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

[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.