Test Equipment Anonymous (TEA) group therapy thread

[Addicted2AnalogTek]

I've been working on verifying a late model PG506 non-A that I think I've finished repairing, and was pleasantly surprised when I took a look at the fast rise output - I was expecting it to be somewhere around 900pS (based off measurements others have shared).  Setup is PG506 fast rise output, 012-0482-00 "SG503" precision coax, Amphenol BNCF->3.5mm adapter, into 11802 delay line in. Delay line out to SD-22 via rigid coax. 11802 set to AverageN #4096.



The repairs were invasive but minimal: Rebuild the variable amplitude pot, clean cam switches, replace C732 (2uf 150V) due to dry rot on end plug, replace C135 due to it measuring as failing (lead lifted, DER5000 tested), and I replaced the tantalum caps on the fast rise board with higher voltage rated 199D's. I also copied TERRA's move with the hot water modeling "clay" and JB weld to repair my broken amplitude knob, which I'm very pleased with. I used JB weld Plastic Bonder Tan to try to get a close color match, and it's okay, but translucent instead of solid tan.

[factory]

Some info for Med & the 204C thread over on the other TEA place; https://teanonymous.com/f1/viewtopic.php?t=387

I've noticed you are planning to replace all the capacitors in your HP 204C, note that the large axial one on the mainboard is a non-polarized type, it's the 300uF 10V one marked 0180-0140 & VNP (the same part is used in the HP 209A), the parts list in the manual for the 204C doesn't mention anything about this.

P.S. the HP 211A, is the symmetry out on all ranges? I note the lower frequency ranges use those bumble bomb capacitors* and the higher ranges use Mica dominos, these are the capacitors on switch S1 that are still original.

*these are listed as Mylar in the parts list, but might be worth checking them with a Megger, in case they are paper in the older ones.

David

[med6753]

Some info for Med & the 204C thread over on the other TEA place; https://teanonymous.com/f1/viewtopic.php?t=387

I've noticed you are planning to replace all the capacitors in your HP 204C, note that the large axial one on the mainboard is a non-polarized type, it's the 300uF 10V one marked 0180-0140 & VNP (the same part is used in the HP 209A), the parts list in the manual for the 204C doesn't mention anything about this.

P.S. the HP 211A, is the symmetry out on all ranges? I note the lower frequency ranges use those bumble bomb capacitors* and the higher ranges use Mica dominos, these are the capacitors on switch S1 that are still original.

*these are listed as Mylar in the parts list, but might be worth checking them with a Megger, in case they are paper in the older ones.

David

Thanks for the info on the 204C.

211A: The symmetry issue is much worse on the lower frequency ranges but gets better as you go up in frequency. On the highest range it's "almost there" at perhaps 60/40. I too are suspecting the range capacitors, especially those black beauties. But I want to rule out any vacuum tube issues first. I'm also going to pull CR1 and isolate the trigger circuit from the multivibrator.

[TERRA Operative]

I also copied TERRA's move with the hot water modeling "clay" and JB weld to repair my broken amplitude knob, which I'm very pleased with. I used JB weld Plastic Bonder Tan to try to get a close color match, and it's okay, but translucent instead of solid tan.

Pics please! 

[factory]

Some info for Med & the 204C thread over on the other TEA place; https://teanonymous.com/f1/viewtopic.php?t=387

I've noticed you are planning to replace all the capacitors in your HP 204C, note that the large axial one on the mainboard is a non-polarized type, it's the 300uF 10V one marked 0180-0140 & VNP (the same part is used in the HP 209A), the parts list in the manual for the 204C doesn't mention anything about this.

P.S. the HP 211A, is the symmetry out on all ranges? I note the lower frequency ranges use those bumble bomb capacitors* and the higher ranges use Mica dominos, these are the capacitors on switch S1 that are still original.

*these are listed as Mylar in the parts list, but might be worth checking them with a Megger, in case they are paper in the older ones.

David

Thanks for the info on the 204C.

211A: The symmetry issue is much worse on the lower frequency ranges but gets better as you go up in frequency. On the highest range it's "almost there" at perhaps 60/50. I too are suspecting the range capacitors, especially those black beauties. But I want to rule out any vacuum tube issues first. I'm also going to pull CR1 and isolate the trigger circuit from the multivibrator.

https://teanonymous.com/f1/viewtopic.php?t=379

A bit more digging for info on the 211A, the part numbers 0160-0018 & 0160-0022 which are listed as Mylar caps, well the NSN disagrees and states those are fixed paper dielectric, as we both suspect. The ones in mine are the Sprague 160P mixed dielectric, they need to hit the bottom of the nearest bin.

P.S. the two white Goodall type 663 capacitors are plastic film types, these are still made by ASC capacitors;
https://ascapacitor.com/wp-content/uploads/2025/02/663-Data-Sheet.pdf
https://ascapacitor.com/history/

I've no idea if you have an insulation tester or not, but I use the small Megger BM8 for quick identification of unknown type capacitors, to find the leaky paper ones.

David

[Addicted2AnalogTek]

I also copied TERRA's move with the hot water modeling "clay" and JB weld to repair my broken amplitude knob, which I'm very pleased with. I used JB weld Plastic Bonder Tan to try to get a close color match, and it's okay, but translucent instead of solid tan.

Pics please! 

Will do as soon as I can. I also intend to try various other JB weld colors with other knobs that I need to repair.  I unfortunately have my home air handler in pieces right now due to a plugged heat exchanger, so I must tend to that first. Carrier/ICP (manufacturer) problems....

[Addicted2AnalogTek]

Pics please! 

[TERRA Operative]

Nice work!

I actually need one of those knobs too....

Do you mind getting your vernier calipers out and measuring it up for me? I wouldn't mind getting something 3D printed in resin (my knob has nothing left besides the aluminium insert!  )

If you could measure all the major dimensions in mm (height, width at top and bottom, width and depth of internal holes, etc etc) I would really appreciate it!

[TobyG]

And the -042 of the older hardware revision is specced for 10A/20A (boost), only.
Might get a chance to take a closer look at one of those, too, soon.

What can I say.
Look at the thread title and add the fact they sold comparatively cheap, on auction.

Now got one newer revision -016, one newer revision -042 and two older -042.
I don't think I'm gonna need any more of them. Not that I needed four of them, to begin with.



They three -042 all looked like they'd been fished out of a dumpster, bent/scratched panels and one was missing the potentiometer knobs, but the 3D printer made a quick job of that.
The top one has one broken jack, replacement is gonna be in my next electronics order, other than that, only cosmetic damage,
the panels got a tactical beating, et voila, they are straightened out.

[RichardM]

I definitely have an acquisition problem. I saw this Honeywell RF Probe for AU$50 and couldn’t help myself. Thought it would be useful for troubleshooting vintage repairs etc. The probe is air tuned ? For 26MHz to pick up micro arcing due to faulty solder joints or components according to the manual. I guess this means I would need another type of probe for radio signal tracing?

[Addicted2AnalogTek]

If you could measure all the major dimensions in mm (height, width at top and bottom, width and depth of internal holes, etc etc) I would really appreciate it!

I just got an SG502 recently (haven't tested) that'll need a knob if it's not destined for the parts stash. Same boat as you - the aluminum insert exists, but none of the plastic remains. Though the clear part behind the knob does exist.

I've attached a rough sketch and dimensions for the 366-1711-02 knob for Tek PG506 Late / PG506A. I measured off of a fully intact knob, not the previously repaired one. The dimensions don't take into account the insert, or insert depth, as it's just lined up flush with the back of the knob. If that doesn't cover it, let me know if you need any more info.

[rdenney]

Sigh. The next step in my emerging pile of HP slabs is an older HP 339A distortion analyzer. I basically don't care if a piece of audio equipment does better than CD quality (96 dB S/N), which studies have shown is indistinguishable in actual listening from higher S/N ratios. And with amplifiers, I'm happy if they are better than 80 dB SINAD. The 339A should do that well enough. I gather it's about the best analog distortion analyzer that was made, at least that is generally available. Also, it's convenient to use and has an excellent low-distortion oscillator built in and usable for other purposes. If I ever need better than that, I'm going with something computer-based.

The HP 5334b that I mentioned upthread arrived and appears to work perfectly--I am pleased. Dates in the early 90's. I replaced the RIFA caps, which gave me an excuse to take it apart and inspect things carefully. The Type X RIFA caps showed only a small amount of the cracking that leads to their death. It's clean as a whistle inside, and just the usual wear outside. The ONLY tricky part of pulling the PCB out the front to replace those safety caps is finding the right 9/16" wrench to loosen those BNC lock rings that nail them down to the front panel. It has the OCXO and the 1.3 GHz options.

The only remaining bits I might be looking for are 1.) a function generator at audio levels, and 2.) an RF signal generator. I can use the oscillator in the 339A for lots of audio testing, I'm thinking, so the RF generator might be first. I would really like to be able to service FM tuners and also my ham-radio receivers.

Rick "needs a bigger shelf" Denney

[timeandfrequency]

I definitely have an acquisition problem. I saw this Honeywell RF Probe for AU$50 and couldn’t help myself. Thought it would be useful for troubleshooting vintage repairs etc. The probe is air tuned ? For 26MHz to pick up micro arcing due to faulty solder joints or components according to the manual. I guess this means I would need another type of probe for radio signal tracing?

Looking at the schematics : batteries are directely charged by mains. No transformer used as isolation barrier.

For tracing radio signals, check out this DIY E-field probe .
Another build of the same probe.

[RichardM]

Yes. I decided to remove the mains charging cable and just installed some AA batteries. I may make the non contact probe in the link you provided. I assume the existing circuit does not need any further modification for this type of probe? Everything works really well, not far out of calibration as is.

[m k]

So charging 9V and 5V in series?

[tverbeure]

It took blood, sweat and tears, but I got my Rohde & Schwarz AMIQ to the point of sending out a constellation diagram.



Work needed:

* full recapping of the motherboard. All caps were completely shot. Despite knowing better, I powered it up before the recap and the motherboard actually made it all the way to the boot screen. After the recap, I checked the old ones: 1500uF caps measured at something like 25uF. It's a miracle it got this far!
* hard drive failure. Replaced by a compact flash drive. Took ages to find the right recipe to get the right disk image.
* CPU fan broken. I needed quite a bit of force to turn the thing. I wonder how that even happens?
* CR2032 battery empty. Obviously.

I'm still having some issues uploading large waveforms from WinIQSim to the AMIQ: it goes all the way to the end, then it hangs and eventually times out. WinIQSim and GPIB doesn't work on a modern PC.

I did a teardown of the whole machine and a deep dive of a bunch of interesting analog circuits here: https://tomverbeure.github.io/2025/04/26/RS-AMIQ-Teardown-Analog-Deep-Dive.html.

If anyone has a cheap R&S SMIQ for sale... 

[Robert763]

I had similar experience with a AMIQ. capacitor failure is normal for PC mother board of the vintage.
My AMIQ driving the analog I/Q on a R&S generator that does basically all that a SMIQ-03 with I/Q input does but cost a lot less.
It a SFQ TV transmitter test set. They can sometimes be picked up very cheaply.

Robert.

[tverbeure]

My AMIQ driving the analog I/Q on a R&S generator that does basically all that a SMIQ-03 with I/Q input does but cost a lot less.
It a SFQ TV transmitter test set. They can sometimes be picked up very cheaply.

Thanks! I'll check it out! Does it require certain options or will every SFQ do just fine?

[Vince]

Hi people, it's Vintage Tek spring cleaning time !


I have started downsizing my collection of hollow state Tek scopes, so I thought I would mention it in case someone here needs some part they can't find on-line. I have also a couple scopes that I will be trying to sell because they are in excellent shape and it would totally break my heart to take them apart for parts then scrap the metal. 

I already parted out a junk 531A and x4 type 317 scopes, one of which was filled with cement somehow... rough life it must have had...
I still have x3 more 317, two that I will part out today I think, and one that I will try to sell because I restored it 7 years ago and it's in really nice shape. I even went through the trouble of replacing the crusty UHF connectors on the front panel, which is a major undertaking (doubt I will ever do it again, way too much work) but it really makes the scope "pop". I powered it up a few weeks ago, still works, all power rails still good but we have a display issue, trace is shrunk and tilted at bit. Will look into that so that I can sell hopefully a working scope.

I keep only small parts, so the CRT, transformer and cabinet/chassis get scrapped, fan as well. So if you need any of that, be quick...


Other scope in good shape I will be trying to sell, is a show-room condition cute little 310A scope, that comes with its original, bespoke Tek leather carry bag.
According to my notes, I apparently tried to power it up 3 years ago, it tripped the breaker. Primary of the transformer was measured, it was not shorted. So I assume some filter can cap must be shorted and needs replacing. Worst case, the accompanying rectifier tube is shot as well but that's cheap and easy enough to replace. So I will try to get it going before putting it up for sale, so I can hopefully get decent money for it.

That was for the small / portable 3" scopes.

Now as far as the full size 5" scopes go, I intend to part out the following  : one 585A and two 545A.

Don't worry, even once all of that is out the door, I will still be left with a dozen of these old scopes to keep me company, and a dozen more CRT scopes mostly Tek, from more recent vintages, plus a few more scopes from other brands. It's not like I was running out of scopes anytime soon...

[Vince]

Well, you never know what you are gonna find in these old scopes...
Just started parting out another 317 and I found this a minute ago...


Never seen these things before. A guy at some point apparently could not get hold of a 6AN8 tube, so instead he used a 6BL8 which apparently is equivalent electrically but not mechanically : pinout is different but no worries, apparently there exists this thing : a pinout converter ?! 

[PA0PBZ]

a pinout converter ?! 

Nice! Was that home brew or bought, any idea?

[Vince]

The white labels are clearly hand made but the adapter itself is clearly professionally made.
I just had a quick look on ebay, searching for "tube pinout adapter", and found a variety of such adapters, some looking exactly like this one.
So yeah, it's definitely a thing, they are out there...

[m k]

Intuition says that socket saver was a norm, at least sort of, so not far from converter.
Other thing is how usually the needed extra space was available.

[Vince]

Yeahhhh... my restored 317 scope is now fixed, it's back in the game !
Ready for sale then....


Murphy hit me though : the problem looked like a typical vertical amplifier issue, with tired tubes leading to a major vertical offset, and gain issues as well.

So, once I witnessed that, I went ahead and scrapped my last two 317 scopes, thinking I would only need tubes or passives components to fix the scopes.

Well, Murphy decided that no, the vertical amp would be just fine and instead, what failed was the one thing that never ever fails : the freaking DELAY LINE !!! 
WHAT ?!
The 317 is an older scope among the hollow state Tek scopes. These early scopes feature a horrible delay line that massive, gigantic... a super long, L-shape sub-assembly (highlighted in yellow in the picture below), made of a looonnnnnnnng series of individually tuned LC cells, 25 of them or so, no less....
Turns out it was open circuit in the upper beam path. With an ohmmeter I was able to pinpoint which inductance was open circuit. I then shorted it using a test lead, quick and dirty. That fixed the issue, 90% of it. Then I was only left with more moderate offset issue which I was able to quickly eradicate by swapping tubes in two of the four stages of the vertical amp.

So now I need to make the fix permanent by soldering a wire, argh... of course it's bound to have some bad effect on frequency response, but at least I can see it has zero bad effect on the square wave from the calibrator. It's still super square and sharp, lovely. As good as you can humanely get it.

Good enough for sale at the least... and it's not like I was advertising it for 2 grand and pretending it was a brand new scope eh !!! 

I also have lots of period correct accessories for this scope, to make it more attractive / help the sale.. a couple different, original paper manuals, a viewing hood to isolate from ambiant light, and a few period Tek probes.  My little 317 will be the best on the market ! LOL

Hell I might even try to flog it on ebay, internationally to see if I can make more money there than locally on Leboncoin.fr.
I never sell on ebay, but from reading you all here regularly, the impression I get is that rules change all the time, and that handling international sales and taxes, import related shit, is a nightmare, obscure and Russian roulette. Not sure I want to go there, will probably get burned....

If anyone wants it, you have priority (and a discount....) ! 

[Vince]

EDIT : oops forgot. As for the issue the scope had, wit a shrunk and tilted trace.... that was an easy "fix" : turns out the wire for the upper beam deflection plate, at the CRT glass, was disconnected somehow....
You might not believe it but it's amazing how much better a TE performs when you connect all the wires where they should go !