Tektronix 5000 series (1970-1990 era) shenanigans

[TerraHertz]

Interesting thread. I too like rackmount scopes, and I have a few - mostly R7903s.
I do have three 5103N (D12 and two D13), and had spotted that they could be converted to rackmount. But alas I'm unlikely to find time to do it.

[WastelandTek]

Those look great TerraHertz!  Really clean.

You called it David; ground side foil corroded in half



Oh man, this thing smells GREAT inside /sarc, so this is where that "old electronics" smell comes from, ugh.

Some illumination on nomenclature; upon reviewing the physical 5444 manual it turns out that is what I have.  5443 refers to the acquisition frame and a 5443 mated to a D44 display is a 5444.  This is pretty cool as the 5444 is sort of the holy grail of the 5000 series, being 2 scopes in one tube a-la the 7844, and makes me VERY hopeful that the tube itself is not damaged.  They were only offered in the 1976 catalog and are pretty uncommon.

The dave_k capacitor boards have arrived from OSH Park and look quite good so it is time for me to be ordering electrolytics.  For years I have been pretty liberal in my capacitor replacement choices, figuring that if some is good more must be better, and I have had pretty good luck with that.  Reading around here, however has given me pause as I see some are claiming that excessive voltage derating does not enhance reliability as the caps will quickly "reform" to the lower voltage and that higher voltage rated parts will have higher ESR to no benefit.  While these arguments do make sense to me I am torn as I have become comfortable "overdoing" it in both capacitance and voltage rating.

Here is the relevant schematic with the caps in question pointed out



here are the specs per Tek

C800 170uF 275V       (between +30 and +200V rails)
C848 10,000uF 12V    (+5 - GND)
C875 7,500uF 25V      (+20 - GND)
C876 7,500uF 25V      (-20 - GND)
C930 5,000uF 50V      (+38 - GND)
C932 3,000/5,000uF 50V  (-38 -GND)

C932 is 5K in the 5444 and 3K in the 5440 (and all the other 5xxx) supplies

here is what is in my Mouser cart awaiting your critique

C800 220uF 315V ELXS3B1VSN221MP3
C848 18,000uF 16V EKMH160N183MQ40T
C875/6 10,000uF 35V EKMH350VNN103MR
C930/2 6,800uF 50V EKMH500VNN682MA3

Am I crazy?  Is this too much?

[tautech]

IMO

C800 220uF 315V ELXS3B1VSN221MP3

Should be OK.

C848 18,000uF 16V EKMH160N183MQ40T

You need consider that you could potentially double the inrush current through the bridge at power on.....not advisable.

C875/6 10,000uF 35V EKMH350VNN103MR

Similar but not as bad as above.

C930/2 6,800uF 50V EKMH500VNN682MA3

Again, pushing things to a point that may cause problems.

Am I crazy?  Is this too much?

Not crazy, just get a handle on the consequences of selection far from what the design stipulates and the reasons why.
There is every chance it won't matter damn all but are you willing to take the risk ?
Not me. 

[WastelandTek]

Yeah, I get it that the inrush through the bridge diodes is the limiting factor.  I have always sort of assumed that the values chosen back in the day were heavily influenced by size and cost, which are not really issues any more.  The bridges look pretty beefy, and diodes are not exactly unobtanium...are there any OTHER reasons not to go hog wild with main filter caps?

Also, can I add a current limiting resistor to soften the power on blow to the bridge?

[tautech]

Yeah, I get it that the inrush through the bridge diodes is the limiting factor.  I have always sort of assumed that the values chosen back in the day were heavily influenced by size and cost, which are not really issues any more.  The bridges look pretty beefy, and diodes are not exactly unobtanium...are there any OTHER reasons not to go hog wild with main filter caps?

Also, can I add a current limiting resistor to soften the power on blow to the bridge?

NTC thermistors are often used to manage inrush current but another thing to consider is the ESR of the replacement caps. Lower ESR and higher capacitance will both contribute to higher inrush currents.

[WastelandTek]

OK, please don't think I did not really want your advise, how about this cart?

C800 220uF 315V UPS2F221MRD
C848 15,000uF 16V UVZ1C153MRD
C875/6 10,000uF 35V UVZ1V103MRD
C930/2 6,800uF 50V UVZ1H682MRD

all Nichicon 105C parts

[tautech]

OK, please don't think I did not really want your advise, how about this cart?

C800 220uF 315V UPS2F221MRD
C848 15,000uF 16V UVZ1C153MRD
C875/6 10,000uF 35V UVZ1V103MRD
C930/2 6,800uF 50V UVZ1H682MRD

all Nichicon 105C parts

Closer. 

There's still some room for you to be more conservative. 

I know if it was mine I'd be sticking close to the same values back, sure it's a hassle just to have to replace them but why add the risk of more hassle ?
Your call. I won't think bad of you whatever you decide. 

[WastelandTek]

We'll let it sit a while and hopefully accrete some more opinions.  I freely admit I tend to being an all or nothing sort of guy.  If it was up to me I'd probably build the Dyson capacitor, using all conductive material in the solar system for the plates and the rest for the dilectric....death to ripple.

[David Hess]

Oh man, this thing smells GREAT inside /sarc, so this is where that "old electronics" smell comes from, ugh.

Ethylene glycol is or was a common solvent in aluminum electrolytic capacitors and is a common element of "old electronics" smell.  I think propylene glycol was used in aluminum electrolytic capacitors rated for lower temperature operation.

Some illumination on nomenclature; upon reviewing the physical 5444 manual it turns out that is what I have.  5443 refers to the acquisition frame and a 5443 mated to a D44 display is a 5444.  This is pretty cool as the 5444 is sort of the holy grail of the 5000 series, being 2 scopes in one tube a-la the 7844, and makes me VERY hopeful that the tube itself is not damaged.  They were only offered in the 1976 catalog and are pretty uncommon.

I forgot about this.  The 5000 mainframes were also used to make other instruments like curve tracers so the top and bottom frames have different part numbers.  Tektronix also OEMed them for others to make instruments out of.

For years I have been pretty liberal in my capacitor replacement choices, figuring that if some is good more must be better, and I have had pretty good luck with that.  Reading around here, however has given me pause as I see some are claiming that excessive voltage derating does not enhance reliability as the caps will quickly "reform" to the lower voltage and that higher voltage rated parts will have higher ESR to no benefit.  While these arguments do make sense to me I am torn as I have become comfortable "overdoing" it in both capacitance and voltage rating.

Higher voltage capacitors are physically larger and have more electrolyte so they have a higher ripple current rating and take longer to dry out.  However there is a change in electrolyte above about 160 volts which yields a higher ESR but up to that point, higher voltage is always better.

C800 170uF 275V       (between +30 and +200V rails)
C848 10,000uF 12V    (+5 - GND)
C875 7,500uF 25V      (+20 - GND)
C876 7,500uF 25V      (-20 - GND)
C930 5,000uF 50V      (+38 - GND)
C932 3,000/5,000uF 50V  (-38 -GND)

C932 is 5K in the 5444 and 3K in the 5440 (and all the other 5xxx) supplies

here is what is in my Mouser cart awaiting your critique

C800 220uF 315V ELXS3B1VSN221MP3
C848 18,000uF 16V EKMH160N183MQ40T
C875/6 10,000uF 35V EKMH350VNN103MR
C930/2 6,800uF 50V EKMH500VNN682MA3

Doubling the value of C848 may be a little much.  Just use the closest or next higher standard size for replacements so 220, 10000, 8200 or 10000, 4700 or 5600, 3300, etc.  The risk if an input capacitor is too large is from excessive surge current although saturation in the transformer will limit this somewhat.

If an input capacitor fails with a short, then its associated input rectifier should be replaced.  Some Tektronix instruments had rectifier upgrades do to poor reliability.

[WastelandTek]

Well, I owe you folks an update.

Excess disposable income has been a little thin of late, and I have not been able to justify actually purchasing my parts shopping cart, which has grown rather large with parts for multiple outstanding projects.  I have, therefore, sidestepped into a related project, related enough, I think, that it fits in this thread.

Meet the Pacific Measurements (later gobbled up by Wavetek, later gobbled up by Wandel & Goltermann, later gobbled up by Fluke) 1038 system, in this case configured as a dual port network analyzer. 



It used the Tektronix D1x displays and a very similar 3 bay mainframe system to the 5K Tek line. I became addicted to the dual port network analyzer some years ago when I had a buddy that worked at a VERY swank lab and we could go in the night and use the equipment.  Once you have used one, doing any real RF work without seems like stumbling around in a dark cave with a book of paper matches as opposed to exploring with a nice big torch.  In the pic above, the system is displaying the S₁₁ and S₂₁ of a typical RF low pass filter simultaneously.  You can tweak on the DUT and observe the effects in real time.  This is VERY handy for developing an intuitive sense for circuit behavior.  Once you have used one it is really frustrating to go back to doing it any other way.

Unfortunately, another feature of such systems is that they tend to be pretty expensive, at least modern ones.  I was lucky and was able to assemble all the requisite bits over a couple years' worth of swapmeets at less-than-eye-bleeding prices.  Most of the expense of putting something like this together is actually in the autotester bridge and detectors.  These PM/Wavetek display frames have become quite affordable.

This one is in the process of being converted from the side-by-side rackmount configuration to over-under so I can use the rackmount mechanical parts to convert a nicer, late production, 1038-D14A.



I'm not sure I really recommend disassembling them this far, but this one was disgusting inside.  It had a really thick coating of that black, high voltage, soot all over in the display unit.



The deflection amps in these D10s seem to run pretty hot.  I'm going to see about getting some more airflow up here.



One of the deflection leads was threatening to short to chassis because the heat had baked the insulation off.

[Electro Detective]

Great post mate 
please reserve a ringside seat for me too    

I've got 2 of these I restored last century, 5111s I think,
one is fully loaded with two 4 channel plugins and delaying time base (killa scope),
and also a dead/donor/project rackmount version,

all still in storage (no pun intended) due to a premises move

Will have to get to them and fire up carefully asap 

[WastelandTek]

Welcome to the thread ED, thanks for stopping by.

4 channel plugins

ahh yes, the 5A14N.  I don't have one yet, they are one of the coolest plugins for sure.  Surprisingly, they come by on ebay quite frequently and are one of the cheaper plugins to get.  There are two cleanish looking examples right now for less than $40 each (not shipped-US) which I have to say is pretty dammed painful to resist.

[Electro Detective]

If they were in this part of the woods, I'd hit on them and fill up another box,
more than good enough for LF and audio work,

and that monster crt screen rocks   

You can't have too many channels.. or scopes..

or w....   

[WastelandTek]

Well guys, I have run into a snag.

Got the donor 1038-D10 all reassembled in the vertical configuration and when I applied power the HV protection neon bulbs, DS271-3, lit up and R273 started smoking.

I shut it down pretty quick and R273 still reads in spec.  The thing was working before disassembly, so it is definitely something I did.

I'm going to have a careful, patient, poke around it and have a good think.  Here are the relevant schematic and circuit description.  If anyone wants to chime in it would be much appreciated.

[WastelandTek]

oh man...

http://www.ebay.com/itm/Tektronix-5111-Storage-Oscilloscope-/122313864004?epid=1201603091&hash=item1c7a797344:g:VIMAAOSw2xRYfWfr

[Electro Detective]

oh man...

http://www.ebay.com/itm/Tektronix-5111-Storage-Oscilloscope-/122313864004?epid=1201603091&hash=item1c7a797344:g:VIMAAOSw2xRYfWfr

Delaying the "Buy It Now" thing for 20 bucks with 3 others 'Watching' is some serious risk taking   

Find out what the shipping charges are asap so the parts/donor/maybe working deal doesn't hit $200   

[WastelandTek]

Well, I managed to resist that, they wanted $80 shipping

but this happened

[WastelandTek]

Whelp, I fear that, barring a sourcing miracle, or a sudden leap in DIY engineering, that the 067-0680-00 calibrator is a bust.

The staircase works, which is nice as far as it goes, and the normalizer amp seems to work, so I got that going for me, but the pulse generator is missing the absolute unobtanium 10ma 4.7pF tunnel diode 152-0177-00.  This is one of the notorious custom Esaki devices that can not be had for love nor money, and have been the end of so many Tek scopes.  none of the commonly available soviet NOS tunnels seem to share this parts relatively stout current and very low capacitance. 

Someone had attempted to replace the tunnel diode with a bog standard 1N4152 which...isn't going to work.  In their defense, there is a typo in the 067-0680-00 manual which does, in fact, call out a 1N4152 as CR280.  This is clearly incorrect, but "fortunately" this fixture is nearly identical to the earliest versions of the 7000 series calibrator 067-0587-01, note that the -02 and -03 revisions of the 7000 calibrator are completely different.  The 067-0680-00 schematic indicates a 10mA tunnel, so I am fairly certain that 152-0177-00 is indeed the part.  In this online picture you can just make out the characteristic gold DO-17 case of the device in question.  I can only hope that my missing one was scavenged to fix a much nicer piece of gear.



I had high hopes for the calibrator, they are pretty uncommon.  There was a typo in the ebay listing and the buy it now price was the lowest I have seen, plus I was able to bundle shipping with the other lot of 3 plugins pictured above.

The beauty of the calibration fixture, as I understand it, is that it supplies very fast risetime pulses directly to the mainframe input pins allowing tuning of the square edge compensation adjustments in the vertical amps in the frame.  Without it you must apply pulses through a vertical plugin, in my case an uncalibrated plugin, which multiplies the unknowns and complexity of adjustment.  I am thinking that my fall back position might be saving up for a Leo Bodnar pulser and try and figure out how to couple it direct to the frame through a JAMMA cable, though I'm not sure the impedance is going to match...and the length of the cable...oh never mind, that's not going to work either...

 

maybe a little PCB with the 2 card edge pins, a matching network, and a BNC for Leo's pulser...and get a leprechaun to reach in the frame and hook it up?  I'm pretty sure leprechauns are easier to find than tunnel diodes.

[alm]

Is the pulse transition time that critical for the 5000 series? I believe the fastest mainframe was 50 MHz, and that was a special (5400?) series that had its own dedicated plugins. I can not imagine the skin effect loss from a piece of coax soldered to a header connector would be visible at all. Obviously you would need the correct impedance and might need a differential signal.

[WastelandTek]

Greetings alm, welcome to the thread.

I am working on a 5440 and a 5444 here, so the 50/60 MHz stuff.  It is entirely possible that Tek went a little overboard with the risetime.  Near as I can tell the tunnel should rise on the order of 400pS which, at 875MHz bandwidth, does seem a bit quick for the application.  I kind of suspect that they were binning the diodes from GE and the nicer ones became 152-0177-01 or 152-0177-02 and they had a pile left over that they used here, but who knows.

There are 10mA tunnels available with higher capacitance

1n3719 10ma 27-50pF

1I305A 9.2-10.4 ma  <30pF

1I305B 9.6-10.8 ma  <30pF

I might get a batch of 4 of the Russian ones for $15 and see what happens.

The first stage on the mainframe interface board is indeed a differential pair, 470k to ground.

[David Hess]

The 5000 and 7000 series calibrators all use some variation of a transconductance output circuit for the pulse output with diodes to disconnect the edge from a shunt termination.

The tunnel diode used in the 500 MHz 7000 standardizer and the 50 MHz 5400 standardizer (they both use the same design) is *not* part of the output circuit.  Instead, it sharpens the pulse from the clock generator before it enters the differential amplifier chain.  It could be replaced with any 10 milliamp Ge tunnel diode or with a 10 milliamp GaAs tunnel diode if resistor divider R288/R289 is adjusted to take into account the change in voltage step.

Alternatively, I doubt the 50 MHz standardizer needs that sharp of a pulse at the input of the differential amplifier chain anyway.  The tunnel diode could be replaced with a resistor and a resistor placed across C125 to create the proper amplitude at the base of Q282.

Or even better, I might actually replace the tunnel diode with a small signal schottky diode or 2N3904 base-emitter junction to control the amplitude at the base of Q282, add the resistor across C125, and adjust other resistor values at the input to get the right levels at the collectors of Q310 and Q312.

[WastelandTek]

Well....

Clearly I have come to the right place for help.

1N3719 are $30 for 2 on Ebay right now, if you don't think that an order of magnitude more capacitance is an issue that is probably the easiest solution

[WastelandTek]

So the DO-17 cased 1N3719 tunnels for the calibrator arrived.

I have read dire warnings about the thermal fragility of these Germanium devices.  I don't have any specifically low temp solder here, mainly just 60/40.  I can clamp some heat sink to the body.  What do folks think as far as iron temp; hot and fast or cool and slow?

[dave_k]

Clamp each leg with a hemostat to sink the heat, and go hot 'n' fast.

[WastelandTek]

Well a warm welcome to the thread dave_k!!  Your thread figures large in the inspiration for this project.

If you read above you will see I have your capacitor adapter boards here, thank you so much for the gerbers!