Test Equipment Anonymous (TEA) group therapy thread

[Vince]

Thanks for that !

Same type of TE and same era, also a major brand, so that means my TE was probably trying to solve the same problem.

So that means it's probably not a two stage power ramp up, but an overcurrent protection.

It  starting to make sense now.

I just replaced all the x13 "small" tubes, one at a time. TE never buzzed, and all tubes light up.
But as soon as I plug either or both of the big 6080 tubes, it buzzes.

So that makes sense. These two big tubes means big power hence the ones an overload protection system would want to monitor / protect.

I had a look at the manual for the HP 212A, PSU department. They have a couple 6AS7, similar to the 6080, and their relay seems related to these tubes.

So my relay must be not to switch the full on power, but rather like HP to protect the x2 6080 tubes if they are overloaded, hence why it only buzzes when these tubes are plugged in, and doesn't care about any of the other tubes.

So I guess this means my relay is kaput, as it fails to cut power (either to the tube, or the entire instrument, depending how it's implemented), and rather it's the fuse blowing.
So I need to check that as well once the root cause of the problem is fixed.

So this also means I must have an actual overload issue, since the fuse blows, rather than a "false alarm", the relay being triggered when it should not.

Also... I found out in my Tek tube spreadsheet, that I have a few of those 6080 in some of my scopes. There is one in each of my seven    type 317.
So I picked one... was actually marked 6AS7 not 6080, but well.... tried it anyway, looked the same. Result = it still buzzes.
Then in doubt, I tried pulling the 6080 from my only known good type 317... the one I restored years ago. It's an actual 6080 not an 6AS7, so confidence was higher.
It still buzzes.

So we are making progress !

1) Buzzer and relay most likely an over current protection circuitry
2) Mlost likely protecting whatever those two 6080 tubes are feeding.
3) The two 6080 are not at fault.
4) Buzzer most likely like HP, trigger at the same time as the relay
5) Relay fails to protect the instrument since the fuse blows instead. So eitehr defective, or its circuitry.
6) Relay secondary issue but not the root cause.

So either the rails fed by those 6080s are shorted, or the circuitry driving the grids of those tubes, is faulty and grounds the grids, making them conduct fully.

However it still kinda intriguing that just when it buzzes, and before the fuse blows... all power rails are up, which would mean none are shorted, and still intriguing that all of them read 50% of what they should be...

So maybe we have a third issue, maybe we do have a two stage power up sequence, and it's faulty.

This is repair is not an easy one... zero schematic, 15 tubes just for a PSU... I will keep at it fora few days but I am not too hopeful, looks like more than I can chew 

[Vince]

OK, to answer your question about solid state and rectifiers...

I took note of all tube references, looked them all up, and checked for SS diodes.

Tubes we have :

x2 6080 Dual triode
12AT7 Dual triode
12AX7 Dual triode
x2 6AQ5 Pentode
x4 6AU6 Pentode
x4 QQE03/12 (aka 6360 apparently) dual Tetrode
85A2 (aka OG3) 85Volts regulator tube.

So.... ZERO rectifier tube in there !

SS diodes ? There are 4 circuit boards mounted underneath the deck.
Only one of them carries diodes, 4 of them. However it's more like 2 diodes since they put two of them in series, twice.
They are all of type OA211, small stud diodes, small enough to allow for both chassis mounting or soldering to terminals.
So they did the latter.

OK so that was a useful exercise... we basically have only two rectifiers, these two diode "strings". So since we have both positive and negative supplies, I guess we have therefore a center tap, and one diode / half wave rectification on the positive side and another diode to rectify the negative zside.

So that means all power rails must be derived from this main/single supply, they are all cascaded.

Hey.. amazing all you can deduce of the topology just by looking a what components are present...

[TERRA Operative]

Anyone seen this connector before?

https://www.eevblog.com/forum/projects/help-finding-a-plug-used-in-tektronix-thm720-handheld-scope

Trying to track it down for my messings arounds with the THS720 scopes...

[factory]

Vince, have you tried reducing the frequency & pulse width using the front panel controls, as suggested by the 214A manual?

Your parts from Mouser are on the way, I posted them after work, it was a bit close on the weight* at 245g (packed a few extra bits), with RM you can send a small parcel of 10g to 250g at the same cost.

*luckily the cheapo scales here slightly over-read.   

David

[Vince]

Vince, have you tried reducing the frequency & pulse width using the front panel controls, as suggested by the 214A manual?

Nope didn't try that... because I isolated the PSU. I removed the 3 big power cable that run from the PSU to the 3 other decks.
PSU is all alone yet it still trips the protection. Maybe I just have a bad filter cap in there that's dragging the rails down....

Your parts from Mouser are on the way, I posted them after work, it was a bit close on the weight* at 245g (packed a few extra bits), with RM you can send a small parcel of 10g to 250g at the same cost.

Cool, thanks. Can't wait to receive that and finish the restoration of that amp, at long last.....

*luckily the cheapo scales here slightly over-read.   

David

Yes my scale was reading way high as well... your parcel weighed for the RMS meter weighed at 12kg IIRC, but the scale at the post office was more like 11kg...

[factory]

The cheapo digital scales were very close to the post office one, only 2g difference, I think the Ballantine would destroy this scale. Difficult to check heavy stuff, as only have analogue scales, but those can be set to over-read by misusing the zero adjust.



P.S. accidentality bought this borked thing this morning..... 



David

[wkb]

Smells like an unhappy CPU?

[Vince]

P.S. accidentality bought this borked thing this morning..... 



David

Well at least you can salvage lots of red LEDS 

You are lucky to accidentally manage to do something... I am having presently the opposite problem : I am failing to intentionally do something.... I just packed your parts and went to the French post website to try to order your shipment on-line... once I have filled everything in and validate the form, I get " Error 500 - sorry we are having technical difficulties".... tried again ... same error.

I am so fed up with the French post.... sky rocketing prices yet plummeting service quality... doesn't add up .. 

[salvagedcircuitry]

Here you go brethren!
Agilent S-series Broken
Starting bid at a low, low price of only $24,000! 
Smoking deal!!!
It's not like the seller specializes in test equipment or anything...
It's not like the seller guarantees the functionality of other test equipment... 

https://www.ebay.com/itm/134526446662




How much do you want to bet this was in a lot of broken gear from go-dove for $500USD

As for the bid placed, I truly hope it's from a non-paying bot. If someone willingly pays that, I have a bridge to sell you. 

[TERRA Operative]

P.S. accidentality bought this borked thing this morning..... 



David

I got one of those needing one of the unobtanium hybrids but works fine otherwise.
If you part yours out, I call dibs!

If not, maybe I can part mine out if you need a part... I've been waiting for a busted one to come up cheap for ages now...

[factory]

Will do, if it turns out to be completely knackered, I was thinking of those hybrids you need when I bought it.

Smells like an unhappy CPU?

Could well be, either stuck at power up, or maybe a dead crystal (had this at work, it had shattered, not TE related though), or I noted mentions of battery or supercap leakage, with eaten traces? Had this with something before and it had wrote off the CPU board, no one on ePay wanted it as is (with honest description) so it got scrapped.

Well at least you can salvage lots of red LEDS 

You are lucky to accidentally manage to do something... I am having presently the opposite problem : I am failing to intentionally do something.... I just packed your parts and went to the French post website to try to order your shipment on-line... once I have filled everything in and validate the form, I get " Error 500 - sorry we are having technical difficulties".... tried again ... same error.

I am so fed up with the French post.... sky rocketing prices yet plummeting service quality... doesn't add up .. 

Yes lots of nice original HP LEDs, none of that Broadcom rubbish. 

I've had problems in the past with Parcelforce and their computer or telephone payment systems, trying to pay customs fees, worst thing is when it goes wrong you can't try again, it bricks the invoice number. I solved that by going to the depot every time and paying in person. This doesn't happen often these days, since the prepayment of import fees at the checkout of ePay or other shops.

David

[factory]

Some free test gear from bd139 on the radio forum, which will be disposed of, if not claimed by the end of the month; https://www.vintage-radio.net/forum/showthread.php?t=199845

He's clearly found a very temporary cure for TE addiction too;
https://www.vintage-radio.net/forum/showthread.php?t=199846

David

[Vince]

Oh, so he is giving away his nice  Tek 321A, this puppy needs to be rescued ! Can't believe it will get scrapped 

That's depressing...

[Vince]

Well at least you can salvage lots of red LEDS 

You are lucky to accidentally manage to do something... I am having presently the opposite problem : I am failing to intentionally do something.... I just packed your parts and went to the French post website to try to order your shipment on-line... once I have filled everything in and validate the form, I get " Error 500 - sorry we are having technical difficulties".... tried again ... same error.

I am so fed up with the French post.... sky rocketing prices yet plummeting service quality... doesn't add up .. 

I've had problems in the past with Parcelforce and their computer or telephone payment systems, trying to pay customs fees, worst thing is when it goes wrong you can't try again, it bricks the invoice number. I solved that by going to the depot every time and paying in person. This doesn't happen often these days, since the prepayment of import fees at the checkout of ePay or other shops.

David

Tried again this morning before leaving for work... still get their error message.
Tried again this evening.... still error.
Tried again 2 hours later... still error.
Tried using a different web browser.. still error.

I am sorry Dave... looks like they just don't want my business. 
I will keep trying every day, hoping they will fix it one day

Neomys was luckier... he is in the EU, so the guy at the post office this evening made no trouble sending Neomys' envelope.
Hell I paid even much less than I thought... because the prices listed on their website apparently "conveniently" fail to tell you about the existence of the cheapest option, they only list the expensive option, making you believe that it's all there is available... business is business I guess. Lucky the guy told me about it, there is at least one useful person in this post office... may he reproduce and have lots of kids.

[factory]

Oh, so he is giving away his nice  Tek 321A, this puppy needs to be rescued ! Can't believe it will get scrapped 

That's depressing...

Hopefully someone will rescue the 321A, it's too far away for me now, but was quite a bit nearer last year.
That very nice one in France didn't hang about long either.

There seems to be more interest on the radio forum now "free" is mentioned.

David

[m k]

I get " Error 500 - sorry we are having technical difficulties".... tried again ... same error.

Nowadays our post is delivered only every other day.
But obviously after Friday the next is Tuesday.
So you never really know, without some sort of book keeping.

[Andy Watson]

There seems to be more interest on the radio forum now "free" is mentioned.

What a bunch of misers on that forum! If I lived within sensible driving distance I would have snapped his hand off at the initial prices. Those Marconi oscillators are nice bits of kit. I've got a TF2000 on the refurb pile.

[vk6zgo]

If I wasn't on the other side of the World, I'd snap up the Signal Generator!

[Brumby]

If I wasn't on the other side of the World......

How often those words have spun around in my head, if not been uttered out loud.

*sigh*

[m k]

I'm currently wondering should I drive 20h, take a boat trip and use three days for a pickup.

I've had problems in the past with Parcelforce and their computer or telephone payment systems,

Telephone, you mean you poked those 10x10 numbers in and then smiley woman voice said you failed, transaction is over, have a nice day.
Those were the days.

[W6EL]

It ain't much but it's all mine!



Can y'all hear the fans from over there?

[Vgkid]

*snip

What is on the bench between the hp power supply , and the Tenma  power supply.
Liking the displays on that Tenma psu.

[W6EL]

That's a 7kv capacitor for a Henry 2k4 amplifier which I may some day complete. I have one 2k4 that works and one that is in pieces. I was planning to send the 8 Henry (yes) inductor to a fellow to have him rebuild it. Same fella had offered to hipot the caps, so I had those out for shipment too, but then he retired and so now it sits partially complete.

The Tenma PSU would be so much better if the meters moved properly. When it showed up at my doorstep, the seller had used empty bread sacks as package material. Yes. Bread sacks. The thing looked like it had been used for batting practice, I had to straighten the face plate out with a vice! But no amount of fidgeting with the meters seems to work, they always seem to catch somewhere and get stuck. Tap tap tap and then start swinging again.  Also FYI for anyone with these supplies, the main capacitor board is comprised of 25V capacitors, but the unregulated voltage is typically around 26V. Design margins, what are those?

[Robert763]

It ain't much but it's all mine!


Can y'all hear the fans from over there?

A very nice selection of quality capable TE. Looks to be carefully selected.
 
Plus a Tenma PSU 

[tggzzz]

It ain't much but it's all mine!

Welcome

Good start, looks like it neatly covers many uses.

Can y'all hear the fans from over there?

They wouldn't bother me even if I was standing next to them. Unfortunately