Test Equipment Anonymous (TEA) group therapy thread

[Zenith]

Nice touch, when professional forum members do admit mishaps. Makes rookies feel less humble.    

It's been said that an expert in a field is someone who has made every mistake that there is to be made in that field.

Another one that comes to mind is, "A man who never made a mistake never made anything".

Nonetheless, you can kick yourself for some of the things you've done.

[factory]

Some time ago I bought my first HP 180A, it was in quite poor condition and I had started by fixing the PSU board, it then got parked for a few years. https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3196300/#msg3196300

Yesterday I decided to put the PSU board back in and see if it would work, which of course it didn't, the -12.6V was nearer -20V, another one of the 4-074 trannystors had died while it was waiting for reassembly.



While I was testing & repairing the PSU I had the HT oscillator fuse pulled, I had also replaced a very dead & crusty open circuit capacitor.



The fuse was refitted and I was rewarded with absolutely nothing on the CRT, not even the background illumination. The voltages around the HT regulator were all wrong and there was no waveform present at test-point 7.

At this point I decided to pull the board to remove Q303, but the HT lead was preventing me moving the board, it was more difficult to remove than normal, I thought this was the rubber cap having gone hard with age, but no it turned out to be filled with silicone sealant. 





After removing this I noticed a major problem, a crack in the CRT starting from the HT connection.  Unfortunately I think this is probably the end of the line for this one, unless a replacement P7 CRT can be found to replace the dead one.



David

[tggzzz]

Nice touch, when professional forum members do admit mishaps. Makes rookies feel less humble.    

It's been said that an expert in a field is someone who has made every mistake that there is to be made in that field.

That's an impossible definition.

A sensible definition might be  "an expert in a field his someone who only makes new mistakes in that field".

[squibby]

wahaha,  just joined and found this 'group therapy' thread for test equipment.

I understand completely, started fixing old radios, then thought a tube tester would be handy, then thought... maybe a capacitor checker too... and then an old analogue multimeter would be nice... and before I know it, a whole wall in the garage is dedicated to ancient mid-century electronics test gear in various state of repair/refurbishment. 

So much fun. I like electronics with thermionic tube valves and any equipment from similar era. I should post some money shots next time I log on...

[tautech]

wahaha,  just joined and found this 'group therapy' thread for test equipment.

I understand completely, started fixing old radios, then thought a tube tester would be handy, then thought... maybe a capacitor checker too... and then an old analogue multimeter would be nice... and before I know it, a whole wall in the garage is dedicated to ancient mid-century electronics test gear in various state of repair/refurbishment. 

So much fun. I like electronics with thermionic tube valves and any equipment from similar era. I should post some money shots next time I log on...

It would be rude not to and in these cases, double posting is to be encouraged.
https://www.eevblog.com/forum/chat/whats-your-work-benchlab-look-like-post-some-pictures-of-your-lab/

[factory]

Slight distraction from starting work on the HP meter calibrator.

Inaccessible mains suppression bombe...



...Plan B, DC input.



David

[factory]

unknown

The unknown in the pictures from the last few pages, it's not one I recognise, probably US made, I thought maybe a Dana DMM, but probably not?

David

[TERRA Operative]

Anyone here happen to have a copy of the 4263B Adjustment Program, part number 04263-65005?

Keysight Japan just stonewalled me with a corporate 'Piss off, we don't sell that crap anymore'...
Anyone able to send a request to Keysight (or a friendly representative) in their country?


I want to rewrite it in Python if possible so I (and others) can recalibrate these instruments more easily.

[EggertEnjoyer123]

I accidentally obliterated one of my push button switches on my Tek 2236 when I cleaned them by putting the contacts in backwards.
Here's my solution (since I couldn't find a similar switch on the internet). It barely fits but it seems to work. I'm going to glue everything together tomorrow.
Considering that there's no current mode on the DMM, and all currents should be tiny, there should be no safety issues here.

[m k]

Slight distraction from starting work on the HP meter calibrator.

Inaccessible mains suppression bombe...

Packed or integrated, maybe somewhere in the middle.

unknown

The unknown in the pictures from the last few pages, it's not one I recognise, probably US made, I thought maybe a Dana DMM, but probably not?

David

From USA yes, but I'd say a fringe of a fringe compared to Dana.
Serial is a bit over 200 and first company takeover is from LBJ era.

Seems that nobody in the know is activated from the outer rim.
Maybe there are none.

How usually missing option has a different button face?

Spring is clearly happening,  we had enough Sun for digits.
(first wipe then picture, must remember next time)

[factory]

Some time ago I bought my first HP 180A, it was in quite poor condition and I had started by fixing the PSU board, it then got parked for a few years........


........After removing this I noticed a major problem, a crack in the CRT starting from the HT connection.  Unfortunately I think this is probably the end of the line for this one, unless a replacement P7 CRT can be found to replace the dead one.



David

Well this is unexpected, the 180A CRT which appears to have a crack still has some of the getter  , the main heater is intact, but the flood gun heater is open.



I decided to look at the EHT failure a little more, turned out the Zener between Q302 & Q303 was shorted, a 6.8V Zener was fitted for testing as 7V isn't a standard value, also replaced the two rusty neons on the EHT board, we now have a large dot (no plug-ins fitted ATM). The dot is currently stuck at one side, or off screen, will try a plug-in tomorrow & see what happens.



I should probably post a warning, about wearing appropriate PPE when handling CRTs, especially ones with defects such as this one.

David

[wkb]

People who have no clue have no business mucking around inside T&M equipment. We should allow evolution to do its thing, Darwin Awards and all that 

 

[factory]

Your probably right, the warnings are in the manual too, which they probably wouldn't bother to read.

At some point I'm going to have to figure a safe way of dealing with the cataract problems, that these older CRTs have, but this one won't be one of them.

David

[shakalnokturn]

Wow that's cool !  Yes, let's team up to rescue this puppy ! 
It's in excellent nick inside out, and clearly is in working order.
Even at 400 it's still a fair price these days, for such an example.
Still a bit expensive for my purse though.

Here is the plan :

1) Figure out the dates at which you will be visiting your parents. I assume (?) you will spend at least a night there, because you love your parents so much and you want to sleep in your old bedroom for a bit of nostalgia. This means you have not one but wo dates at which we can arrange a meet with the seller. That's more flexibility, more chances that we can arrange something with the seller.

2) 10 days before the first of the two dates, the drive down, contact the seller to see if a meet is possible.

3) If so, let's try to bargain him and offer him 300 Euros. You said it's not the first tie he puts it up for sale, and he already lowered the price. So it means he has already acknowledged the fact that he won't be able to sell the thing easily/quickly, nor will he be able to make as much money as he thought. Plus of course he knows, like everybody else, that we live in shit times where the average joe has zero money.
So, he might well accept 300 Euros right now and be done with it, be off-loaded of this boat anchor, rather than be stubborn and leave it at 400 and likely not sell it at all, or not before a year or two...

4) I send you half the sum via Paypal, we are co-owners.

5) You play with it for a bit and once you are bored with it, I send you the remaining 150 and I become the full owner of this beauty 

6) Then we have plenty of time to arrange a way to get it to me.... maybe you will visit Saint-Nazaire one day, and we can meet !
OK not likely, sounds like you are more of a guy with ties in the south...


What do you say, sounds like a plan ?! 

1: I'll be out for a couple of days for sure. No nostalgia, it isn't the place of those days . I'll be giving us 2 chances to grab it one on the way there one on the way back, being on different days that's not too bad.

2: I'll try to do that maybe a week ahead so nudge me around April 5th if I look dead.

3: I re-checked my archives, it was a Tek 576 he was initially selling for 950€ I think I got confused with this one. Over the THS720 it took him some time to drop his price, but if it gets that far I'll definitely try to work the price of the 575 down.

4: Depending on need.

5: The risk is I don't get bored... Ideally I'd prefer something not quite as bulky and with a computer interface though. So yes, there's a fair chance I'll pass the boat anchor on sooner or later.

6: We should meet some day, no visit to St Nazaire planned. There are plans to travel at least towards Angers sometime this summer.

I'm not promising anything, wait and see.

[Vince]

2: I'll try to do that maybe a week ahead so nudge me around April 5th if I look dead.

I just put a sticky note o my computer screen to remind me of reminding you ! 

6: We should meet some day, no visit to St Nazaire planned. There are plans to travel at least towards Angers sometime this summer.

Hey I grew up in Angers ! 
Well, in Saint-Barthélémy d'Anjou to be more precise, a neighbouring village on the east of Angers, touching it.

I still go there once a year for New years day to visit the old man. Well except this year 'cause I was sick.

I have maybe a trip planned towards the south / you =  Might visit a retired electronics engineer in Niort, that would put me closer to you, though I forgot where you live exactly... memory has never been my strongest point.... 

But Angers is fine, it's "just" 150kms from me, 1H30 motorway trip... and half my wallet worth of petrol and outrageous forever increasing motorway tolls....

[shakalnokturn]

One piece of addiction that I collected today, and just opened out of curiosity.
Non conductive, non corrosive black goo and a dead battery. (I buy dead equipment to justify the need for another DMM once in a while  )
I don't feel too worried about the goo but haven't researched how much good news or right PITA this dead battery could be...

[EggertEnjoyer123]

I finally fixed my Tek 2236
Here's a list of all faults:
1. Bad power supply transistors which blew up.
2. Bad ceramic capacitor on the voltage feedback circuit for the TL494, which leaked current and prevented the preregulator circuit from operating
3. Bad ground connection to the CRT shield, which caused excessive noise to appear on traces
4. Bad switch contacts for the multimeter section
(I also accidentally obliterated one of the switches there, but that was my fault).

I swapped out the offending 1000pF ceramic capacitor with a 3kV one, and I swapped out the bad transistors with the TIP41C (It turns out that I was correct about the fT of the MJE15030 being too high - with the TIP41C I never observed 1MHz oscillations). I also covered the CRT shield with copper tape and I soldered a wire from the copper tape to ground. Finally, I cleaned the switches with IPA and I relubricated them. Everything seems to work now.

[wkb]

One piece of addiction that I collected today, and just opened out of curiosity.
Non conductive, non corrosive black goo and a dead battery. (I buy dead equipment to justify the need for another DMM once in a while  )
I don't feel too worried about the goo but haven't researched how much good news or right PITA this dead battery could be...

Oh, fond memories: 68020 and its FPU brother the 68882. The latter was really expensive it is day.

[duckduck]

wahaha,  just joined and found this 'group therapy' thread for test equipment.

I understand completely, started fixing old radios, then thought a tube tester would be handy, then thought... maybe a capacitor checker too... and then an old analogue multimeter would be nice... and before I know it, a whole wall in the garage is dedicated to ancient mid-century electronics test gear in various state of repair/refurbishment. 

So much fun. I like electronics with thermionic tube valves and any equipment from similar era. I should post some money shots next time I log on...

Welcome to the club! There is much love for tubes and wobbly-needle displays in here, and everyone appreciates pictures of test equipment.

[factory]

A bit more progress with the HP 180A, trying a set of untested plug-ins I still had the trace stuck off to the right, some voltage checks found yet another bad 4-071 transistor Q205 (completely open), replacing this moved the trace slightly to the left but not enough.

More voltage checks I found 100V on both sides of diode CR209, the diode was fine, but the 22.1k resistor R271 was nearer to 1.5M, the one for the opposite amplifier circuit R234 was also bad, measuring at 33k.
Once these were replaced the trace was able to fill the screen. These are both 1/2W 1% metal film resistors, being run at 0.4275W, not much derating, similar size resistors seem to fail often in the PSUs of some HP scopes.



I didn't manage to get a picture of the trace with the focus set correctly, as it's now got a intermittent problem where the trace disappears once everything has warmed up. The trace is not good either, it's not flat, this could either be the plug-ins, or maybe the plates in the CRT are bent, it may have been dropped at some point, the plastic carrying handle on older HP 180As in known to snap without warning, one of the feet is broken from the too.



David

[salvagedcircuitry]

I clearly have a scope problem.....
$95 total for a portable agilent isolated scope? Boy that's one hot temptress
The scope came disassembled, missing screws and did not fit well together.
Luckily an isopropyl cleaning, a new CR1616 CMOS battery, a complete disassembly + rebuild later and the scope booted!
It didn't come with a battery or charger, and the nicely made portable scopes love to have superbly long DC jacks, so I sacrificed a threaded DC jack that was just long enough.
Who would have thought hoarding dozens of 12v ac adapters would pay off?   
I tested it against the dsox waveform output and it looks right on the money.
Sure the U1604a wasn't one of agilent's most notable products, but less than $100, that's a win all round 

[factory]

I've reassembled the HP 180A for now, as there are other things I want to work on, I've gone as far as I can at the moment, the working AVO with 3kV range needs retrieving from wherever it's hiding, to check & set the EHT (2950V adjustment). I've confirmed the horizontal amplifier & CRT plates are fine, using a known good set of plug-ins.

The intensity pot is knackered, it's supposed to be 10k but measures in at over 40k, with a temporary replacement I have better control over the intensity, but it seems to be set very high somewhere else, minimum is way too bright. Also I still have the intermittent fault, where the trace is lost once everything warms up, this happened much quicker once I re-fitted the covers.



All the faulty parts from this round of repairs.



David

[squibby]

It would be rude not to and in these cases, double posting is to be encouraged.
https://www.eevblog.com/forum/chat/whats-your-work-benchlab-look-like-post-some-pictures-of-your-lab/

Well... if you say so.

looking as messy as it usually does. It's in the garage so I don't have to tidy up everytime I switch the lights out.


And my personal favourites:
This very beat up 1940's Capacitor checker. The panel had all this patina, the transformer was stuffed, it was rusty inside and pretty much every component was stuffed. I had to Completely rewire it. The only survivors were the switches and potentiometers. Having said that, this thing measures a capacitor's value (up to 70uf) as good as any multimeter that I have. It's not too shabby at measuring resistance also, and the capacitor checker will pump out just shy of 500V DC which is really useful for checking high rated caps for leakage. It's such a fun tool to use, I try to give it a workout as much as I can. I don't replace caps 'shotgun' anymore since I started using this. It's suprising that occasionally a 1960's cap will test perfectly, and then the same cap in the same model of stereo from somewhere else will be wrecked.


And I love the Tek 545B from the 60's. It absolutely destroys the japanese 1980's scope below it and is the is probably the highest quality object I own full stop, never mind the best instrument. Over a hundred valves, thousands of components and all hand soldered with silver onto ceramic strips that fold out for maintenance. It was fit for the space race, it was fit for aeronautics, and it'll still work in a hundred years. I'm not sure we'll ever see the like of this kind of quality ever again. It cost the equivalent of about $35,000 AUD in today's money. 50 years lates it's Mine for only $300 and connected to a pair of $15 probes from ebay

[pdenisowski]

Nice touch, when professional forum members do admit mishaps. Makes rookies feel less humble.    

Oh, I could tell you some stories ....

[med6753]

And I love the Tek 545B from the 60's. It absolutely destroys the japanese 1980's scope below it and is the is probably the highest quality object I own full stop, never mind the best instrument. Over a hundred valves, thousands of components and all hand soldered with silver onto ceramic strips that fold out for maintenance. It was fit for the space race, it was fit for aeronautics, and it'll still work in a hundred years. I'm not sure we'll ever see the like of this kind of quality ever again. It cost the equivalent of about $35,000 AUD in today's money. 50 years lates it's Mine for only $300 and connected to a pair of $15 probes from ebay

If you want to keep that Type 545B running flawlessly I recommend you perform a total re-cap of the electrolytic capacitors in the PSU. I've done a similar Type 535A as well as two Type 547's, a Type 503, a Type 516, and numerous others. Yes, it's a daunting and time consuming task but the results are worth it. I posted a link below of a recent restoration of a Type 516. The methods used can easily be applied to your Type 545B. If you have questions I'd be glad to answer them.

https://teanonymous.com/f1/viewtopic.php?t=246