Test Equipment Anonymous (TEA) group therapy thread

[neo]

The fluke 8000A is a strange, mythical, beast. I think i just blew up a second one while trying to service it. No predefined test points, no regulation and a complete lack of common sense in design.

[bd139]

The 8000a was a turd in the design department for sure. Four big problems:

1. Weak ass ASICs
2. Crap power supply.
3. Mains running right to the front panel on the board (watch your fingers).
4. Terrible display design and board.

[med6753]

The 8000a was a turd in the design department for sure. Four big problems:

1. Weak ass ASICs
2. Crap power supply.
3. Mains running right to the front panel on the board (watch your fingers).
4. Terrible display design and board.

1. Agree
2. Absolutely
3. Agree
4. Terrible display? How so? It is nearly identical to the 8600A and 1900A. Besides, I love the warm glow of ruby red LED's. 

 

[tggzzz]

3. Mains running right to the front panel on the board (watch your fingers).

Mains? Is that All?

Look at  a Tek 1502 and you will see the CRT's usual focus and brilliance controls on the front panel. Unlike in, say, the 4xx series, there is no long pole between the knob and the pot that's at 2kV. Yup, there's 2kV right behind the front panel.

Then think about using it in the way intended, or storing it under a foot of water...

[Rbastler]

Keithley 614 from Ebay

Since I saw FeedbackLoop's repair video on a Keithley 614 I wanted one.
So about a month ago I found that dirty looking 614 on ebay.com. There were no electrometers cheap and in a ok enough condition to buy anywhere in the EU. So this dirty not working Keithley 614 from 'Murica was my best bet. It displayed random numbers and remembering from FeedbackLoop's repair video, dirty switches could be the cause. And after the seller offered a 25% discount on it, I had no more doubts and bought it. With shipping and customs fees, still a good deal....if I can get it to work.
It took quite some time to ship to me, stupid customs took twice as long, as it took from 'Murica to Austria. Anyway, I immediately cleaned the switches and nothing changed. So I measured all the voltages and they have failed quite catastrophically. +30V was around 15V, -30V was -15V, + 5V was 2V and -5V was +4V. Bad caps alone can't do this, so I changed the LM317 and 7805 too, and all the voltages were ok again!
I call this a "Shariar Moment". I bought a item, broken and in bad condition and it was easy to fix
I know Shariar can't choose the failure mode of the stuff he buys, but the amount of luck he has sometimes is just incredible ^^

I will change the two lug triax to a three lug triax, since all my cables and adapters are three lug triax. I might also replace the lead acid batteries. I can buy the exact brand and model.
Plus I will mount a heatsink on the 7805, since it might have died because of overheating.
I will of course calibrate the instrument.

[xrunner]

Oops! I did it again...

I was watching an auction (mistake #1) for one of those new-fangled rubber-buttoned HP 3456A that URI corrupted me with (thanks, URI). It's supposedly a for-parts unit, and the price was still increasing with 18 watchers standing by for a snipe-o-rama tomorrow. Then, I saw a new listing for one that has rack ears and handles instead of feet, but is guaranteed to be working for a few bucks more, BIN. So, I bought it now.

Oh I just got up and saw this - nice pickup!

Of course, it goes without saying that I don't really need more voltmeters. However, I have to keep my TEA membership valid somehow.

TEA membership - use it or lose it! 

[Berni]

Nice one.

My Keithley electrometer turned out to have a dead transformer winding and additionally got a damaged quartz crystal in shipping. Managed to eventually fix it and yes the 2 lug triax is a pain.

[bd139]

Bad day here.

Replaced everything. All good. Half way through celebrations something just exploded! Taking it to bits again

[med6753]

Bad day here.

Replaced everything. All good. Half way through celebrations something just exploded! Taking it to bits again

The 475?

[Wolfgang]

A hidden tant ? or some other type of time bomb cap like a RIFA ?

[bd139]

2235. I have replaced all the RIFAs!

Sounded like a short arc. May have just been a shitty old fuse as well.

[bitseeker]

Keithley 614 from Ebay

Since I saw FeedbackLoop's repair video on a Keithley 614 I wanted one.

I remember that one. I like watching his repairs, too.

...

So I measured all the voltages and they have failed quite catastrophically. +30V was around 15V, -30V was -15V, + 5V was 2V and -5V was +4V. Bad caps alone can't do this, so I changed the LM317 and 7805 too, and all the voltages were ok again!
I call this a "Shariar Moment". I bought a item, broken and in bad condition and it was easy to fix
I know Shariar can't choose the failure mode of the stuff he buys, but the amount of luck he has sometimes is just incredible ^^

Yeah he does seem to get a good share of the "I can't believe that's all that was wrong with it" test gear, much to his own dismay wanting to create a more interesting video.

I will change the two lug triax to a three lug triax, since all my cables and adapters are three lug triax. I might also replace the lead acid batteries. I can buy the exact brand and model.
Plus I will mount a heatsink on the 7805, since it might have died because of overheating.
I will of course calibrate the instrument.

Let us know what you end up using for all those, especially the triax replacement. There was a thread before about it and lots of off the shelf ones didn't seem to fit well.

[bd139]

2235. I have replaced all the RIFAs!

Sounded like a short arc. May have just been a shitty old fuse as well.

Found it. Stuffed a new fuse in and looked for the explosion. Main switching MOSFET 

[Wolfgang]

... at least MOSFETs are available and cheap. Hope it did not die because of another failed component that has niot exploded (yet). 

[Specmaster]

What is it with old Tek scopes? They all seem to have problems that other makes don't seem to suffer with?

[mnementh]

What is it with old Tek scopes? They all seem to have problems that other makes don't seem to suffer with?

They were always on the bleeding edge. There was always something made differently or scratch-custom made, because what they were designing had never been made before. The price of being the vanguard rather than the rear guard.   

There was a time when it wasn't all just hype... 

Your bench continues to fill with many colorful bits, mnem. A great way to brighten an almost-winter's day.

It is pleasing on a fundamental level to finally get around to some of the "essential" work I've been "gonna do" for years; no matter how mundane and boring the task is on its face.


My Heat-Shrink Bin Runneth Over

Similarly pleasing on a fundamental level is having a surplus of basic supplies. It always seems you have exactly the right size, or the color you want... but never both. I've gotten entirely too adept at stretching heat-shrink that extra little bit needed to fit. 

Nothing as bright as the 10ga wire will be if something goes wrong with the psu and tries to stuff 90A down it [emoji4]

Thy Volts and Thine Amps, They Comfort Me

I'm not exactly worried about that; I've pulled 200A through the 12ga cable on the right, and 75A continuous (which is pretty much all you can get out of one of these before it trips the CB) for over 10 min. What's niggling at me now is a nearly overwhelming desire to reterminate that 10-year-old 12ga set with the same CNC ends and double heat-shrink as I used on my 10ga set. 

I know for a fact I don't need to; I just reterminated it like 6 months ago due to plating wear.  So it just sits there, mocking me. 

mnem
It mocks me, and I am mocked.

[bd139]

In this case it was a bit of shitty engineering. 2A IRF710 with 400V ceiling on mains. Idiots. Looks like it had actually nuked the heatsink compound on it and had exited the SOA which was tight anyway. Kaboom!

Testing all surrounding bits now... took a diode with it by the looks. Main IC appears to have some activity and it didn’t take the primary of the transformer out thank fuck.

Finding a 6A part with 500-600V headroom next...

I prefer linear supplies with standard transistors to switchers. Less explodey

[bitseeker]

Oops! I did it again...

I was watching an auction (mistake #1) for one of those new-fangled rubber-buttoned HP 3456A that URI corrupted me with (thanks, URI). It's supposedly a for-parts unit, and the price was still increasing with 18 watchers standing by for a snipe-o-rama tomorrow. Then, I saw a new listing for one that has rack ears and handles instead of feet, but is guaranteed to be working for a few bucks more, BIN. So, I bought it now.

Oh I just got up and saw this - nice pickup!

Thanks. I still tried for the auction one, but the incumbent bidder had much more headroom in his limit. That's OK. I got one, too.

Of course, it goes without saying that I don't really need more voltmeters. However, I have to keep my TEA membership valid somehow.

TEA membership - use it or lose it! 

Yeah, no worries there, eh?

[Specmaster]

Talking of which, it's getting a bit cold here finally. I was in Machine Mart yesterday to buy a TX7 Torx (I only have TX6 and two TX8 in my set ) and there was a crazy person buying a 25KW space heater to heat up their living room because their heating had broken down. Think they'll set fire to the walls with it!

What? Was it one of those paraffin heaters with a stocking great fan in a case sort of torpedo shaped? Those things are fecking lethal, the outlet glows red hot on them and will burn anything put in front of it after a few minutes. 

[tggzzz]

What is it with old Tek scopes? They all seem to have problems that other makes don't seem to suffer with?

Nobody cares about other old scopes. When they die they breathe a sigh of relief, junk them, and get something new

[Specmaster]

In this case it was a bit of shitty engineering. 2A IRF710 with 400V ceiling on mains. Idiots. Looks like it had actually nuked the heatsink compound on it and had exited the SOA which was tight anyway. Kaboom!

Testing all surrounding bits now... took a diode with it by the looks. Main IC appears to have some activity and it didn’t take the primary of the transformer out thank fuck.

Finding a 6A part with 500-600V headroom next...

I prefer linear supplies with standard transistors to switchers. Less explodey

And easier to work on as well 

[tggzzz]

Talking of which, it's getting a bit cold here finally. I was in Machine Mart yesterday to buy a TX7 Torx (I only have TX6 and two TX8 in my set ) and there was a crazy person buying a 25KW space heater to heat up their living room because their heating had broken down. Think they'll set fire to the walls with it!

What? Was it one of those paraffin heaters with a stocking great fan in a case sort of torpedo shaped? Those things are fecking lethal, the outlet glows red hot on them and will burn anything put in front of it after a few minutes. 

In enclosed aread with poor ventilation such things will be more subtly and peacefully lethal in other ways.

[Specmaster]

What is it with old Tek scopes? They all seem to have problems that other makes don't seem to suffer with?

Dis agree, Philips and HP are always well worth repairing and in some ways better as well, just not as popular, not that being popular makes them any better in same was Ford cars are popular but they are far from the best, just good value.

Nobody cares about other old scopes. When they die they breathe a sigh of relief, junk them, and get something new

[Specmaster]

Talking of which, it's getting a bit cold here finally. I was in Machine Mart yesterday to buy a TX7 Torx (I only have TX6 and two TX8 in my set ) and there was a crazy person buying a 25KW space heater to heat up their living room because their heating had broken down. Think they'll set fire to the walls with it!

What? Was it one of those paraffin heaters with a stocking great fan in a case sort of torpedo shaped? Those things are fecking lethal, the outlet glows red hot on them and will burn anything put in front of it after a few minutes. 

In enclosed aread with poor ventilation such things will be more subtly and peacefully lethal in other ways.

How very true

[mnementh]

In this case it was a bit of shitty engineering. 2A IRF710 with 400V ceiling on mains. Idiots. Looks like it had actually nuked the heatsink compound on it and had exited the SOA which was tight anyway. Kaboom!

Testing all surrounding bits now... took a diode with it by the looks. Main IC appears to have some activity and it didn’t take the primary of the transformer out thank fuck.

Finding a 6A part with 500-600V headroom next...

I prefer linear supplies with standard transistors to switchers. Less explodey

Now you definitely wanna check/replace on GP the flyback diode, and that 1uF/400V is a VERY likely culprit given the failure mode. The chopper MOSFET in my 2230 has been chugging along for decades without a problem and barely even gets warm. Remember, it is on the other side of T906, so this probably ameliorates things somewhat.

mnem
*Off to the Buffet of the Chinese*