Test Equipment Anonymous (TEA) group therapy thread

[bd139]

https://www.national-lottery.co.uk/games/euromillions   

Not a gambler .

And add the sharks!

with lasers

on their frikkin heads 

How much?!? On yer bike matey!

https://www.ebay.co.uk/itm/PHILIPS-OSCILLOSCOPE-2-CHANNELS-100MHz-PM3065-MX-9059/184207705957

 

LOL no way. Where do they get this pricing from? Their anus?

Today's purchase just arrived - very happy with this - stands at 45 degree angle so can sit on the floor for bench stuff isolation from computer stuff

[med6753]

Well surprise, surprise. Unsoldered both ends of the delay line and guess what? It's not open. Both center conductors are OK. So something is screwy with the connection to the vertical board. Investigating.....

[bd139]

Is it like the 465 delay lines ie the line is socketed but the rest is soldered? I’ve unbuggered a couple of them just by pulling and soldering them again.

Edit: also Pomona clip leads FTW

[med6753]

Is it like the 465 delay lines ie the line is socketed but the rest is soldered? I’ve unbuggered a couple of them just by pulling and soldering them again.

Edit: also Pomona clip leads FTW

Yep, exactly like the 465/475 delay lines. Checking out what's FUBAR'ed right now.

[Zucca]

FLUKE 87 FTW too!

[med6753]

FLUKE 87 FTW too!

The 87 is ALWAYS the first grab. 

[mnementh]

One of their best early circuit designers (Dick Ropiequet) was actually a chemist by trade.

At the risk of making a strawman argument...

One of the best circuit designers I knew was a biochemist by training. Another highly competent engineer (both theory and practice) didn't have a degree.

Unfortunately such experiences does lead some people to claim that you should recruit biochemists and people without degrees

Actually, the chemist point makes perfect sense to me. If you can keep track of the molecular chains in a long string polymer, almost the exact same kind of thought process as tracking a hundred different circuit paths on a PCB and schematic. 

mnem
 

[mnementh]

...Like I said a million times I'm sure now; I need a house in the middle of nowhere, with a moat 

And add the sharks!

with lasers

And mentally unstable crocodiles... 

mnem
“If you can see your neighbors from your porch, they’re too damned close.” ~ grandmomma

[WastelandTek]

Well surprise, surprise. Unsoldered both ends of the delay line and guess what? It's not open. Both center conductors are OK. So something is screwy with the connection to the vertical board. Investigating.....

Kind of expected that, I have to say

[mnementh]

Well surprise, surprise. Unsoldered both ends of the delay line and guess what? It's not open. Both center conductors are OK. So something is screwy with the connection to the vertical board. Investigating.....

Shocking, I tells ya... 

mnem
FLUKE sez BAMMM!!!

[med6753]

And.....it's all back together. I now have good continuity on the entire delay line. Apparently sloppy workmanship on my part.


But.....the POS 485 still won't power up.  If I completely isolate the +25V from the vertical board it powers up. And guess what? The vertical board side shows +11.7V with the +25V disconnected.  I would think that should be zero. More investigating....   

[med6753]

OK, either I'm lacking some documentation in my 485 PDF manual or Tek screwed up and never published it.

See schematic. With the +25V disconnected the +24.7V DCPL reads approx 11V and the +27V reads approx 5V. The +59.4V DCPL is OK. I cannot find on the schematics the point where the +25V enters the vertical board nor the circuits to generate the +24.7V DCPL from the +25V. I believe that's the key to the issue.

Tggzzz....do you have any documentation that shows the connector where the +25V enters the vertical board and the circuits to generate the +24.7v DCPL? Thanks.

[Cerebus]

Nice. What make, where from?

[bd139]

Nice. What make, where from?

Brennenstuhl via Amazon: https://www.amazon.co.uk/gp/product/B00HW0AQFU/

Pretty good for £20.

[tggzzz]

Tggzzz....do you have any documentation that shows the connector where the +25V enters the vertical board and the circuits to generate the +24.7v DCPL? Thanks.

Nothing that you don't have.

When I had my 13V rail problem the technique I used was to print out every relevant schematic, including "power distribution 17". I then sat down with a pencil and highlighter. I slowly physically and methodically scanned the pencil across each sheet with my eye following the pencil - not skipping hither and thither. That finally enabled me to see all the 15V tant beads which I would otherwise have missed.

Hint: 17, top right, R696 and a 6.8uF 35V tant bead C696 ? 

[Specmaster]

Is it like the 465 delay lines ie the line is socketed but the rest is soldered? I’ve unbuggered a couple of them just by pulling and soldering them again.

Edit: also Pomona clip leads FTW

Yep, exactly like the 465/475 delay lines. Checking out what's FUBAR'ed right now.

You actually had the vertical board out for recapping didn't you? Double check all the connections in the area that the delay line connects to, I reckon thats where the problem is going to be found. I've never heard of a delay be open before.

[Specmaster]

FLUKE 87 FTW too!

The 87 is ALWAYS the first grab. 

Only because you don't have a Brymen BM867 

[Specmaster]

OK, either I'm lacking some documentation in my 485 PDF manual or Tek screwed up and never published it.

See schematic. With the +25V disconnected the +24.7V DCPL reads approx 11V and the +27V reads approx 5V. The +59.4V DCPL is OK. I cannot find on the schematics the point where the +25V enters the vertical board nor the circuits to generate the +24.7V DCPL from the +25V. I believe that's the key to the issue.

Tggzzz....do you have any documentation that shows the connector where the +25V enters the vertical board and the circuits to generate the +24.7v DCPL? Thanks.

I don't know for sure, but don't the interconnects between boards terminate in plugs and sockets? If so, and you can pinpoint on the PSU where the +25 is generated, then surely, with that Fluke 87 on continuity mode, you should be able to track down where it terminates on the end of the looms that you have unplugged from the vertical board? Then you can see what bastard tants are on that circuit and replace them?

[med6753]

I don't know for sure, but don't the interconnects between boards terminate in plugs and sockets? If so, and you can pinpoint on the PSU where the +25 is generated, then surely, with that Fluke 87 on continuity mode, you should be able to track down where it terminates on the end of the looms that you have unplugged from the vertical board? Then you can see what bastard tants are on that circuit and replace them?

I know exactly where the +25V enters the vertical board. What is missing from the schematics is how the +25V becomes the +24.7V DCPL which is in turn fed to the final vertical amplifier. And this time it's not any bad tants. This was the original vertical board that was functional when I took it out to replace with the board from the parts mule. I wanted to see if I could cure a peaking issue. The replacement board had this same issue. The +25V would not come up. I put the old board back in and I have the same symptoms. It's not the PSU. I strongly suspect I somehow damaged U660 on both boards. If I did it's a done deal fail. U660 is unobtanium and the last price I saw for one was $75. 

[AVGresponding]

A pox on people that put random sticky labels on things!   

Now cleaned, acclimatised, and powered on:




That's using a big ass 220k resistor as a load, probably 7W or so. I did discover it won't switch the output on unless there's a load. It senses the load by ramping the voltage on very slowly until it sees it, no load you get about 3VDC before it shuts off. It takes several seconds to reach 300VDC.

Next I tried a 47k 5W:




The load regulation seems... well ok I guess, the metering is not that great. Haven't checked for noise yet, my scope probes are only rated for 300V and I want to think about it a bit before I jump in and fry anything.

[Specmaster]

I don't know for sure, but don't the interconnects between boards terminate in plugs and sockets? If so, and you can pinpoint on the PSU where the +25 is generated, then surely, with that Fluke 87 on continuity mode, you should be able to track down where it terminates on the end of the looms that you have unplugged from the vertical board? Then you can see what bastard tants are on that circuit and replace them?

I know exactly where the +25V enters the vertical board. What is missing from the schematics is how the +25V becomes the +24.7V DCPL which is in turn fed to the final vertical amplifier. And this time it's not any bad tants. This was the original vertical board that was functional when I took it out to replace with the board from the parts mule. I wanted to see if I could cure a peaking issue. The replacement board had this same issue. The +25V would not come up. I put the old board back in and I have the same symptoms. It's not the PSU. I strongly suspect I somehow damaged U660 on both boards. If I did it's a done deal fail. U660 is unobtanium and the last price I saw for one was $75. 

The info you seek is on page 163 of the manual

[Specmaster]

A pox on people that put random sticky labels on things!   

Now cleaned, acclimatised, and powered on:




That's using a big ass 220k resistor as a load, probably 7W or so. I did discover it won't switch the output on unless there's a load. It senses the load by ramping the voltage on very slowly until it sees it, no load you get about 3VDC before it shuts off. It takes several seconds to reach 300VDC.

Next I tried a 47k 5W:




The load regulation seems... well ok I guess, the metering is not that great. Haven't checked for noise yet, my scope probes are only rated for 300V and I want to think about it a bit before I jump in and fry anything.

You need to grab yourself a differential probe for high voltage probing with a scope, you can sometimes grab a bargain on eBay, I grabbed one a while back that will allow probing of up to a max 1000V or 600V ac/dc CAT 3. for not a lot of cash.

[med6753]

I don't know for sure, but don't the interconnects between boards terminate in plugs and sockets? If so, and you can pinpoint on the PSU where the +25 is generated, then surely, with that Fluke 87 on continuity mode, you should be able to track down where it terminates on the end of the looms that you have unplugged from the vertical board? Then you can see what bastard tants are on that circuit and replace them?

I know exactly where the +25V enters the vertical board. What is missing from the schematics is how the +25V becomes the +24.7V DCPL which is in turn fed to the final vertical amplifier. And this time it's not any bad tants. This was the original vertical board that was functional when I took it out to replace with the board from the parts mule. I wanted to see if I could cure a peaking issue. The replacement board had this same issue. The +25V would not come up. I put the old board back in and I have the same symptoms. It's not the PSU. I strongly suspect I somehow damaged U660 on both boards. If I did it's a done deal fail. U660 is unobtanium and the last price I saw for one was $75. 

The info you seek is on page 163 of the manual

Wow.....how did I miss that. Thanks. 

[Specmaster]

@med6753 Here is the parts location, close to U660 on the vertical board.

Edit: To be fair to Tggzzz he did mention these parts to you but referenced page 17 so I'm wondering if you both have the full full manual or not? The one I just downloaded has 192 pages and is the Rev B, March 1976. and if you want me to email it across to you, give me your email address and its yours my friend.

[bd139]

Not TE related ... is it ever?

So our prime minister has just explained that some of us will probably die after his party just spent years destroying the NHS, the company I work for has just closed office and everyone is working from home effective immediately, I just ordered 150 canned goods from the supermarket and I'm sitting chilling to this glorious combination:

Entertainment:



Snacks:



Armageddon fucking rocks so far