for while before it finally wouldn't turn on.

I have put an 8414NGM in my unit too, but be aware that it cannot handle the same static pressure that the 8124G can.  Compare the charts:

http://elcodis.com/parts/452608/8124G.html#datasheet
http://img.ebmpapst.com/products/datasheets/DC-axial-fan-8414NGM-ENG.pdf

I have no idea what is required in terms of static pressure vs. air flow for the 5335A.  All I know is that the original parts list specified 32CFM air flow for the 120V fan.

[1980s_john]

I got mine 5335a very cheap, because it was totally dead, but cosmetic very good condition

After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.

Thanks for the tip, my 5335A is similarly dead (well the fan comes on and that's it), all the main PSU outputs read close to 0V with the regulator inputs are at +/- 12V and +/- 24V. I am used to shorted tants in IBM PCs, where due to the high current available the results are a little more spectacular 

Regards,
John

[orin]

I got mine 5335a very cheap, because it was totally dead, but cosmetic very good condition

After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.

Thanks for the tip, my 5335A is similarly dead (well the fan comes on and that's it), all the main PSU outputs read close to 0V with the regulator inputs are at +/- 12V and +/- 24V. I am used to shorted tants in IBM PCs, where due to the high current available the results are a little more spectacular 

Regards,
John

If you have the DC fan, it's likely that the contacts on the relay socket have opened up.  See the service note in my post above.  The relay socket is a 27E213, Digikey part number PB806-ND.  If it is the relay socket and you do the modification in the service note, you probably don't need a new relay; I'm still using my original relay.  Anyone with a 5335A should make sure that this modification is done and switch to a DC fan.  The 5V supply relay socket contacts get hot, fatigue and eventually, when they cool down, don't make contact with the relay any more.

You can check if it's the relay socket by following the input for the 5V supply from the fuse and across the relay.  If the 5V supply is down, the other supplies don't come up either.  You might try reseating the relay (carefully, the top tends to come off the relay).  That worked for me for a while.

The relay itself is pretty much unobtainium - it's a 6PST NO with 5A rated contacts.  It should easily carry the 2A or so that I measured on the 5V supply, but the socket contacts don't.  The modification uses the contacts that were originally used for the AC fan in parallel with the original contacts for the 5V supply so the DC fan modification is absolutely required.

There is a similar relay available with 2A contacts.  I have one but haven't tried it yet.  I'm sticking with the original relay while it's working.

Orin.

[1980s_john]

After lot of research, all of the tantal C's on the input board were totally short circuit. The blue bulbs in the picture.
The power supply is short protected, so replaced all tantals, and the unit was up and running, and in good condition.

Thanks for the tip, my 5335A is similarly dead (well the fan comes on and that's it), all the main PSU outputs read close to 0V with the regulator inputs are at +/- 12V and +/- 24V.

I finally got around to working on my 5335A, the service manual is a must have. The input board is the 'A3 Amplifier Buffer assembly (05335-60003)', I replaced the big blue tant caps (22uF) with new 35V parts. It now powers up and the front panel / processor / display appear to work, but it is not working as the PSU voltages are still not right. I get:

-15V output = +0.7V
+5V = 5.07V
+10V=10.0V
+15V=15.7V
-5.2V=+0.6V
+3V=3.0V

So problems with the -15V and -5.2V rails, which appear to be independent. Any tips please?

Regards,
John

[1980s_john]

If you have the DC fan, it's likely that the contacts on the relay socket have opened up.  See the service note in my post above.  The relay socket is a 27E213, Digikey part number PB806-ND.  If it is the relay socket and you do the modification in the service note, you probably don't need a new relay; I'm still using my original relay.  Anyone with a 5335A should make sure that this modification is done and switch to a DC fan.  The 5V supply relay socket contacts get hot, fatigue and eventually, when they cool down, don't make contact with the relay any more.

Thanks, my relay seems to be OK. However removing it shows a black heat mark on the socket, presumably where the 5V passes through. Thanks for the service note, I must give it a go.

The HP part for the relay is 0490-1172. Printed on the side is the code R10A-E1-X6-V430, and a date code 7923. ebay shows loads of R10-E1-X6-V430, is the R10 2A relay and the R10A 5A then?

Regards,
John

[orin]

If you have the DC fan, it's likely that the contacts on the relay socket have opened up.  See the service note in my post above.  The relay socket is a 27E213, Digikey part number PB806-ND.  If it is the relay socket and you do the modification in the service note, you probably don't need a new relay; I'm still using my original relay.  Anyone with a 5335A should make sure that this modification is done and switch to a DC fan.  The 5V supply relay socket contacts get hot, fatigue and eventually, when they cool down, don't make contact with the relay any more.

Thanks, my relay seems to be OK. However removing it shows a black heat mark on the socket, presumably where the 5V passes through. Thanks for the service note, I must give it a go.

The HP part for the relay is 0490-1172. Printed on the side is the code R10A-E1-X6-V430, and a date code 7923. ebay shows loads of R10-E1-X6-V430, is the R10 2A relay and the R10A 5A then?

Regards,
John

Sorry, R10-E1-X6-V430 won't work.  It is a 6PDT relay and wouldn't even fit the socket (18 contact pins) whereas the original R10A is a 6PST relay (12 contact pins).

The V23154-D0721-B112 is a 6PST 2A relay that might work - the contact arrangement appears to be correct.  Onlinecomponents.com have a couple available, but $50 each.  You'd definitely need the service note modification as I measured the current on the 5V supply at up to 2.2A.

Orin.

[Wim13]

I finally got around to working on my 5335A, the service manual is a must have. The input board is the 'A3 Amplifier Buffer assembly (05335-60003)', I replaced the big blue tant caps (22uF) with new 35V parts. It now powers up and the front panel / processor / display appear to work, but it is not working as the PSU voltages are still not right. I get:

-15V output = +0.7V
+5V = 5.07V
+10V=10.0V
+15V=15.7V
-5.2V=+0.6V
+3V=3.0V

So problems with the -15V and -5.2V rails, which appear to be independent. Any tips please?

Regards,
John

Replace the -15V regulator by a 7915, the -5 volts is depended on the -15V.
because of the op-amp that is in line with the -5 V

[1980s_john]

Replace the -15V regulator by a 7915, the -5 volts is depended on the -15V.
because of the op-amp that is in line with the -5 V.

Thanks, I've started removing / unplugging boards to get to the A1 Power Supply board. With A3/A6/A9 removed, the unit now brings up -15V and -5V but only intermittently  . It may be a failing -15V regulator, I see someone has been there before me and a 7915 is already fitted.

I will try and measure the max. current available on -15V and -5V with no boards plugged in, then replace the 7915 and measure max current again. I will replace the fan with a 24V one and rewire the 5V at the same time (currently have a 115V fan fitted and working fine).

No more progress for a few weeks, I wish everyone a Happy Easter!

Regards,
John

[Vgkid]

Does the fan blow into the unit, or out?
Also is it safe to go with a 32cfm fan(26db), or go with the updated 36cfm(29db) fan. Mines starting to get loud.

[PE1RKI]

mine blows out.
i dont mind the noise unless the fan is breaking down or rattling, then i will replace it with a simular one.

[Vgkid]

Thanks, it is starting to get loud. I will most likely get a new one, and fix the old one.
Also, can someone take a picture of the standby led mounting. I just have a hole where the led should be. I have opt 10 installed.

[Vgkid]

Oh no...
powered it on today,noticed that the display stopped updating, reboot not reading my input. Checked the input on my scope, then ran the self test error 7.0. hooked the timebase out to the scope, i see a nice 10Mhz signal.
Crap.

[PE1RKI]

service manuals: 
http://www.ko4bb.com/manuals/index.php?dir=HP_Agilent/HP_5335_Universal_Counter/HP_5335A_Operating_and_Service_Manual_%28hi-res%29

[orin]

Oh no...
powered it on today,noticed that the display stopped updating, reboot not reading my input. Checked the input on my scope, then ran the self test error 7.0. hooked the timebase out to the scope, i see a nice 10Mhz signal.
Crap.

Check your relay socket.  The first symptom is having the instrument start to act goofy.  See my previous posts on the subject.

[Vgkid]

^^^ Will do, as it passed 7.0, and failed at 7.3 today.
how do you remove the metal clip holding in the relay, mine doesnt want to budge.

[Vgkid]

So I reseated the relay, and lost all front panel functionality,rocked it, and everything worked. All test passed.
Also found out that option 40 is installed(wondered why there so many relays on the A2 board, when there should only be 1.), wish it was the prescaler though.

[orin]

So I reseated the relay, and lost all front panel functionality,rocked it, and everything worked. All test passed.
Also found out that option 40 is installed(wondered why there so many relays on the A2 board, when there should only be 1.), wish it was the prescaler though.

Similar to what mine did - fan came on, but no display.  I disturbed the relay and it started working.

It's time for a new relay socket... part #27E213, PB806-ND from Digi-Key; Mouser and onlinecomponents.com have them too for $2 or so.  Easy enough to replace with a decent desoldering tool.

The bad socket contacts should be obvious, so you could try bending them back a little but it's just a matter of time before they fatigue again and open up.

I'd consider trolling ebay for a 'dead'* unit with the prescaler if you really want the third channel, but it's probably cheaper to get one of the chinese 2.7GHz counters, open it up and disconnect the timebase output...

*fan comes on, no display would be a good bet!

[Vgkid]

Already ordered the socket, I think I would rather just buy/make a /10 prescaler.

[Vgkid]

I was trying to dig up any information in the A/B rear input. I have 2 BNC to sma cables installed. The 2 sma connector portions are just held in plave by a spring metal cable clip not connected to anything. The manual doesn't mention anything, and none of the addendums do either.

[Vgkid]

Necro bump
the "parts" counter came today where is the A4U1b to A4U2b jumper located, that is used for option 10.
Both units appear the same.
EDIT
found the jumper resisyor, was looking for a marked link.

[jmsc_02]

Dear,

Recently I won a 5335a from ebay. I've tested inputs A & B and seems ok.

It's a unit from 1982, I know it by the date of the IC's because the serial prefix has been deleted for someone in the past
Also, the unit has 4 sticks saying "Option 010, 020, 030 & 040". Looking outside & inside I see the OXCO & the cards for the  Voltmeter & Input C but I can not see the 040 opt. I need to study the manual to discover it because I do not find anything commented on this thread.

 a pictures of the unit & I have a question:

Who is lying, the 33210A or the 5335A? (there is a continuous offset of 1,2ppm on frequency measurements)

[Vgkid]

Option 40 is installed. Notice how many more triggering/input buttons are installed compared to the non opt 40 units

[agronaught]

I've enjoyed having my 8335. 

One question though, when the inevitable tantalum failures happen, are you replacing with axial tantaliums or other?

Ive not managed to find a suitable source for these components. 


Sent from my Nexus 5 using Tapatalk

[Vgkid]

I dont think that the axial tants are of the wet slug variety, so you can replce them with uprated radial ones.

[Vgkid]

Does anyone have the size of the back power input connector, or are they almost universal for a given style. I nitifed that my frequency jumps have started appearing again.

[DimitriP]

"Almost universal" would  almost be the correct description. You might have to take it apaaaht before you decide which one from the 1500+ available to order from Digikey

[Vgkid]

I figured that much. Now to place another order, and take it apart again.

[jmsc_02]

Option 40 is installed. Notice how many more triggering/input buttons are installed compared to the non opt 40 units

Thank you! I noticed that seeing the manual, but gave no importance...   

[timb]

Basically, with OPT40, the trigger levels are set with DACs, instead of directly from the pots. (The pots are still there, only the MCU reads them and makes changes via the DACs.)

This allows you to remotely set the trigger level via GPIB. It also adds the "Auto Trigger" button, which automatically establishes the correct trigger levels. Another advantage is the ability to vary the trigger level between the peak-peak voltage of the waveform with the knobs. (Normally the knobs would set the trigger level between -5V and 5V, but with this feature on, if you had say a 2Vpp signal centered at 1V, the knobs would move the trigger between 0V and 2V.)

It's the most useful of all the options, IMO. The DVM is the least useful.

By the way, if anyone has the parts for the C Channel option they want to get rid, I'm interested. I need the boards and front panel insert/wiring. (I could also provide a blank insert to replace it if it's being stripped out of a working system.)

I'd like to retrofit my unit with this option, but haven't had much luck finding the parts.

[sdwest]

Hello all,

I recently upgraded my HP 5335A (S/N 2044Axxxxx) from the standard internal crystal to the 18011-60111 OCXO (Option 010).  My unit came equipped with the standard oscillator crystal, but with a card edge connector for the OCXO already built into the A4 board. The two mounting holes for this assembly were pre-drilled in the board.  The correct service manual for this serial number is 05335-90021, which states that the correct OCXO for this SN is 18011A.  Mine was a 18011-60111, so that's the one I installed. 

Jumper W1 on circuit board A4 must first be removed in order to enable the OCXO operation.  This jumper looks like a 1/8 W resistor, but the parts list shows it as a 22 gauge wire jumper.  I carefully cut and lifted one end of this jumper. 

The 10 MHz crystal should then be removed in order to avoid any possible interaction with the new OCXO.  This crystal is in a TO-5 case (HC-35/U Mil) and has 3 leads, just like a TO-5 transistor.  After much probing around in there, I discovered that the crystal was NOT soldered in, it is merely pushed into a special socket on the cirduit board.  From the top of the board, I was able to work it up and out of the socket quite easily.  I was able to get the part number for this crystal from the parts list in my manual, and did a Google search.  I located another piece of equipment that uses this same crystal, and this manual listed several manufacturer sources for it.  The Bliley Crystal website had the specifications for it, the BK3-1B-10MHz, and I am attaching a .pdf of those specs for anyone interested. (Note: the socket for this crystal is easily mistaken for a triangular grouping of solder blobs.  A closer look reveals tiny holes in the center of each blob, to accommodate the crystal leads.)

I first installed the older 10544A OCXO which also worked just fine in my counter, but since I also had the more stable, newer 18011-60111, I settled on that one.

I want to thank Dr. Frank (this Forum) for his kind assistance in this project.  I wish to also thank EEV contributor max_torque for the photos contained in his post of May 23, 2014 regarding the HP5335A.  I took the liberty of re-using crops from two of these photos of board A4 to help illustrate this project.  I hope you don't mind.

Best wishes to all,

Wade
NW IL

[Vgkid]

Good luck with your 5335. I will be bringing my old one back online in a few weeks. Everything not t&m related seemed to die.

[Cubdriver]

LOVE the opening photo - nicely done!     Unfortunately, it's way past my bedtime, I'm over tired, and I can't resist being a smartarse

<Cue Crocodile Dundee voice> That's not a classic counter. 

 

^^THAT'S^^ a classic counter! <End C. Dundee voice>



(This of course will likely prompt someone to post a picture of their 521C - I haven't managed to get my paws on one of those yet.     )

-Pat

[1980s_john]

Hi,

Summary
I previously worked on my 5335A back in March 2015 (on the input board 'A3 Amplifier Buffer assembly (05335-60003)', I replaced the big blue tant caps (22uF) with new 35V parts), the unit then switched on but -15V and 5.2V volts were missing.

Replace the -15V regulator by a 7915, the -5 volts is depended on the -15V.
because of the op-amp that is in line with the -5 V.

This month I finally pulled it off the shelf and replaced the 7915 (U7 on A1 PSU), and removed the 110V fan and used the spare relay contact to parallel up the 5V relay. Once reassembled it all powers up fine and displays '0' on power up, so I now need to run some tests and learn how to use it!

Detail
I tested the PSU by making up a test lead with a power switch and connected it to J1, and connected up a dummy load of switchable 100/68/47/33 ohm 10W resistors. I found that sometimes the -15V would come up from power on, and sometimes not. When 25 ohm load (ie 0.6A @ 15V) was attached it would never power up.

I found I had to remove most of the boards to access the A1 power supply board, and only when I unscrewed this did I realise the transformer and Q1 wires could simply be unplugged from pins in the board.

A small piece of metal dropped out (see attached) - it seems to work fine without it, but any ideas where it fits?

Thanks for the recommendation to follow the service note to change the fan from 110V to 24V. I unsoldered the two black 110V fan wires and two white wires leading to the mains input module (line input). This left the A1 board free of all wires so much easier to work on. The white wires could then be unplugged from the mains input module, I put some heat shrink over the exposed terminals for peace of mind.

I added jumpers to parallel up the 5V feed, and attached a pair of wires across diode CR7 ready to connect to a 24V fan which is now fitted. The relay and socket don't look damaged (the black marks wiped off) so I left these.

Finally I replaced the 7915 regulator. After checking I refitted the A1 PSU board and it came up fine, the -15V output could drive 25 ohm @ 0.6A, and the -5.2V supply was fine with a 33 ohm load. I checked voltages for +15V, -15V, +10V, +5V and -5.2V and all were good. (Somehow I forgot to check 3V.)

I re-connected the boards one by one and all above voltages stayed fine. My unit has option 010 (HP 10544A OCXO), 020 DVM and 030 C channel (old type).

On power up it initially displays HPIB address, then displays 0. I have yet to try out any of the functions with a signal or even try the DVM, but it is looking good at long last.

Regards,
John

[edpalmer42]

That piece of metal looks like it could be from one of the buttons.  Check here http://www.rbarrios.com/projects/HPSWITCH/ for details.  See if one (or more) of them has no spring return.

Ed

[Dr. Frank]

Yeah, that looks like a metal bar spring out of one of the switches.
Maybe, one of them is 'hanging', when pressed.

Anyhow, these switches always have problems, due to relaxed springs.

Frank

[1980s_john]

That piece of metal looks like it could be from one of the buttons.  .. See if one (or more) of them has no spring return.

Thanks, yes the Gate Mode Normal/Fast has no spring return. Many buttons are clicky too.

Regards,
John

[1980s_john]

Hi,

I plugged my 5335A back-to-back with a lower spec HP counter in our lab, and the counter and timebase out parts both worked fine. I need to tweak the crystal trimmer one day against a GPS based oscillator, the specs for the HP OCXO are way beyond anything else in out lab.

I tried the diagnosis self test and it gave FAIL 7.3, so some issues to sort out, so I am looking for some advice please.

I have a copy of the service and operations manual (scanned by KN5U - thanks!), but I am rather stuck.   As I wrote earlier:

I checked voltages for +15V, -15V, +10V, +5V and -5.2V and all were good. (Somehow I forgot to check 3V.)

Referring to table 8-7 on page 8-59 voltages as per my not good DVM are all within spec:
+15V = + 15.70V
-15V = -15.10V
+10V = +10.02V (fairly sure it is within spec +/- 0.01V - need a better meter!)
+5V = +5.07V
+3V = +3.01V
+24.5V = +25.9V

However, elsewhere in this copy of the service manual someone has crossed out 15.7V and hand written 15.0V as the required voltage, and note to refer to a service bulletin. What gives please? Is this only for 5335A with certain serial numbers?

I tried to follow the service manual on from section 8-241  Troubleshooting (failure analysis), not sure what to make of the results or what tests to run next.

The one that failed was 8-293 Diagnostic #14: Front End Test. With a cable from TBO to Input A, running the diagnostic gives FAIL 7.3. The manual says 'd. Presence of signal in Channel B (FAIL 7.3 if no trigger through COM A).' So I assume the problem is in the trigger circuitry. I guess without a working trigger the 5335A is limited to working as a basic frequency counter.

I'm not sure whether the following results are a pass or fail. These are section 8-310 Diagnostic #26, #27 and #28, trigger level DVM reference test.

#26 gives a result that varies every second between -4 999 68 to -5 000 17, manual says should be -5.0000V. Is it normal to vary by +/-1mV?

#27 cycles between roughly -200 E-6 to 200 E-6, ie +/- 200uV. Manual just says GND REF.

#28 cycles between 4 999 70 and 5 001 00, manual says +5.0000V.

I do not understand section 8-312 Diagnostic #9 and #30, trigger levels A and B test. When run I see numbers between -800 E-6 to 300 E-6. Manual says 'the actual trigger level voltage for both Channels A and B can be varied over the entire range during this exercise' - I have no idea how to do this.

From the troubleshooting flowchart on page 8-57 FAIL 7.3 means a fault in the A3 amplifier assembly. Doesn't look like an easy circuit to work on so I am a bit wary of making things worse.

I am trying to fix this 5335A before returning it to a colleague, but mainly I am just trying to learn new stuff.

I hope someone here can give me some advice or pointers on which section of the manual to go to next.

Regards,
John

[orin]

I seem to remember getting 7.3 errors on my 5335A when it was acting goofy due to a bad relay socket.

I'd pull the relay and take a careful look at the contacts in the socket.  More than the 5V contacts may have fatigued and spread due to heat cycling.  Then I'd put a scope on the power rails and make sure they are clean.  Only when sure of the power supplies after the relay would I try to chase down an error.

[Vgkid]

Those relay sockets cause lots of grief, and different errors.

[1980s_john]

I seem to remember getting 7.3 errors on my 5335A when it was acting goofy due to a bad relay socket.
I'd pull the relay and take a careful look at the contacts in the socket.  ... Only when sure of the power supplies after the relay would I try to chase down an error.

Thanks, I'll recheck the relay socket and scope the power rails. I see Mouser UK has sockets in stock.

Regards,
John

[1980s_john]

Hi,
I've checked the voltage rails with a scope and didn't see any major problems (50mV of noise relative to chassis).

I think I've found a problem with the B channel trigger, please can someone with a fully working 5335A try the following simple test as a comparison.

Set all buttons out, rotate A and B trigger level knobs fully counter-clockwise (past click point), remove all cables.

Power on - check A and B LEDs. I see A LED lit and B LED unlit. Display shows 0.

Press 'Trig Level' button - shows A trigger level voltage on left and B on right.

I get:
0   -4.80

When I rotate trigger A level knob, left digit changes from 0 to -5.19, then increases through 0 to 5.20.

When I rotate trigger B level knob, right digit changes from -4.83 to -0.60.

I assume trigger B voltages should look the same as trigger A 

Regards,
John

[woodchips]

I have just scrapped some 5328 counters, all of which had the option 10 hi-stab oscillator. No idea if they will fit anything else.

[Vgkid]

I have just scrapped some 5328 counters, all of which had the option 10 hi-stab oscillator. No idea if they will fit anything else.

As new as the 5328 is, it should use the 10811 series oscillator. It is used in much hp gear.

[1980s_john]

When I rotate trigger A level knob, left digit changes from 0 to -5.19, then increases through 0 to 5.20.

When I rotate trigger B level knob, right digit changes from -4.83 to -0.60.

I assume trigger B voltages should look the same as trigger A 

Hi,
With help from the Yahoo HP/Agilent group I found the problem was with A2 Amp Support U10, a MUX08 8-to-1 analogue mux that wasn't switching correctly. This provides the trigger level voltage into the B channel on the A3 input board. Once replaced the unit now passes self test with no errors (FE Pass), so I can now tidy it up and try and fix things like the relay socket and dodgy front panel switch.

Thanks for help & advice,
Regards,
John
PS - earlier changes were 4 tantalum caps on A3, 7915 on A1, rewiring relay to double up 5V contacts / change fan from 110V to 24V

[1980s_john]

I strongly recommend replacing the relay socket and implementing the wiring change in the service note or one day, you'll turn it on, the fan will run, but you will get no display.  The relay socket is part #27E213, PB806-ND from Digi-Key. 

Hi,
I ordered a 27E213 socket and it worked well as a replacement. However when I removed the old one from my 5335A the original socket was a 27E129. The only difference in specs is that the 27E129 has a grounding strip and the 27E213 doesn't, but for this application either is fine.

Regards,
John

[1980s_john]

That piece of metal looks like it could be from one of the buttons.  .. See if one (or more) of them has no spring return.

Thanks, yes the Gate Mode Normal/Fast has no spring return. Many buttons are clicky too.

I finally took the front panel off today to fix the buttons. I found it impossible to remove the keycaps from the switches, I tried pulling them straight up but didn't want to pull too hard and break the switch. I fixed the metal strip back into the Gate Mode switch and it worked fine. I checked the other switches and found three where the metal strip had come out at one end and was held by the neighbouring switch. I fixed two of them but on the third the strip snapped in two whilst I was trying to refit it (not easy!). I took the pieces out and reassembled the unit, luckily the switch works fine without the spring - it is the Range Hold switch and pressing it toggles the setting nicely.

All done now, thanks for the  helpful tips and offers of parts,
Regards,
John

[Mrt12]

If you have the DC fan, it's likely that the contacts on the relay socket have opened up.  See the service note in my post above.  The relay socket is a 27E213, Digikey part number PB806-ND.  If it is the relay socket and you do the modification in the service note, you probably don't need a new relay; I'm still using my original relay.  Anyone with a 5335A should make sure that this modification is done and switch to a DC fan.  The 5V supply relay socket contacts get hot, fatigue and eventually, when they cool down, don't make contact with the relay any more.

Thanks, my relay seems to be OK. However removing it shows a black heat mark on the socket, presumably where the 5V passes through. Thanks for the service note, I must give it a go.

The HP part for the relay is 0490-1172. Printed on the side is the code R10A-E1-X6-V430, and a date code 7923. ebay shows loads of R10-E1-X6-V430, is the R10 2A relay and the R10A 5A then?

Regards,
John

Hi guys,
I have the exact same problem! it is very weird - the input voltage to the voltage regulators seems OK, butno output. Somebody mentioned that the relay socket is actually the problem when this symptom occurs. Can someone explain this in more detail?
With the missing -15V, I got Fail 5.1 on my counter, which means 'Interpolator failure', but I don't really believe that the interpolators are damaged - I think they simply don't work if some of the supply rails are missing....

(just in case an interpolator is blown: is there a spare?)

[1980s_john]

Hi Mrt12, please read all the replies on this thread. Regarding the fan change and relay socket, see the service note (https://www.eevblog.com/forum/testgear/hp-5335a-timer-counter-anything-i-should-know/?action=dlattach;attach=128567). I found it useful to print off the circuit diagram for the relay / fan circuit, mark off the changes on paper first then do for real. I can find my paper copy and scan it if wanted. The circuit change is quite simple and results in the high current PSU output feeding through 2 relay switches in parallel thus reducing the current through the socket contacts. As the old relay socket is likely to be heat damaged a new one with good contacts is recommended.

The PSU output voltages need to be correct before worrying about anything else, I had some shorted tantalum capacitors and a failed -15V regulator (7915). I have a spare relay socket available for price of postage.

Regards,
John

[lowimpedance]

Found two service notes (23 and 24) for the 5335a counter at work and this thread seems to be the most appropriate place to archive them.

[rob.manderson]

Found two service notes (23 and 24) for the 5335a counter at work and this thread seems to be the most appropriate place to archive them.

Ah ha! Service note 23.  I found this exact effect on mine.  Since I have no need for rear panel inputs I simply removed them.

[tkamiya]

I must have a later motherboard than manual was based.  Would someone please confirm cream colored "thing" with one black band in middle is the jumper I'm supposed to remove when installing an oven oscillator? 

My Oven Osc says 10811 osc series 3010
What is series 3010?

I think this one came out of HP8568 spectrum analyzer.

[Dr. Frank]

I must have a later motherboard than manual was based.  Would someone please confirm cream colored "thing" with one black band in middle is the jumper I'm supposed to remove when installing an oven oscillator? 

My Oven Osc says 10811 osc series 3010
What is series 3010?

I think this one came out of HP8568 spectrum analyzer.

Hello,
it's too dangerous to agree, based on your description (although I think I know what you mean).

Please have a look in either version of the manual, on page 2-4 it's described, that you need to remove jumper P/N 8159-0005, that is zero Ohm resistor W1, on board A4, so it's designated as A4W1 in the BOM. You'll also find that part in the schematics, and also on the board drawing, please just look one page ahead in this thread, reply #74, where 'sdwest' nicely described that modification.

All versions of the counter are identical around the XTAL circuit.

Your OCXO should probably be labelled 10811-60111; you'll find further info by google search on '10811 osc series 3010'
That type should work in the 5335A.

PS: I had a quick look on my spare OCXO, and yes, 3010 might be the manufacturing date, decoded to CW10 of 1990, if its serial number is something like 3010A01234
 The P/N anyhow, should be something like 10811-60xxx

Frank

[tkamiya]

3010 is a mysterious designator.  On mine, there are two stickers and one says "upgraded to series 3010".  60*** is no where to be seen.  On web entries, there are mostly questions without answers.  I'm thinking it's a some kind of performance version of the whatever unit.

As to the jumper, on my photo, it's little higher than center left.  There are many photos on this board with one trimmer cap version but not two like mine.  I am unable to find a manual that matches mine.

I might install one and route it to Aux input.  That way, I can avoid modifying anything at all.

[Dr. Frank]

3010 is a mysterious designator.  On mine, there are two stickers and one says "upgraded to series 3010".  60*** is no where to be seen.  On web entries, there are mostly questions without answers.  I'm thinking it's a some kind of performance version of the whatever unit.

As to the jumper, on my photo, it's little higher than center left.  There are many photos on this board with one trimmer cap version but not two like mine.  I am unable to find a manual that matches mine.

I might install one and route it to Aux input.  That way, I can avoid modifying anything at all.

Maybe you post a picture of your unit, of the face plate, and of the connector.

All manuals which I know and possess (5335A-90005, 5335A-90021, and 5335A-90044) match exactly your PCB area, and W1 is also clearly visible.

The drawing on the previous page in this thread (#74) also clearly indicates what has to be done, and that matches exactly your PCB, maybe apart from additional C53 cap trimmer, which is visible in manual -90044 . 



Frank

PS: here are the -90044 schematic and PCB drawing:

[tkamiya]

Dr. Frank?  That's not what I am asking....  I was asking about the jumper to remove.  I posted a photo around that area with what I believe to be a fairly clear description.  You'll see that part is slightly different.

Can you help me with that?

You said W1 is CLEARLY visible.  I think so too.  When I asked for confirmation, you told me to be careful and refereed me to a manual.  That's when I got concerned.

[Dr. Frank]

Dr. Frank?  That's not what I am asking....  I was asking about the jumper to remove.  I posted a photo around that area with what I believe to be a fairly clear description.  You'll see that part is slightly different.

Can you help me with that?

You said W1 is CLEARLY visible.  I think so too.  When I asked for confirmation, you told me to be careful and refereed me to a manual.  That's when I got concerned.

Instead of a description, you better would mark the part in question in your picture, then I could safely say "yes".
I simply found your description dangerous to answer, especially such a term like 'cream colored "thing" ' .

I hope, you can now identify W1 on your own, safely.

And the OCXO should simply resemble the pictures of any 10811-60xxx on the net..

[tkamiya]

Done.

I removed what I thought to be a W1.  While there is no indication on the module, some online resources refer to my unit as the right one.  So I installed it.  Power on!  It seem to be working.  Dr. Frank, thanks for putting up with me. 

Is there any indication on front panel to oven is cold? 

Now, the only thing left to do is to replace this noisy fan.

[Dr. Frank]

Was a bit laborious, with both of us, but I'm happy that everything works, in the end. 

In the 5335A manuals, there is no mention of such an indicator, and I don't remember that it has one.
Sorry, can't test that, as my OCXO is still running.

PS: pin 11 of the 10811 is the oven monitor, but is N.C. inside the 5335A. Therefore, definitely no indication possible.

It should run 48h before making any calibration.

And a picture of the faceplate would be nice, for my collection.


THX - Frank

[tkamiya]

I'll have to replace a fan before closing the case.  Then, I'll take the vanity shots.  Thanks for your help.

[tkamiya]

I have a HP5335A just upgraded with HP10811 oven oscillator.  I have GPSDO going to a scope channel 1 and HP5335A clock output going into channel 2.  Trigger is set on 1.  20 ns / div.

What's reasonable expectations?  So far, I have not been able to completely stop the trace movement.  The "slug" is extremely touchy and has some hysteresis.  (move slug, remove tuning stick, it goes back a little)

[Dr. Frank]

I have a HP5335A just upgraded with HP10811 oven oscillator.  I have GPSDO going to a scope channel 1 and HP5335A clock output going into channel 2.  Trigger is set on 1.  20 ns / div.

What's reasonable expectations?  So far, I have not been able to completely stop the trace movement.  The "slug" is extremely touchy and has some hysteresis.  (move slug, remove tuning stick, it goes back a little)

I don't know how long GPSDO machine and OCXO are already running.

Anyhow, you can easily trim the OCXO to < 10^-9, i.e. to exactly 10.000 000 00x MHz.
Below, the resolution of the trimmer is too bad.
The metal screw driver you're using also influences the result.

I would apply the 10MHz, or the 1pps from the GPSDO to the A input and simply measure FREQ or PER with longest possible Gate Time, that's about 5sec.

That will give enough resolution to trim to that mentioned limit. I also have described an easy modification of a capacitor to get > 10sec Gate Time, and 10 digits resolution.

The OCXO will usually be stable to around 1^-9 over a longer period of time.

Oh yes, the GPSDO signal itself is quite unstable on these short time scales. 1E-9 at 1sec might be achievable, otherwise use TimeLab and GPIB for better trimming over longer time scale.

Frank

[tkamiya]

I should stop here then.  I have 10.000,000,00x MHz

My GPDSO has been running for over a month, perhaps few months.  I have a redundant setup and results are the same using either or.  I'm at a point where mere pressure will change the result. 

[tkamiya]

This is my 5335A on internal OCXO displaying rubidium source.

A little concerning that OCXO, when measured via 12 digit counter has an upward trend.  It has been on for 24 hours already. 

[0culus]

Upward trend? I guess that's not the picture.

[tkamiya]

No, the picture is a "beauty shot"....

I'm not sure what it is, but when monitoring internal clock frequency using GPSDO trained 12 digit counter, I see a very slow upward trend on clock frequency.  It's VERY SLOW.  But nevertheless, it should not be happening.  I'm going to let it run for 24 more hours and see if it continues.

[tkamiya]

I wonder if my oven module is damaged....  I expected outside metal to be warm to hot.  It's not even luke warm.  It's same temperature as other components....  The upward trend is still continuing.

[0culus]

I wonder if my oven module is damaged....  I expected outside metal to be warm to hot.  It's not even luke warm.  It's same temperature as other components....  The upward trend is still continuing.

Yeah, that's not right at all. All of the ones I have (5335A, 2x 8568B RF sections, 3325B function gen) all are quite warm to the touch when the oven has had wall power for a while.

[tkamiya]

That's what I thought.  Most of them gets hot enough that it's uncomfortable to touch for long.  Darn!

Now it explains why it's behaving oddly.  Tomorrow, I'll check 24V first, then start looking.

[0culus]

Here's a little experiment I did that might give you a datapoint. The 3325B has been unplugged for a couple of days, so I plugged it in and started monitoring a 10 kHz 0 dBm sine with the 5335A (which has been on power for about a week now). Took about 1.5-2 hours but the 3325B oven settled out reasonably well after pretty considerable swings when it was first turned on. I believe it may take quite a bit longer than that to truly settle, but at the same time, once the oven gets to temp it should stabilize a lot.

[Dr. Frank]

The 10811 has to get warm, otherwise the oven is not working. Strange, that you can trim to zero anyhow.

So, what is the rate, anyhow, and how / what do you measure in practise?
The 10811 is stable only after 48h, as I wrote already, and will be stable then to about 1E-9, maybe more, if it has been off for a longer time.

To check the oven, you may apply 24V to the oven circuit externally, that should consume 500mA on power on, going down to around 2..4W after 15 min, or so..
If not, the internal thermal fuse may be defect, what often happens on vintage 10811.
It can be replaced by a short w/o problem.

Frank

[tkamiya]

It's odd.  I tested the oscillator by itself.  It did consume 0.42A and declined.  It got slightly warm.

Cleaned contact and reinstalled.  Now it's QUITE warm.  So it might have been a case of oxidation.  I didn't do anything at all.  I'll have to keep an eye on it.  It *may* have some intermittent problems.

[Dr. Frank]

 all contacts are gold plated, so that's not that probable.
This thermo fuse might have a problem, as well as the oven regulator circuit.
I once repaired a 10811 inside a 5370B, which has an oven indicator. So I could quickly find out, that its NTC intermittently failing to open, which gives no heating.
Was a mechanical / vibrational error also.

[tkamiya]

Oxidation may be a wrong word.  More like contamination.  I had plenty of times gold plated sockets and connectors failed me.

I believe I'm having an intermittent issue.  One time, it's quite warm to touch.  Another time ambient.

[tkamiya]

I have some data now.

The frequency drift appears to be a result of cooling by fan.  To reach this conclusion, I stuck a thermocouple on side of OCXO and charted time, temperature, and frequency.

With case top open, it measured 34C and last two digit of frequency was 98.  (last digit is 10^9)
With case top open, 30 minutes later, the temp went up to 41C and kept going.  At that time, frequency was 94.
Now, close the case temp start to goes down.  14 minutes later, back at 34C and frequency was 98.

So temperature co-effecient is somewhere near 1 x 10^9 / C
Rate of drift is 1 x 10^9 / C (obviously...)
This should stabilize at some point.  Tricky part is adjustment.  It may take few hours once case is opened and closed.
Once it reaches equilibrium, I expect drift to be less.

Looks like HP has designed a very efficient duct system.  I looked at the temp fuse.  It's socket-ed.  So I cleaned both and reinserted.  I think this is working.  Perhaps when we tune, we leave the case open, so we have impression that OCXO runs that hot all the time?  I don't think this is over-cooling because some chips run quite hot and they are closer to the fan.

Opinions, please.

[Dr. Frank]

The 10811As specified T.C. is < 2.5x10^-9 over an environmental temperature range of 0..71°C. (see page 1-2 in manual of 10811A).
So your observations might give too high a T.C., but maybe  can not be distinguished so well from other influences.
Also, the specification is given as a 'box method', not directly as ppm/°C.
Maybe the oven control is not ok. A monitoring of the oven power consumption over temperature may give more hints.

Its timely drift is specified < 5x10^-10 /day. So your observations are inside specification.,

I suppose, that you let the counter plugged in all the time, so that the 10811A is continuously powered.
When I switch my 5335A on, I also observe a slight drift of <1x10^-9 after a few hours of internal heating up.
I use the counter in a room at 21°C +/- 2°C over the whole year.

The timely drift of my 5335A is less than 1x10^-9 over a year, meanwhile the 10811A is so old, that it has settled.
Again, whenever I unplug the 5335A, it takes > 48h to reach the old value within < 2X10^-9.

I recommend to let the 5335A warm up for several hours, with the lid unscrewed, but closed.
By briefly shifting the lid open, trim the 10811A as close as possible to 1x10^-9 deviation and observe again with closed lid, and repeat adjustment 1-2 times.

I think, my counter meanwhile displays about 2x10^-9 deviation, several years after last adjustment.
That's totally fine, because that is really at the limit of what is possible with an OCXO.
You need a Rb reference to get even lower deviation, about 1/100 of that ballpark.

Frank

[Dr. Frank]

Ok, I fired up my 5335A @ 9:39h. Room temperature was about 21.1°C, Gate Time 12.5sec for 1x10^-10 resolution.
Reference is the Trimble Thunderbolt, with the "good" Trimble OCXO inside. Samples vary 1 digit only, i.e. by +/- 1x10^-10.

  9:39 => 9.999 999 970 MHz
10:34 => 9.999 999 969 MHz
11:24 => 9.999 999 967 MHz

So the warm-up or retrace effect (oscillator was off before) is <= 3x10^-10
I opened the lid, and attached a thermocouple thermometer on top of the case of the 10811.

12:00 => 9.999 999 970 MHz @ 31.6°C, just opened lid
12:45 => 9.999 999 970 MHz @ 38.0°C, open
13:00 => just closed lid, 32.0°C
13:17 => 9.999 999 969 MHz @ 29.4°C, closed
14:17 => 9.999 999 969 MHz @ 29.3°C, closed

So, the change over temperature is about/less than 1x10^-10 over a 9°C change.

Your OCXO seems to be too sensitive against temperature changes, although it might still be in spec. of the 5335A manual, page 1-4, i.e. <7x10^-9, 0 to 50°C.

My 5335A drifted by about -2.2x10^-9 over at least 2 years, maybe longer, see Reply #27 here in this thread. OCXO was continuously running since that time.

Frank

[tkamiya]

I guess you have a particularly good OCXO.  I know mine sat idle for years before I started playing with it.  I'm going to keep it plugged in for a while and repeat the test. 

Maybe all it needs is a cup of morning coffee.

In few days, I will have another 5335A, this time with factory option 10.  So I will be able to perform a direct comparison.

I actually have many rubidium modules.  The problem is power consumption.  It takes 2.5A total per spec, 1.8A actual measurement.  I actually tried to fit that all in.  I couldn't find a good placement for the power supply to be not near input and not near Rb.  So I am going with an external solution.

[Dr. Frank]

Maybe, but in my memory, the other (repaired) 10811 inside the 5370B performs similar.

I also switch off my FRS-C Rb standard, due to high power consumption.. as it's mandatory to mount them on a big heat sink / metal plate.
Several Rbs inside one case, with one common heat sink might be a problem.

I packed 2 power supplies, 1 Rb, and the GPSDO inside a slim 19" case.. everything fine so far, only the Rb affects the Trimble stability a little bit.

Frank

[tkamiya]

I might have exponent expression wrong.  My measurement was : 10,000,000,00x where x changes.  That's 10^-9? or 10^-10?  Input is 10MHz.  I always mess this up!

The GPS I have is PRS-10 and FRS-C.  I intend to use former and slave it to GPS.  To avoid any interactions, power supply will be linear and external.  So it'll be shielded from temp change and magnetic field.   

I am revamping my house standard.

I was also surprised how much Rb drifts.  It took good 24 hours to completely stabilize.

[Dr. Frank]

I might have exponent expression wrong.  My measurement was : 10,000,000,00x where x changes.  That's 10^-9? or 10^-10?  Input is 10MHz.  I always mess this up!

The GPS I have is PRS-10 and FRS-C.  I intend to use former and slave it to GPS.  To avoid any interactions, power supply will be linear and external.  So it'll be shielded from temp change and magnetic field.   

I am revamping my house standard.

I was also surprised how much Rb drifts.  It took good 24 hours to completely stabilize.

That change would be x * 10^-10.
The un-modified 5335A has 4s max. Gate Time, so only 10^-9 will be displayed/resolved.
So maybe you should have a 2nd look, what you really measured.

My FRS-C needs about one week, until it has stabilized to parts in 10^-11.. that drift-time always depends on the limit criterion used.
I have provided an external potentiometer to adjust the Rb to 2*10^-12, but drifts are on the order of 1*10^-11.

[tkamiya]

Ah, thank you. 

I have naked rubidium oscillators as well as cased ones from Efratom.  On one version, adjustment hole wasn't available as it was completely covered with heatsink (without an access hole!)  So I did the same thing.  Glued a multi-turn pot to inside and punched a small access hole on top cabinet.  Just for a good measure, put a sticker on it.

I need to do your modification to my 5335... 

[0culus]

I might have exponent expression wrong.  My measurement was : 10,000,000,00x where x changes.  That's 10^-9? or 10^-10?  Input is 10MHz.  I always mess this up!

The GPS I have is PRS-10 and FRS-C.  I intend to use former and slave it to GPS.  To avoid any interactions, power supply will be linear and external.  So it'll be shielded from temp change and magnetic field.   

I am revamping my house standard.

I was also surprised how much Rb drifts.  It took good 24 hours to completely stabilize.

That change would be x * 10^-10.
The un-modified 5335A has 4s max. Gate Time, so only 10^-9 will be displayed/resolved.
So maybe you should have a 2nd look, what you really measured.

My FRS-C needs about one week, until it has stabilized to parts in 10^-11.. that drift-time always depends on the limit criterion used.
I have provided an external potentiometer to adjust the Rb to 2*10^-12, but drifts are on the order of 1*10^-11.

You can open the gate manually to get the full digit capability. I think there might be a way to control that over HP-IB?

[Dr. Frank]

Yeah, both ways work.

It was a pleasure for me to discuss and measure, as I learnt a lot new about the  behaviour of the 10811.

PS.. and my 5335A now got a genuine Cal Sticker, as it's now freshly adjusted to 3*10^-10

[tkamiya]

You had me confused for half a day....

The reason I have 10 digit number is because my setup is as follows.

DUT is HP5335A with 10811.  It's clock out is connected to ANOTHER COUNTER
This ANOTHER COUNTER gets its clock from redundant GPSDO OXCO and/or Rb

So I am just treating HP5335A as an oscillator. 

I've also done the other way around as well.  But I gain an extra digit doing it the way I described it.  Also it's newer and faster. 

I've never ever looked into behavior of oscillator this much, and witness its drift.  Case open/close thing was an eye opener.  Surprising how sensitive it is!  So, Dr. Frank, are you satisfied with performance of my 10811 now that we know it's actually 10^-10, not -9?  Should I pursue this further?  Like I said earlier, in a week or so, I'll have another HP5335A.  It will be fun to compare responses side-by-side.  Also in planning stage is Rb with GPS.  I'll have to do something with ambient temperature changes.  My lab is the hottest room in the house.  I'll have to make a small compartment and insulate it to see what it will do.

Thank you very much for your instructions.  It helped great deal.

[Dr. Frank]

You had me confused for half a day....

The reason I have 10 digit number is because my setup is as follows.

DUT is HP5335A with 10811.  It's clock out is connected to ANOTHER COUNTER
This ANOTHER COUNTER gets its clock from redundant GPSDO OXCO and/or Rb

So I am just treating HP5335A as an oscillator. 

I've also done the other way around as well.  But I gain an extra digit doing it the way I described it.  Also it's newer and faster. 

I've never ever looked into behavior of oscillator this much, and witness its drift.  Case open/close thing was an eye opener.  Surprising how sensitive it is!  So, Dr. Frank, are you satisfied with performance of my 10811 now that we know it's actually 10^-10, not -9?  Should I pursue this further?  Like I said earlier, in a week or so, I'll have another HP5335A.  It will be fun to compare responses side-by-side.  Also in planning stage is Rb with GPS.  I'll have to do something with ambient temperature changes.  My lab is the hottest room in the house.  I'll have to make a small compartment and insulate it to see what it will do.

Thank you very much for your instructions.  It helped great deal.

Sorry, that I confused you, I was not aware of that. 

Anyhow, your 10811 is definitely working fine, as thermal drift is down in the 10^-10 ballpark. At that resolution it was more or less a go/nogo test of the oven, what we have discussed so far, and a bit beyond, very interesting also for me!

If you want to dig deeper into the performance, you'll have to use different techniques and evaluations.. It's then all about 'Stability'.
So you might compare the 10811 against the GPSDO or Rb, using Allan Deviation (ADEV) statistics. This gives you the relative stability figures on different timescales.
"Relative" is important, because on short time scales, most free running OCXO are superior over GPSDO, and even Rb, due to the high jitter of the GPSDO signal, and of the noisy Rb signal. See ADEV diagrams from different time-nuts, how the different standards perform, relative to MASER or Cs standards.

http://www.leapsecond.com/museum/manyadev.gif
http://www.leapsecond.com/pages/adev-avg/

The residual x*10^-10 variance might also arise from GPSDO instability, instead from the 10811 itself, if you were using effective Gate time of 1sec, or less, only.

You may instead use time interval methods, on 1pps signals derived from these standards, and a resolution of 1ns for T.I. (like the 5335A) is already  sufficient for that.

Do you have a Fluke /  Philipps counter, or an agilent 53131/132A, or even a KS 53220/230A? These feature better interpolation techniques, like 100ps, or down to even 20ps single shot, like the very old HP5370B, or the SR620.. That would improve / speed up the ADEV measurement.

Oh yes, again, TimeLab from kfe5x is highly recommended for that. There you'll find also several ADEV graphs for various standards.
http://www.ke5fx.com/timelab/readme.htm

Looking forward to your next 5335A, and picture of this mysterious 10811 3010 series.
Frank

[tkamiya]

I have HP53131A hooked into GPSDO. 

Problem with Allen deviation is I really don't understand it and I lack facility to actually measure that kind of precise and repetitive measurement.  I've purchased GPIB interface, so I might try it at some point in time.  For this experiment, I used HP53131A in frequency A mode and used long gate time.

Here's a picture of 3010.  Other than these two mysterious stickers, they are identical to everyday 10811-6011.  It came out of parted out HP8568A upgraded to B.  Right now, these are available for like 60 dollars so I may buy a few and keep them in my stock. 

I wish I can make use of my Rubidium stuff but just their size and heatsink requirement, and power is stopping me.  It works with switcher but it is really recommended to use a linear supply.  I had 3 of them running concurrently and it definitely made the room much warmer, so that's a problem, too.

I think I'm becoming a time-nuts....  I'm already a test equipment anonymous.

[FriedLogic]

Plotting ADEV and similar is only part of the analysis. They are designed to look at random noise processes, but there are a lot of systematic processes also going on. These may show up on an ADEV plot, but it's not usually the best way to investigate them.

Oscillators can be sensitive to temperature, pressure, humidity, magnetic fields, etc., and the best way to check for this is usually to keep a log of them to add to plots of the frequency and phase. These can be processed in various ways by averaging, removing drift, measuring correlation, etc. to understand the behaviour of the oscillator in different situations, and so give the best chance of optimising its performance. The effects can also be delayed, which further complicates things.

Although ADEV is often quoted for short times like 1-100s, it's valid over any time period, so you can still get some use from it even it you don't have a very fast and high resolution counter.

One slight complication with the 53131A/53132A/53181A is that their frequency modes do not do a single 'Gate Time' measurement, but rather do what is effectively a lot of overlapping 'Gate Time'/2 measurements. This adds some filtering, and also a triangular weighting to measurement, and the ADEV of measurements done with them will be low compared with the actual ADEV. It is still useful for comparing with measurements done on the same or similar counters.

[tkamiya]

OCXO is good at short term.  Not so at long term.
Rb is good at long term.  Not so at short term.
Cs is great but not so with my budget.
Hm is super great but not even a possibility at home.

I am going to experiment with GPS trained Rb trained OCXO.  That's the best I can do.

I wonder how do we even know Cs is wrong when it IS the standard....

[Dr. Frank]

OCXO is good at short term.  Not so at long term.
Rb is good at long term.  Not so at short term.
Cs is great but not so with my budget.
Hm is super great but not even a possibility at home.

I am going to experiment with GPS trained Rb trained OCXO.  That's the best I can do.

I wonder how do we even know Cs is wrong when it IS the standard....

Cs, like Rb has a small dependency on magnetic fields, so you have to cancel these externally.
This dependency is much, much smaller than Rb.

The primary clocks were all compared against each other, and that median will define the UTC.

Comparison is done by bi-directional satellite links, or by GPS.

PS: You already have all tools on hand to make stability studies, and to analyse the collected data on any wanted way, ADEV, MADEM, freq. deviation.. all inside TimeLab, which also has a complete data collection routine for these commonly used counters.

GPIB access, and a few BNC cables, and you're done. One of your standards has 1pps for sure, so that would be a good starting point.

It's much easier to do, than you think!

[tkamiya]

What I really need is a GOOD understanding of time device management.  That inter-dependency of nature (Cs vs Rb vs XO) of medium (short term vs long vs very long) also needs to be clear.  I'm going to have to get the setup ready and follow along existing resources such as TimeLab.  Since there does not seem to be one "best method", I'm thinking there won't be one device that does all. 

Maybe I'll make two identical setup and do a controlled comparison study.  I have a stack of Rubidium modules.  It should be quite interesting. 

[tkamiya]

A new HP5335A with OCXO and 1.3GHz option just arrived.  It is in beautiful shape and seems to work as it should.  I will be keeping it plugged in for a day or two and see where it settles.

My goal is to have two of each so I can do A/B testing easier. 

[FriedLogic]

Maybe I'll make two identical setup and do a controlled comparison study.  I have a stack of Rubidium modules.  It should be quite interesting.

That's the way to go. Once you have a basic test rig set up you can build on that, then decide what performance you want to aim for and how to measure it. Once you get it up and running you'll get a better idea of where to go next.

If you're trying to squeeze the best performance from a rubidium, temperature is normally the most important thing, followed a fair bit after by air pressure - but that's more a discussion for one of your rubidium threads rather than this one.

[tkamiya]

Dr. Frank,

As I mentioned earlier, I acquired another HP5335A and this time, it comes with factory oven crystal, 10811-6011.  After overnight warm up with case closed, I opened it this morning and immediately touched top and side of the module. 

They are only very very slightly warm in certain spots.  Other parts are absolutely same temp as air around it.  This unit still has a factory fan.  (a turbo jet!)

So it is confirmed that IS the expected behavior.  HP has designed a duct system that keeps the Xtal cool.  I am not going to keep the case open to validate how hot it will get.  I think it's unnecessary.

I thought I'd report in and leave this, in case someone else wonders in future.

[tkamiya]

Fried Logic....  what an interesting handle!

To do an A/B comparison, I'd like to keep everything else the same except the element I'm testing.  I know each counter has certain characteristics since they are so heavily software involved.  I've learned they do quite a bit of massaging and post processing before the data gets on display panel. 

Besides....  this unit was very inexpensive on eBay.  I couldn't refuse....

[LazyJack]

Yes sorry, I'm a bit late.
I had to study all the change history in manual 05335-90044, up to Serial Prefix 3154.

V1.1 had been introduced in June 1984, for all instrument with 2424A06001 and above.

V1.1  has one decimal point in the HP-IB string, as shown with my instrument.
V1.0 shows no decimal point in the GP IB string at all.

I already have the newer prescaler  in the C-channel (05335-60034), which divides by 64.
The old prescaler (05335-60009) divided by 20 only, therefore the firmware has to match.

It's not clear, if there exists an intermediate firmware which corrects all the bugs of V1.0, but is made for the old prescaler, i.e. multiplies the result by 20 instead of 64.

The difference may be inside the EPROM A4U22, as 05335-80012 (as in my unit) refers to the new /64  prescaler, and 05335-80006 refers to the old /20 prescaler.
That's change 7 in this manual, and affects prefix 2820, exactly my counter, and also for retrofitting the newer C-channel option 030.


Obviously, I have an intermediate A4 version, 2 EPROMs - but V1.1 and the newer prescaler. Perhaps my instrument had been updated, or the C - Input had been replaced.

I could not find a comprehensive table, which EPROM code refers to which firmware version, and/or to which prescaler.
Frank

Sorry to resurrect this thread, but I found this table. It is in the latest service manual (05335-90444, recently uploaded to KO4BB). It's on top of page 6-9 .

[mindcrime]

Hey guys, I was just looking at buying an HP5335A that comes with options 010 and 040, but not 030. I'm tempted, but am wondering - if I were to buy it, how hard would it be to find the parts (and anything else needed) for the option 030? The device is probably worth the money even without it, but that would be a really nice addition...

Or would I be better off holding out for a 53131A or similar, for which there seem to be plenty of option 030 cards (including clones) that are readily available?

[LazyJack]

You can sometimes get the opt030 kit on ebay. It is a board plus the front panel. But be careful. There are two versions of it, one with a divide by 20 and the other is a divide by 64 prescaler. The later is for newer models, with v1.1 firmware.
I have one 5335a with all options. A good instrument, but quite large and somewhat loud.

[mindcrime]

You can sometimes get the opt030 kit on ebay. It is a board plus the front panel. But be careful. There are two versions of it, one with a divide by 20 and the other is a divide by 64 prescaler. The later is for newer models, with v1.1 firmware.
I have one 5335a with all options. A good instrument, but quite large and somewhat loud.

Yeah, now that you mention it, the size factor is probably the biggest reason I didn't already pull the trigger on buying the beast. I'm kinda out of room for test equipment anyway, especially something that big. I think I'll hold off for now.

[OH2LIY]

Hi, I did build this opt.30 using what I could find my bonk storage. I works nicely


73 Ramppa

[LazyJack]

Very nice! Thanks for sharing the design.

[TERRA Operative]

So my turn to get one of these up and running again... 
I picked one up from Yahoo Auctions with options 010, 030 and 040 fitted. So far it seems to work ok, pending the usual relay/fan fix and whatnot.

I also need to replace the red 7-seg display cover as someone in the past must have used the wrong cleaner which caused it to warp severely and fog up badly. If anyone has a spare one of these (plus a few of the little black clip thingos), I'll be happy to buy it from you.

My question at the moment though, is my unit seems to have some extra blanked-off positions on the rear panel that don't seem to exist in any of the manuals I've found online.
I assume the 4 in the center are for moving the front panel connections to the rear, but does anyone know what the ones I circled in red are for? Maybe for rear panel connections to option 020?

[LazyJack]

Yes, they are the rear panel options for the Voltmeter option. These options apparently were only available on later units, as older ones do not have the cutouts for the rear connectors.
I think the rear connections are option C10. They are connected in parallel with the front connector, so they will decrease the bandwidth, there is a service note about it.

[David Aurora]

(Necroposting just to possibly keep useful 5335A info in one place)

I just picked up one of these last week from a forum member, thought to be working but it's a bit iffy on first tests. Just trying to work out whether these are normal quirks or if I should make some time to dive in properly and do some repairs.

First up is the startup condition- manual says it should boot straight into counting frequency on input A. I *think* I've seen it do that once maybe, but generally it doesn't. I get nothing until I manually press both COM A and auto trigger, then it works fine. Is that normal?

The other thing is rise/fall/slew modes. Period, duty etc all seem to measure and display fine, but I get nothing from rise/fall or slew modes. I shoved in the example signal in the manual (I think it was something like 400nS rise/fall, 10µS period, 1VPP, it's not in front of me right now), set it up as described and nada. Tried playing with all sorts of settings and I still got nothing. If I check trigger level it shows the 10/90% trigger points, so obviously it's measuring/calculating something at least, but for whatever reason it doesn't display the rise/fall/slew rates on the display. Am I missing something about using these modes?

[David Aurora]

(Necroposting just to possibly keep useful 5335A info in one place)

I just picked up one of these last week from a forum member, thought to be working but it's a bit iffy on first tests. Just trying to work out whether these are normal quirks or if I should make some time to dive in properly and do some repairs.

First up is the startup condition- manual says it should boot straight into counting frequency on input A. I *think* I've seen it do that once maybe, but generally it doesn't. I get nothing until I manually press both COM A and auto trigger, then it works fine. Is that normal?

The other thing is rise/fall/slew modes. Period, duty etc all seem to measure and display fine, but I get nothing from rise/fall or slew modes. I shoved in the example signal in the manual (I think it was something like 400nS rise/fall, 10µS period, 1VPP, it's not in front of me right now), set it up as described and nada. Tried playing with all sorts of settings and I still got nothing. If I check trigger level it shows the 10/90% trigger points, so obviously it's measuring/calculating something at least, but for whatever reason it doesn't display the rise/fall/slew rates on the display. Am I missing something about using these modes?

Scratch that, just popped it open and things started making sense. Channels were cross patched, not sure why but I'm guessing because of a fault, other bodges present too. Looks like I've got work to do

[TERRA Operative]

Have fun, and be sure to do the relay/relay socket/12V fan mod for reliable operation.

Also, there is an electrolytic cap on the PSU section, just next to the small green edge connector that I have found is really needing replacement in 2 out of 2 units I've poked at so far.

[Dr. Frank]

Some pictures of the hacks, of the PCB, options, versions and the general condition of the instrument would be nice, anyhow.

THX
Frank

[David Aurora]

Yeah, I'll do a proper look check of caps etc at some point soon, safe to say given the age it will need some love like that. Fan wiring looks shocking, so I'll assume that was someones crack at the mod. Rear relay section looks clean from the top, though I did pull it and clean pins as a quick check for other issues.

Option wise it has everything except the DVM. General condition is good, but yeah- definitely has some front end issues that have been swept under the rug and shoehorned into basic operation.

I did a little troubleshooting late last night and the signal never makes it out of A12 alive on channel A. Signal is present on channel B at the output of Q4 and off to the next board, but dead on Q12. Coax had been crossed from A12 channel A to A11 channel B and vice versa, so I guess they were running it around the damaged input channel and that's why I had to hit those settings as well as why those measurements like slew didn't work.

Jumping back I found the signal was already dead at the output of U4, EXCEPT if I set the trigger control to minimum (just clicked out of preset). In that state the waveforms match between channels, but as I raise it the signal disappears. Trigger adjustment control itself works fine and ATL signal appears correct. I stopped there, I'll try to get in a bit further on my lunch break if I get a chance, but that definitely gives me some suspicions to check.

[TERRA Operative]

Another thing to check as a matter of course, especially on abused units is the 50ohm termination resistors, they can end up burnt out if care wasn't taken.

I have an entire spare working unit not to be parted out (sans display window.. why do people use harsh chemicals to clean these???) but I'm not sure if I have accumulated any spare PCB's yet.. If I come across any in my piles of gear, I'll let you know. The input chips are the special ones and can be hard to find.

[David Aurora]

Another thing to check as a matter of course, especially on abused units is the 50ohm termination resistors, they can end up burnt out if care wasn't taken.

I have an entire spare working unit not to be parted out (sans display window.. why do people use harsh chemicals to clean these???) but I'm not sure if I have accumulated any spare PCB's yet.. If I come across any in my piles of gear, I'll let you know. The input chips are the special ones and can be hard to find.

Thanks!

I'm thinking if I hit a wall on ICs I may steal from the B channel to get a fully functional A channel as a temporary solution so I can at least test the main functions properly.

[David Aurora]

Confirmed, U5 is cooked. Good thing I haggled when I bought this, I was told it was working properly but went in assuming it was a crapshoot.

And so the chip hunt begins!

[David Aurora]

Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work.

Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work?

[Dr. Frank]

Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work.

Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work?

Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval.

[David Aurora]

Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work.

Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work?

Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval.

Thanks for confirming! Back to the naughty shelf it goes until I find another IC

[Dr. Frank]

Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work.

Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work?

Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval.

Thanks for confirming! Back to the naughty shelf it goes until I find another IC

Better search for a front end replacement, as this IC might be unobtainium.
This double channel electronics was identical to another HP 500MHz counter, I just don't remember the model No. This other, elder counter was quite cheap to acquire.

[David Aurora]

Just swapped U2 and U5, unit now counts as it should on channel A (and obviously now not on channel B). So that's some progress I guess, I don't have to press a bunch of buttons at power up to make it work.

Still no action on rise/fall and slew modes though. I can't be stuffed digging in any more today to figure out why. Given that those modes enable COM A mode though, I'm guessing there's some kind of internal routing that uses both channels for these modes and with one dead channel it doesn't work?

Correct, those modes require both working channels, because you need two distinct trigger levels between you measure the Time Interval.

Thanks for confirming! Back to the naughty shelf it goes until I find another IC

Better search for a front end replacement, as this IC might be unobtainium.
This double channel electronics was identical to another HP 500MHz counter, I just don't remember the model No. This other, elder counter was quite cheap to acquire.

Yeah, I'll keep an eye out for whatever I can get to button this thing back up I guess. IC's, whole boards, junked units, other units with the same part, whatever pops up first and gets it working again 

Frustratingly I didn't even really want it but grabbed it because I'm always loaning gear to people and thought another counter couldn't hurt. But I think by the time I sort this out I'll have pumped far more effort into it than it was worth 

[TERRA Operative]

I had a look through my spare PCB's. Unfortunately while I have the two 'motherboards' I don't have the input board.

I'll keep an eye out locally if one pops up though.

[David Aurora]

I had a look through my spare PCB's. Unfortunately while I have the two 'motherboards' I don't have the input board.

I'll keep an eye out locally if one pops up though.

Thanks!

I asked on an HP group as well, and I'm watching eBay. With any luck something will turn up somewhere

[Wrenches of Death]

Also, there is an electrolytic cap on the PSU section, just next to the small green edge connector that I have found is really needing replacement in 2 out of 2 units I've poked at so far.

All of mine are buttoned up and stacked right now.

Is this the small upright radial leaded Sprague capacitor designated as A1C2?

The manual lists it as 100uf @ 15VDC. If so, I'll drop a few in my Mouser cart and snag them on the next order.

Were yours leaking, bulging, or failing electrically?

Many thanks in advance!

WoD

[TERRA Operative]

Yeah, that's the one. Mine tested almost no capacitance so I think they dried out or something.

I just replaced them with a 105degree rated cap. I think one of my two units even got the exact original type capacitor )possibly higher voltage though) as they are still available new, but it's not a critical application here I think so any decent capacitor would be fine.

[Wrenches of Death]

Yeah, that's the one. Mine tested almost no capacitance so I think they dried out or something.

Thanks. I just added them to my cart and pulled the trigger. All three counters seem to be behaving other than one of the little transistor sized relays for option 40. The easiest way to check it was to simply remove the driver transisor. The relay is bad and tough as hell to find new for a reasonable price. I've got a parts hulk around here that I'll eventually get around to robbing a used relay from.

If I don't forget, I plan to test the three original A1C2 caps after I replace them and will post the results. With both of yours being bad, this may be a common failure component and well worth replacing in any 5335A.

Thanks again!
WoD

[Wrenches of Death]

Yeah, that's the one. Mine tested almost no capacitance so I think they dried out or something.

I received the Mouser order this morning and just finished replacing the A1C2 caps in three 5335A's, and removing and testing one from my parts hulk.

I installed 105C 180uf @ 25V caps.

I tested the old ones that I removed and found the following:

All were Sprague 672D 100uf @ 15V rated at 105C

A1C2 from SN 2152A024xx tested @ ~ 50pf with a date code of 8121H
A1C2 from SN 2424A061xx tested @ ~620pf with a date code of 8337H
A1C2 from SN 2448A066xx tested @ ~110pf with a date code of 8426H1
A1C2 from SN 2820A120xx tested @ ~143pf with a date code of 8812H

With the two that you tested and found bad, I think I'd go out on a limb here and state  that it would be a safe bet to automatically replace A1C2 in any 5335A that crossed your path.

Thanks for your post that brought these to my attention!

I just pulled A1C2 from my parts hulk and added it to the above list. It's even worse than the other three.

WoD

[TERRA Operative]

Yep, I agree. Mine tested about the same capacitance too.

[Wrenches of Death]

Yep, I agree. Mine tested about the same capacitance too.

I had to place another parts order and went ahead and added a couple of pair of replacements for the 2000uf A1C12 and A1C13. I pulled the originals on the 2424A prefix counter this morning and they both measured 2100+uf with good D and ESR. I put them both back in for now.

While I had it apart, I pulled the 17,000uf A1C14 and tested it. It was in the high 15,000uf range. D and ESR were acceptable. I then pulled the smaller 8000uf A1C16 and it tested in the mid 7000uf range.

Both of these were within the -10% tolerance for those two cap positions, but I can foresee possibly having to replace them somewhere down the line. To be honest, I trust 40 year old US made high end Sprague caps more than the vast majority of the stuff that's out there on the market today.

Did you test any of these four caps in your counters?

WoD

[TERRA Operative]

I took a chance and didn't bother with the big ones. From my experience, the big caps generally tend to last without much trouble.

I probably should throw them on the 4276A LCZ meter to check them.... I'll add it to the 'to-do' list.... A rather long list that is.