Test Equipment Anonymous (TEA) group therapy thread

[m k]

Add something more, and be a good guy.
Something like from a known source and so on.

[Specmaster]

QUAD 33 / 303 Vintage amps restoration

This is the end.

After many months and many Euros spent chaing parts, today I finally was able to button the pwoer amp up, wire it up to the 33 pre-amp and see what's what.

Worked fine for a few minutes then all hell broke loose. The power amp went kaput again.... again... again.

I am done, I will not repair it this time. I have better things to do with my precious time and limited money.
I am completely, completely.. fed up with this amp, I really am. 
This power amp is a pile of sh*t, I give up. It's not worth my time, I want, I need to move on... if just to preserve my sanity.

I hope I can get part of my money back even if sold for parts only...

I checked the output of the pre-amp with the scope. Seems to work fine.
I guess the "magic" happens mostly in the pre-amp not the power amp, so I should be able to get some money for the pre-amp alone, and get whatever for the defective power-amp.

I will try to see the glass half full and say that it was a learning experience. Let's call it that.

You can't fix them all I guess... some stuff just doesn't want to live, there is no point going against their will....  you gotta be reasonable and let it go at some point...

Oh dear Vince, that really is a shame, I really can assure you that Quad really is a Hi-Fi king and is highly sought after by any true Hi-Fi fan, when you say it went kaput again, what actually happened? Are sure that it is not a case of the speakers failing, they certainly don't look to me as if they could handle any real power. Did you perhaps accidentally over drove them and blew the voice coils or caused the coils to short circuit and blow the output stage or what?

Unlike most modern amplifiers, there is probably no speaker protection stages in it so it would be very easy to do damage if not careful.

If you are satisfied that the speaker are not the cause, then you must have missed something else along the way. Try it connected to a dummy load and monitor the input and the output on a scope and see how closely the two waveforms are to each other and watch for spurious spikes in the output, it would indicate other components are breaking down with in the amp itself.

[factory]

Getting somewhere with Kicad and the TE related Panaplex footprints (need to double check the NPTH size), going to build a test board.

Very good !  Thanks, now I fdo'nt have to mess around doing the same thing, you can just send me your Kicad file ! 

.. and I will just add a DIL footprint to it, wire up the traces and call it a day...

That's one messed up footprint those things have....

One must wonder what kind of a pre patent application pin arrangement study group was formed.

Very messed up datasheets too, it seems.

Datasheet I used last week;
http://www.tube-tester.com/sites/nixie/dat_arch/Sperry_01.pdf
Found another datasheet;
https://www.waynekirkwood.com/images/pdf/Sperry_Information_Displays_Catalog_1973.pdf
Oddly this datasheet gives 0.025-0.028 hole diameter for the pins, the one I used before gives 0.028-0.031. 
And fill tube dimensions are different on both datasheets, need to check which matches the devices I have, it's not the only difference in the two datasheet, display height & fill tube dimensions are also different.



Seems the large hole is not centred on the fill tube, in the Anadex counter, possibly due to datasheet error. 



Will have to finish the Kicad footprint sometime next week, hopefully I can add it here.

Close up of the slightly faulty NOS display, seems to have uneven/missing plating on the bottom segment. 



Used working one in the Anadex counter for comparison.



P.S. Friday evening was a bit of a disaster, had about 1/2" deep of water, in the workshop after heavy rain. It took several hours to clear the water, with a dumpster dived mini wet vacuum cleaner (part of carpet washer) and a mop for the rest, Saturday the roof drain was cleared of accumulated sandy mud. No TE casualties thankfully, as I know not to leave them directly on the floor, have been using wood blocks for years to prevent corrosion issues. 

David

[Robert763]

There are two clearly broken broken solder joints between the display board and the main PCB in your photo. Could that be part of the issue?

[Vince]

QUAD 33 / 303 Vintage amps restoration

This is the end.

After many months and many Euros spent chaing parts, today I finally was able to button the pwoer amp up, wire it up to the 33 pre-amp and see what's what.
Worked fine for a few minutes then all hell broke loose. The power amp went kaput again.... again... again.
I am done, I will not repair it this time. I have better things to do with my precious time and limited money.

Oh dear Vince, that really is a shame, I really can assure you that Quad really is a Hi-Fi king and is highly sought after by any true Hi-Fi fan, when you say it went kaput again, what actually happened? Are sure that it is not a case of the speakers failing, they certainly don't look to me as if they could handle any real power. Did you perhaps accidentally over drove them and blew the voice coils or caused the coils to short circuit and blow the output stage or what?

Unlike most modern amplifiers, there is probably no speaker protection stages in it so it would be very easy to do damage if not careful.

If you are satisfied that the speaker are not the cause, then you must have missed something else along the way. Try it connected to a dummy load and monitor the input and the output on a scope and see how closely the two waveforms are to each other and watch for spurious spikes in the output, it would indicate other components are breaking down with in the amp itself.

I said I was done Spec, but you want to torture me some more ? Has my agony with this amp not been long enough already (been two years now) ? You want me to suffer even more ? Don't I deserve some psychiatric rest ?

OK just because it's you, I spent a few minutes putting that bloody amp back on the bench along with the speakers.

First I tested the speakers. They are plenty enough for this amp my Spec. This amp is hardly that big a beast, and I was harldy using it anywhere near its limit, if just because my ears were right next to the speakers...
I connected both speakers to my sig gen, the old analog Philips one, it's got enough grunt to drive those speakers directly. Both speakers appear to work just fine.

What were the symptoms when it crapped out ? From what I remember, it was working fine but I had music only on one of the speakers. I swapped them and same issue. One of the outputs of the amp was not giving anything. Since I was also using for the first time a 4 pin DIN cable I had just cobbled together, to connect both amps, I though maybe I got the wiring wrong. So I tried the old "cable", and hey presto I got sound on my both speakers. So my nex cable was not wired properly it seemed, so I cracked both plugs open and checked things. But it seemed it was wired correctly, and the soldering looked OK, no accidental short between pins. So I didn't understand what was wrong with my cable. so I put it back in action, fiddling with the wires at the back of the pins while playing music, and IIRC that's when the "mishap" happened : all of a sudden I got two things happen :

1) No music anymore on one speaker.
2) On the other speaker, no music either but instead a deafening buzzing sound.

Pulled the connecting DIN cable, hence no signal feeding the power amp anymore, so should be silent... but the loud buzzing was still there.
So I called it a day. RIP.


OK so tried it again now, feeding the input with my sig gen. Result : works fine now, on both speakers.... WTF....
But I did notice that the power on light too a few seconds to come on.

So I then added the 33 pre-amp to the mix, replacing the sign gen. And that did not work, no sound at all, silent. I noticed that although the pilot light on the pre-amp did light up, the one on the power-amp did not light up at all....

Strange. So maybe a power supply issue. Will see what can I find. Maybe the fuse was a bit old and defective, and eventually just blew. I don't know if I have a spare one of the proper rating.

10PM here, I will spend a few minutes checking the power supply, but that's about it for this evening.

At any rate, I did check the solder side of the driver boards, and unlike last time, the pads and traces related to the trannystors did not lift or break / overheat, which is at least something positive. The metal work I did to replace those old obsolete trannystors may have not been in vain after all 

[Runco990]

QUAD 33 / 303 Vintage amps restoration

This is the end.

After many months and many Euros spent chaing parts, today I finally was able to button the pwoer amp up, wire it up to the 33 pre-amp and see what's what.

Worked fine for a few minutes then all hell broke loose. The power amp went kaput again.... again... again.

I am done, I will not repair it this time. I have better things to do with my precious time and limited money.
I am completely, completely.. fed up with this amp, I really am. 
This power amp is a pile of sh*t, I give up. It's not worth my time, I want, I need to move on... if just to preserve my sanity.

I hope I can get part of my money back even if sold for parts only...

I checked the output of the pre-amp with the scope. Seems to work fine.
I guess the "magic" happens mostly in the pre-amp not the power amp, so I should be able to get some money for the pre-amp alone, and get whatever for the defective power-amp.

I will try to see the glass half full and say that it was a learning experience. Let's call it that.

You can't fix them all I guess... some stuff just doesn't want to live, there is no point going against their will....  you gotta be reasonable and let it go at some point...

Vince,

Is there any chance you got counterfeit parts?  This is happening more and more.  I have been a victim of this also, especially working on power amps.  I don't know that model Quad, but does it require tightly matched transistors?  This is why I personally no longer work on Marantz or others that do.  They keep blowing up unless you can match the originals exactly.

Quad is good stuff, but spare parts leave a lot to be desired.

[Vince]

No and no, I think.

The transistors I used to replace the old unobtainium ones are 2N5320/22 which are readily available from Mouser or wherever. No need to resort to shady suppliers like Ebay and friends.

As far as matching/pairing them, I can't remember any mention of that in the service manual, nor on forums.
People who work on amps from what I see, typically no squat about electronics anyway, they would be hard pressed to match transistors anyway.

But... some news : the amp did not pop its fuse. So I tried again using the two amps in tandem.
Go figure, it worked fine    and sounded quite nice even on those crappy speakers (from a cheap Toshiba stereo system we had at home when I was a kid 35 years ago).
So I played some more, to see if a problem would occur after some warm up.
I played my Queen classics for 90 minutes and all went well.... no failure. 

I think there must be a dodgy thing going in the new interconnect cable I made (for my test I used the old crusty test cable), though as I said it appears to be wired correctly with no shorts, so I am a bit at a loss as to what could be wrong with it 

As for power issues... I think there might be a bad connection at the back of the pre-amp where the power-amp taps mains. Also there is a bit of green corrosion on the power-amp plug, which probably does not help. So I guess I just have basic dodgy wiring issues, but the amps themselves are just fine ? So maybe all the time and effort I spent on reviving that power amp was not in vain after all, and I somehow managed to do something right ?! 

... either that, or they have weird, pervert intermittent issues....

I will try to solve my wiring issues and run the amp for a few more hours, an hour here, an hour there, to try to gain some confidence in them...

If they keep working, I better sell them real fast, before they fail again and I am back to square one.  The sooner I flog them, the sooner I will be able to sleep on both ears...these amps are torturing me.

For now it's midnight here so...good night TEA.

 

[tautech]

Sleep well Vince knowing you're almost there and dream of Deoxit and interconnects. 

[Specmaster]

@Vince, those din plugs and sockets were always trouble, the socket may look OK, but they suffer from bad contacts in the pins, fit new ones to be sure, better still replace them if possible with phono (RCA) sockets and plugs to bring it upto date. The loud buzzing you heard is possibly an indication of such a connection, so you were more than likely getting a mains hum from an open ground connection.

I know you like to keep equipment original, but sometimes updating things can be a boon and give you some sanity back.

[Neomys Sapiens]

Nice box. Not really a Decade box. It looks like a BCD box. Shame it's not binary to get a bit more range out of it. Looks like 12 position wafers so won't go to 16.

When I look at how those capacitors are connected to the switches, you are obviously right.

But this is going to be a PITA now. I have characterised the box at 100Hz, 2kHz and 100kHz.
Interesting is that the worst values for 100Hz lie in the 1..9nF range, not in the lowest one.
And I have to repeat the highest range with 100kHz, as I must have made an error or I need to use another method of connection.
But nevertheless, several values are sticking out across the frequencies (for example the 10nF). The BCD circuit makes that hard to correct, because I can't exchange a single errant cap and be done with it.

Or I would have to change the labeling to MOSTLY 5%. 

[m k]

... either that, or they have weird, pervert intermittent issues....

Not unheard of.

Many angled DIN connectors have riveted connections.
Maybe you can feel/hear the problem by wiggling them one by one.

[TERRA Operative]

Yeah, +1 vote down for those DIN connectors.

Vince, be sure to give things a wiggle and a shake on the next test to see if there's something rattly or intermittent.

[Vince]

OK, today is another day....

Played a lot with my two DIN cables and associated sockets... that looks like it was indeed the problem.

My cables were both good, and the socket on the power amp looks good. The problem appears to be the output socket on the pre-amp.

Contact cleaner and some exercise and now it works fine and appears reliable, and my new interconnect cable works just fine now, yeah.

The setup is playing right now. Will let it cook for an hour or two while I am doing some work outside the house (work on the garage is resuming at last... truck(s) are scheduled on Friday to pour the concrete for the slab, yeah...).

Replacing the DIN socket for RCA connectors ? Hell no. Not that I like dodgy sockets, but I spent all that time and efforts rfixing these amps in order to flog them and make some money, hopefully.
Destroying the rear panel to fit RCA connectors is not exactly a selling point !     Most vintage "people" like their Vintage stuff looking original at least from the outside for looks and originality.
Then every one is free to destroy their amp with this or that mod... but it's THEIR choice not mine ! I am not going to make choices in the name of others and make it more difficult for me to sell them and risk getting less money.  If I destroy the amp, the seller will not be able to revert the process.... whereas if he wants to do that mod, he can.... if HE wants. It's not for me to decide for him... I am here to give him the choice to do so or not. If I do it, and I am restricting my audience to people who like my mod, whereas if I do'nt do it, I can appeal to the entire QUAD audience, improving my chances.

So, the original DIN socket shall remain for the sale, and it works fine now.


OK, so looks like after two years, these amps are finally done and ready for sale... I thought this day would never come. I have now a complete and working and tested duo... all the boxes are ticked for a good resale price 

Thanks Spec for "forcing" me to not give up on the power amp...

Now let's put it on Ebay, 1,500 Euros stating price. 2,500 reserve price.
No, I guess if I can get 150 or 200 Euros for the set, it will be OK, and I won't have lost money, and maybe made 50 or 75 Euros profit. Not worth the time and effort I spent on them mind you.

Will check market prices to figure out what I may expect from the sale.

[Specmaster]

OK, today is another day....

Played a lot with my two DIN cables and associated sockets... that looks like it was indeed the problem.

My cables were both good, and the socket on the power amp looks good. The problem appears to be the output socket on the pre-amp.

Contact cleaner and some exercise and now it works fine and appears reliable, and my new interconnect cable works just fine now, yeah.

The setup is playing right now. Will let it cook for an hour or two while I am doing some work outside the house (work on the garage is resuming at last... truck(s) are scheduled on Friday to pour the concrete for the slab, yeah...).

Replacing the DIN socket for RCA connectors ? Hell no. Not that I like dodgy sockets, but I spent all that time and efforts rfixing these amps in order to flog them and make some money, hopefully.
Destroying the rear panel to fit RCA connectors is not exactly a selling point !     Most vintage "people" like their Vintage stuff looking original at least from the outside for looks and originality.
Then every one is free to destroy their amp with this or that mod... but it's THEIR choice not mine ! I am not going to make choices in the name of others and make it more difficult for me to sell them and risk getting less money.  If I destroy the amp, the seller will not be able to revert the process.... whereas if he wants to do that mod, he can.... if HE wants. It's not for me to decide for him... I am here to give him the choice to do so or not. If I do it, and I am restricting my audience to people who like my mod, whereas if I do'nt do it, I can appeal to the entire QUAD audience, improving my chances.

So, the original DIN socket shall remain for the sale, and it works fine now.


OK, so looks like after two years, these amps are finally done and ready for sale... I thought this day would never come. I have now a complete and working and tested duo... all the boxes are ticked for a good resale price 

Thanks Spec for "forcing" me to not give up on the power amp...

Now let's put it on Ebay, 1,500 Euros stating price. 2,500 reserve price.
No, I guess if I can get 150 or 200 Euros for the set, it will be OK, and I won't have lost money, and maybe made 50 or 75 Euros profit. Not worth the time and effort I spent on them mind you.

Will check market prices to figure out what I may expect from the sale.

Hmm, not so sure that I agree with your thoughts on leaving the sockets, they are on the rear of the equipment, aren't they? If so then I seriously doubt any Hi-Fi enthusiast would care what sort of interconnect was there, so long as it was safe, neat and easy to connect and RCA is now the standard that all new equipment comes with as standard. That means whatever they wanted to connect to the system could simply just be plugged straight in without the need for dedicated conversion kits.

The other option is to look at just replacing the dodgy din socket with a nice new one that does not have the bad connection problem. I don't think you have been working on this for 2 years, maybe on and off for a few months, but 2 years certainly not, it is only a basic amplifier, not an oscilloscope or something equally complicated.

As to forcing you to re-visit it again, you're welcome, sometimes we all need a nudge to look at things from a different perspective. You already did the electronics part of it, so the next logical thing was the basics, the interconnects etc. They are both electrical and also mechanical, and you cannot get access to the inner connections to examine their condition, they are prone to wear and mechanical knocks etc, so they were the next logical thing to look at. The problem you had, was that you had overlooked the basics and gone straight in at the deep end and were so committed that once you had exhausted the electronic angle, your brain was then fried and locked into thinking it was again electronic related. Again, we have all been there and anyone who tries to tell you otherwise is not being honest, either with you or themselves, fact.

Oh, as to not making much money to cover the time you put into it, that is not the way to look at it, it is the journey you had, doing things you love and will have learnt new skills along the way and you will recover with ease, any money you had to put into it.

[Specmaster]

Just stumbled upon this spotless railway in France, so clean in fact that it is a clean room and is used to connect 2 other clean rooms on opposite side of a road way, very interesting.

[Vince]

Coooool.... 

[BU508A]

Received today some vacuum glass resistors from Bulgaria, manufactured in the USSR.
Values are 100MOhm, 1GOhm, 10GOhm and 100GOhm. All resistors are rated with a +/- 5% tolerance.

Here are some pictures:

Overview:


100MOhm


1GOhm


10GOhm


100GOhm


I've bought them on ebay from this seller (NAWTS):
https://www.ebay.de/str/mlelectronics

[Neomys Sapiens]

If you want a good laugh, call up this item:
https://www.ebay.de/itm/155544624851

and then look at the third picture for the authors' names!
 

[duckduck]

Received today some vacuum glass resistors from Bulgaria, manufactured in the USSR.
Values are 100MOhm, 1GOhm, 10GOhm and 100GOhm. All resistors are rated with a +/- 5% tolerance.

Here are some pictures:

Overview:

<SNIP>

OK, I'll bite. What are some typical applications for high GOhm resistors?

EDIT: To clarify, I'm looking for an excuse to buy some .

[Vince]

Pico ammmeters ? Or femto am-meters or atto-ammeters.... or " I am counting the electrons one by one " ... - meter.

Or a series resistor to light up an LED from a lightning....

Anyway these resistors are cool, I didn't know this type existed, learned a little something today. 

[Robert763]

They appear to be clones of a Victoreen design. As stated, low current amplifiers. The mass market application was in ion chamber radiation meters.  One thing to note is that they typically have a very high resistance change with applied voltage. Trying to measure them with conventional high voltage megohmeters will give strange results.
They are totally useless as voltage dividers. Ask me how I now 
This paper is interesting.
https://apps.dtic.mil/sti/pdfs/ADA316086.pdf
They did "soak" them at high voltage to check for polarisation effects but only tested the resistors with 1V applied.

Robert.

[Robert763]

The sellers claim that they are "HV" seem to be baseless. Probably just an assumption.
I have a selection of them and electrometer valves. If anyone wants some they wuld be a lot less tha the ebay seller.

Robert.

[BU508A]

OK, I'll bite. What are some typical applications for high GOhm resistors?

EDIT: To clarify, I'm looking for an excuse to buy some .

There are two major applications here: curiosity and wanting. 
And I thought, I could do some experiments with my Keithley 616.
And, who knows, maybe one day I'll have a pico amperemeter here as well. 

And since when do we need here an excuse to buy nice and interesting things besides "I'd love to have that!" 

[TERRA Operative]

Has anyone got some 28F008 (28F008-120) 8-MBIT (1-MBIT x 8 ) 5 volt flash memory chips in TSOP-40 package? I needs a few, and the ebay seller I am taking a punt on has yet to mark as shipped after 2 and a half weeks...

Or is there any equivalent, or larger size that's more obtanium that can be dropped in, etc?

[Calambres]

Look what I've found at my late father in law's shop:



The guts:





and it can even stand up on its feet 



Poor accuracy in DC but quite precise in AC. That's what I call a vintage voltmeter!