Test Equipment Anonymous (TEA) group therapy thread

[BU508A]

Incredible - mostly looks as if it just came off the assembly line! 

Agreed, that supply is clean.  It is weird about the corrosion on the fuses and no where else.

I am surprised that the maximum B+ is 300V. I would think +500V maximum would expand it's usefulness.   

That's why you have to get a second NGU. 

[med6753]

Incredible - mostly looks as if it just came off the assembly line! 

Agreed, that supply is clean.  It is weird about the corrosion on the fuses and no where else.

I am surprised that the maximum B+ is 300V. I would think +500V maximum would expand it's usefulness.   

That's why you have to get a second NGU. 

You crafty Germans. 

[xrunner]

That's why you have to get a second NGU. 

And the dots of paint on the solder, I haven't seen a lot of that over here. Is that an identifying mark to tell if tampering or repair has been done?

[BU508A]

That's why you have to get a second NGU. 

And the dots of paint on the solder, I haven't seen a lot of that over here. Is that an identifying mark to tell if tampering or repair has been done?

I have no idea. I saw similar dots like these on very rare other occations and was always wondering about their purpose. 

[Cubdriver]

That's why you have to get a second NGU. 

And the dots of paint on the solder, I haven't seen a lot of that over here. Is that an identifying mark to tell if tampering or repair has been done?

I have no idea. I saw similar dots like these on very rare other occations and was always wondering about their purpose. 

My guesses would be either to indicate tampering, or perhaps to verify QA, as in look at the joint then mark it to indicate that you have done so.  During my house rewire I used a marker to draw a diagonal line on my circuit breaker terminals as I torqued the connections as an indication that I had used the torque driver on them and done the final tightening.

-Pat

[AaronLee]

Never had or used a Sinclair product. Seems I wasn't missing anything other than aggravation. 

Same here. I took a look when I saw the low prices of their products, but almost immediately decided there was no way I'd waste money on something with such a minimal specs and obviously so cheaply made.

[Kosmic]

Hooo Boy, I snipped a big one this time (35kg/77lbs) and it's a Fluke! Please remember me to never set auction listing scheduled to end a midnight on a holiday.

Missing pictures from previous post

The waveform on TP5 when everything is working correctly.


The 2 optocouplers on the DAC board.

So I went all out and decided to replace All the optocouplers and the NAND gates (U30, U32 and U38).



Interestingly the waveform coming out of the digital section (TP5) is now a bit different.



Look like the DAC is now fixed. The calibrator is around 15ppm from my Agilent 34401a (which I think read a bit high).



The 5ft digit was also fixed at the same time. Was previously not working and was on my list of things to investigate.



I ought to do more tests to figure out which of the chip actually failed.

[Vince]

Oh great, fixed, well done 

But... but....  you changed everything at once so we will never know what the root cause of the problem was ! That is not acceptable on TEA!!   

So it's 15ppm off then ? Don't know the specs of this thing but regardless, I guess it's nothing to complain about for a XX years old boat anchor that has not been calibrated in many years I guess...

[Kosmic]

Oh great, fixed, well done 

But... but....  you changed everything at once so we will never know what the root cause of the problem was ! That is not acceptable on TEA!!   

So it's 15ppm off then ? Don't know the specs of this thing but regardless, I guess it's nothing to complain about for a XX years old boat anchor that has not been calibrated in many years I guess...

Well I want to test each chip individually.

Not sure I can really trust my 34401a. It was never calibrated. The 5101b was probably calibrated and in operation just before his failure.

[mnementh]

It's official... We are finally 100% done with the old place.

Shed is moved; I spent a hour drilling extra screws through the frame into the base, but it paid off. Nothing moved so much as a smidge all the way over; not even at 70 kliks per.

House is cleaned, keys handed off, and ex-landlord said it was all fine.

And since our cleaning service bailed on us at the last minute due to COVID-related issues, we had to clean the house from top to bottom ourselves. But we saved almost as much as I spent on the rollback wrecker getting the shed here.

mnem
*toddles off for some couch-tuber time widda boi*

[Kosmic]

It's official... We are finally 100% done with the old place.

Shed is moved; I spent a hour drilling extra screws through the frame into the base, but it paid off. Nothing moved so much as a smidge all the way over; not even at 70 kliks per.

House is cleaned, keys handed off, and ex-landlord said it was all fine.

And since our cleaning service bailed on us at the last minute due to COVID-related issues, we had to clean the house from top to bottom ourselves. But we saved almost as much as I spent on the rollback wrecker getting the shed here.

mnem
*toddles off for some couch-tuber time widda boi*

Good Job 

[tautech]

It's official... We are finally 100% done with the old place.

Shed is moved; I spent a hour drilling extra screws through the frame into the base, but it paid off. Nothing moved so much as a smidge all the way over; not even at 70 kliks per.

House is cleaned, keys handed off, and ex-landlord said it was all fine.

And since our cleaning service bailed on us at the last minute due to COVID-related issues, we had to clean the house from top to bottom ourselves. But we saved almost as much as I spent on the rollback wrecker getting the shed here.

mnem
*toddles off for some couch-tuber time widda boi*

Yeah but.....the calories lost are priceless. 

[Brumby]

Congratulations on the move.

Looking forward to the time when the decision to move is yours.

[Bud]

... so many things either worked or didn't when they arrived. If like me, you got lucky, the products worked well,

This and the 28 days delivery thing - are you talking about Aliexpress in 2021?

Edit: ...seems no one has problems with that today 40 years later.

[Bud]

Dang. Sinclair died:

https://www.theguardian.com/technology/2021/sep/16/home-computing-pioneer-sir-clive-sinclair-dies-aged-81

Just yesterday i felt the urge to watch again the "Micro men" movie... That can't be a coincidence 

[Saskia]

@mnem congrats

[mansaxel]

It's official... We are finally 100% done with the old place.

Shed is moved <snip>

Wonderful. While I admire your stamina in keeping things going while being forced to move around like so,  I sincerely hope you'll very soon get to the point where not only do you have work visas but also a chance to settle.

TE: Fluke 27 kit has left Erlanger. Still paid too much for it, but that Probe...

[tggzzz]

Dang. Sinclair died:

https://www.theguardian.com/technology/2021/sep/16/home-computing-pioneer-sir-clive-sinclair-dies-aged-81

Just yesterday i felt the urge to watch again the "Micro men" movie... That can't be a coincidence 

That is a good programme. I was in Cambridge 81-87, and it all "rang true".

[Cubdriver]

Picked up a pair of Sansui SP200 speakers (apparently made only in 1968 from what I've been able to find about them) in nice physical condition for cheap.  Of course the tweeters (all four of them) are cooked, so new ones are inbound from the Bay of Malcontent and should arrive this weekend.  Also have new caps for the crossovers.  Decided to monkey around with the 3580A spec an and try to get some curves from the crossovers before recapping, to permit comparison after the new film caps have gone in in place of the old non polarized electrolytics.


They definitely scream late 60s design aesthetic, but are in pretty nice shape cabinet wise.

The 3580A sports a handy swept signal source on the rear panel, so it's perfect for doing response curves.

(yes, it's rather grungy and needs a thorough cleaning.)

I went through and got response curves for each of the three outputs - woofer, 'squawker' (gotta love the Japanese!!) and tweeter in each of the three crossover settings (Soft, Natural and Clean), saving the 'Soft' curve of each as a reference to more clearly see the differences.


Here is the midrange in 'soft:


And 'Natural' with the 'Soft' curve below:


And finally 'Clean' again against the 'soft' curve:


Additional pics with captions at:
https://pmanning.smugmug.com/Electronics/Sansui-S200-Speaker-Repair

I may also try to get some similar curves from the 3582A Spec An before recapping the crossovers to get some practice with it, too.

-Pat

[McBryce]

In memory. Remember Clive made TE too....

McBryce.

[Robert763]

That's why you have to get a second NGU. 

And the dots of paint on the solder, I haven't seen a lot of that over here. Is that an identifying mark to tell if tampering or repair has been done?

I have no idea. I saw similar dots like these on very rare other occations and was always wondering about their purpose. 

My guesses would be either to indicate tampering, or perhaps to verify QA, as in look at the joint then mark it to indicate that you have done so.  During my house rewire I used a marker to draw a diagonal line on my circuit breaker terminals as I torqued the connections as an indication that I had used the torque driver on them and done the final tightening.

-Pat

The primary use ofthe paint is an inspection mark. As each joint was inspected it was marked. This allows the inspector to to keep track of their progress. For critical items a scond inspector would check th marks, possibly on a sample basis. Tamperproof is secondary, you can generally tell if a joint has been reworked. A case seal is lso much cheaper and easier.

On the fuse corrosion I'd posit that it was excess flux at manufacture of the fuse. This has then migrated out of the end cap and caused the corrosion.
The marks on the transformer might be mold. I'm sure I've said this before, but I tend to give anything suspect a wipe with a cloth dampened with Benzalkonium chloride solution. In the UK Dettol sell a washing machine cleaner that is mostly BZK. Handy small bottle and lemon scent. It's not as potent against fungus as bleach, but a lot safer and less corrosive.

[Robert763]

Hooo Boy, I snipped a big one this time (35kg/77lbs) and it's a Fluke! Please remember me to never set auction listing scheduled to end a midnight on a holiday.

Missing pictures from previous post


The 2 optocouplers on the DAC board.

So I went all out and decided to replace All the optocouplers and the NAND gates (U30, U32 and U38).



<SNIPPED>

Are the two opto couplers different part numbers in the original design?
While some may "complain" that to have not isentifie the faulty part, remember it may well have been parameter tolerance or drift on both the gate and opto causing the issue. Individually they may meet spec. I would not disturb that PCB an extra two times. It triples the chance of damging something or making a mistake.

[AVGresponding]

As I said, Clive Sinclair left a significant technological legacy, one way or another.

Who knows which path Chris Curry would have taken with his life if he hadn't worked with Sinclair? We can't know. What we do know is he left to found Acorn from which the mighty oak of ARM grew.

I'm sure some of you have heard of "computer games". There is a rather popular one called "Grand Theft Auto". The ZX Spectrum is what one of the founders of DMA Design (now Rockstar North, and the creator of that game series) cut his teeth on. The ZX series gave computer access to the working class, something other contemporaries reserved for the middle classes due to the cost of entry to the club.

I'm happy to raise a glass to his memory and thank him for his contribution to the world.

[med6753]

Stumbled across this. Interesting removal technique for pots.

[med6753]

Also found this. Tek quickly discovered that the RCA supplied CRT's were too variable and not precise enough.

And a few years later Tek outdid themselves with the ceramic CRT.