Test Equipment Anonymous (TEA) group therapy thread

[Cerebus]

I don't know for sure, but I think the answer to both those questions is "If you're qualified with certificates to prove it" then you can be called upon to give testimony in court.

Well, anyone can testify in court - some of the world's least qualified people do it every day. 

In the UK courts there are no particular  qualifications for giving expert witness testimony but it would be unusual for the prosecution/appellant or the defence/respondent to not demand a list of qualifications from an expert witness that they suspected had something to say that would damage their case. However, lack of formal qualification is no bar to the court accepting one as an expert witness.

I can think of two people that I know who regularly appear as expert witnesses. Professor Ross Anderson, Professor of security Engineering at Cambridge University comes, as one would expect, with a long list of impressive sounding academic qualifications. Duncan Campbell (Whoops, set off the GCHQ/NSA alarms again!) on the other hand regularly appears as an acknowledged expert witness in the same or a closely related field, but has no academic qualification in the field that he is known for providing expert testimony in.

[ch_scr]

Ok, capacitors replaced, lives again "Supposedly prone to failure" shunt resistors replaced as well. (I had them bought already, and since I'm in there...). One 1% 464R resistor was chipped and drifted to 467R. Do YOU have a 1% 464R in stock I sure did not. But luckily, on the last recycling I scored some 499R & two 6.666K 0.1%. Guess what, in parallel that makes 464.2R Better than new! But now: on one channel I replaced the discrete transistor pair with a monolithic NPN pair for better matching. It works and behaves, but: the case is an antenna for 50Hz What now? DMM says 50k case to collector and 100k case to emitter. 
I got no problem swapping the transistors back but I would like to know if there is a way 

[med6753]

Type 547 first power up. No magic smoke but we have issues.

First time power up fan started, pilot light on, tubes have filament but time delay relay never kicked in. I noticed that the OG3 VR tube for the -150V reference was not ionizing. That's not good. I don't have a replacement. Tried re-seating the VR tube and now good. Time delay kicked in but still have major issues.

All I get on the CRT is a fixed dot on the left. Can't move it vertically or horizontally. It does vary intensity as well as focus and astig which I think is a good sign that at least the HV is working. I suspect one of the PSU voltages is missing. When I performed PSU resistance checks everything appeared OK. But that's where I'm going to start troubleshooting since there is no vertical and no sweep.

Oh well.....at least there was no smoke. 


   

[bd139]

That’s a good start. Watching this one interestedly.

Also developing a backache by proxy I think 

[tggzzz]

Duncan Campbell (Whoops, set off the GCHQ/NSA alarms again!) on the other hand regularly appears as an acknowledged expert witness in the same or a closely related field, but has no academic qualification in the field that he is known for providing expert testimony in.

Ah yes, the "C" in "The ABC Trial".

Also the reporter that did a programme that I've remembered for 35 years. In it (at 6:00) he caused the former Chief Scientific Adviser to the Ministry of Defence Ronald Mason's mouth to flap open during a TV interview.

[med6753]

This
That’s a good start. Watching this one interestedly.

Also developing a backache by proxy I think 

Yea, I'm going to have to flip it on it's side again to check the PSU voltages. Don't want to overdue it and I shouldn't even be doing that so I'm going to hold off until tomorrow.

This will help your backache by proxy. 



 

[Saskia]

just got word that that male parent thing of mine bit the dust today.

I see a bloody hell of paperwork coming my way.

no effing inheritance wanted.

[bd139]

Not sure if I should be offering sympathy or congratulations. I’ll leave that one open. Take whichever is appropriate 

[med6753]

just got word that that male parent thing of mine bit the dust today.

I see a bloody hell of paperwork coming my way.

no effing inheritance wanted.

I'm sorry to hear that but I think I know how you feel. When my Father died Him and I had a whole crap load of unresolved issues which obviously never got settled. It still bothers me somewhat to this day but I feel I've moved on.   

[Vince]

Type 547 first power up. No magic smoke but we have issues.

First time power up fan started, pilot light on, tubes have filament but time delay relay never kicked in. I noticed that the OG3 VR tube for the -150V reference was not ionizing. That's not good. I don't have a replacement. Tried re-seating the VR tube and now good. Time delay kicked in but still have major issues.

All I get on the CRT is a fixed dot on the left. Can't move it vertically or horizontally. It does vary intensity as well as focus and astig which I think is a good sign that at least the HV is working. I suspect one of the PSU voltages is missing. When I performed PSU resistance checks everything appeared OK. But that's where I'm going to start troubleshooting since there is no vertical and no sweep.

Oh well.....at least there was no smoke. 

Ah great, interesting stuff going on here !

From what you said, looks like it's a solid scope that will be fixed in no time. The fundamentals are all good, CRT and transformer(s) ,  HV stuff.. the rest is the easy stuff... just needs a few hours to troubleshoot it, but sure enough it can be fixed 

So yep, first thing to do is to check all power rails for accuracy and ripple, as always.

Then right after that... before chasing red herrings... I would simply pull all the tubes (yeah, lots of them I know...), and put come contact cleaner into the sockets, and "exercise" the tubes a bit while re-inserting them. I mean, you have already witnessed that simply re-seating the VR tube was enough to bring a power rail back from the dead... so clearly the sockets/tube pins have at least a tiny bit of oxidization, enough to cause malfunction. There is no reason to believe that all the other tubes would not be in the same condition. So check the power rails quickly, takes a minute, then put some music and re-seat all the tubes with some cleaner.

Then give it another test ride, re-evaluate, report back, and start probing around to troubleshoot it... wish I was there with you to do it myself, love fixing these old things !   

[mnementh]

On The Bench This Morning:



AiO CPU Cooler Periodic Maintenance

Y'all may have noticed the dwagon hasn't been around stirring sh...tuff up this morning... I've been a little busy.

Since I have the CPU out of my PC anyways, I figured now was a good time to do periodic maintenance on the cooler in my Gaming/VR machine; this AiO has been in service for ~2 years in various iterations of this build. While these are supposedly a zero-maintenance sealed system, there really isn't any magic here; these coolers suffer all the usual depredations of any liquid-cooled PC.

The only real difference is they design the whole thing as if it were a FRU with a life expectancy of 4-6 years, or just beyond the typical 3-5 year warranty; the system is priced such that it is most cost-effective (in this case, ~US$60 delivered from Amazon) to simply replace it as a unit when any part fails. This mostly means minimizing metal parts that oxidize, and using a lot of the more durable plastics instead. That does not mean it cannot benefit from a little periodic maintenance, however.
 


These gelatinous boogers are the byproduct of the electrolysis between differing metals (copper plate vs aluminum radiator) with a conductive liquid coolant and a little oxidation as it is nearly impossible to purge every bit of air from a system like this. They tend to form in places where the liquid flow changes direction sharply or is stagnant due to some restriction; then they grow to the point they clog things.

There are probably more of these in the end-tanks on the rad; alas, there's little one can do aboot those. Even if the hoses weren't permanently attached with crimped connectors, the small diameter of the hose barbs means there's no real way to get in there and clean anything other than the hose barb itself. The flip side of this issue is that these radiators are usually hugely oversized, and can suffer a lot of lost efficiency before they fail to cool effectively.

You can see here that the rubber divider seal which is supposed to force coolant flow through the micro-fins has softened and ballooned a bit due to prolonged exposure to the coolant; not sure how much that affects efficiency of the cooling.



Removing the impeller housing lets us see the moving bits; the entire impeller is made of rubber magnet material like refrigerator magnets, and the bearing/spindle are ceramic. Interesting that this rubber magnet material is resistant to the coolant. huh.

Nice & clean in here tho, as this is where stuff is always moving.



Now I've got the service-able bits out, I'll take these to the sink and scrub gently under hot water with a natural bristle brush that can get into the micro-grooves. Testing for flow is done the old-school way once all the coolant is scrubbed out under running water; press microgrooves against your lip and see if you can blow air through them. 



Parts have been rinsed with distilled water, and are now ready to go back together. This is done as much by feel as anything; get the rubber divider seal aligned as close as possible by eye, then lay copper plate with divider plate installed against the pump and slide a little until you feel it catch the pre-existing grooves pressed into the surface of the rubber.



Then, we button it up with the original stainless steel screws.

It is important here to thread these just as you would a machine screw; by gently applying pressure and turning the screw backwards until you feel the bump of the thread that's been cut in the plastic by the screw before, then turn forward very gingerly. If you've got it right, you'll feel very little resistance as the screw goes in; if you feel any appreciable resistance, turn it backwards and try again. By developing this skill, you can reassemble screws in almost any plastic without stripping the hole out.

A'aight; time for this widdle dwagon to get back to the build.

Cheers!

mnem

[Vince]

One 1% 464R resistor was chipped and drifted to 467R.

"drifted" ? At 467 ohms it's still within spec... no need to replace it 

Well unless that chip was indicative of severe overload  rather than just external mechanical mishap ?
You are the judge of that of course... however if only for the value, then no need to replace it, still perfectly good.

[med6753]

Then right after taht... before chasing red herrings... I would simply pull all the tube (yeah, lots of them I know...), and put come contact cleaner into the sockets, and "exercise" the tubes a bit while re-inserting them. I mean, you have already witness that simply resocketting the VT tube was enough to bring a power rail from the dead... so clearly the sockets/tube pins have at least a tiny bit of oxidization, enough to cause malfunction. There is no reason to believe why not all the other tubes would not be in the same condition. So check the power rails quickly, takes a minute, then put some music and re-seat all the tubes with some cleaner.

Then give it another test ride. re-evaluate, report back, and start probing around to troubleshoot it... wish I was there with you to do it myself, love fixing these old things !   

When I cleaned the chassis a few weeks ago I did remove all the tubes in that section and sprayed the sockets as well as the tube pins with deoxit. So I was a little surprised that there was a contact issue with that OG3.   

[bd139]

On The Bench This Morning:



AiO CPU Cooler Periodic Maintenance

Y'all may have noticed the dwagon hasn't been around stirring sh...tuff up this morning... I've been a little busy.

Since I have the CPU out of my PC anyways, I figured now was a good time to do periodic maintenance on the cooler in my Gaming/VR machine; this AiO has been in service for ~2 years in various iterations of this build. While these are supposedly a zero-maintenance sealed system, there really isn't any magic here; these coolers suffer all the usual depredations of any liquid-cooled PC.

The only real difference is they design the whole thing as if it were a FRU with a life expectancy of 4-6 years, or just beyond the typical 3-5 year warranty; the system is priced such that it is most cost-effective (in this case, ~US$60 delivered from Amazon) to simply replace it as a unit when any part fails. This mostly means minimizing metal parts that oxidize, and using a lot of the more durable plastics instead. That does not mean it cannot benefit from a little periodic maintenance, however.
 


These gelatinous boogers are the byproduct of the electrolysis between differing metals (copper plate vs aluminum radiator) with a conductive liquid coolant and a little oxidation as it is nearly impossible to purge every bit of air from a system like this. They tend to form in places where the liquid flow changes direction sharply or is stagnant due to some restriction; then they grow to the point they clog things.

There are probably more of these in the end-tanks on the rad; alas, there's little one can do aboot those. Even if the hoses weren't permanently attached with crimped connectors, the small diameter of the hose barbs means there's no real way to get in there and clean anything other than the hose barb itself. The flip side of this issue is that these radiators are usually hugely oversized, and can suffer a lot of lost efficiency before they fail to cool effectively.

You can see here that the rubber divider seal which is supposed to force coolant flow through the micro-fins has softened and ballooned a bit due to prolonged exposure to the coolant; not sure how much that affects efficiency of the cooling.



Removing the impeller housing lets us see the moving bits; the entire impeller is made of rubber magnet material like refrigerator magnets, and the bearing/spindle are ceramic. Interesting that this rubber magnet material is resistant to the coolant. huh.

Nice & clean in here tho, as this is where stuff is always moving.



Now I've got the service-able bits out, I'll take these to the sink and scrub gently under hot water with a natural bristle brush that can get into the micro-grooves. Testing for flow is done the old-school way once all the coolant is scrubbed out under running water; press microgrooves against your lip and see if you can blow air through them. 



Parts have been rinsed with distilled water, and are now ready to go back together. This is done as much by feel as anything; get the rubber divider seal aligned as close as possible by eye, then lay copper plate with divider plate installed against the pump and slide a little until you feel it catch the pre-existing grooves pressed into the surface of the rubber.



Then, we button it up with the original stainless steel screws.

It is important here to thread these just as you would a machine screw; by gently applying pressure and turning the screw backwards until you feel the bump of the thread that's been cut in the plastic by the screw before, then turn forward very gingerly. If you've got it right, you'll feel very little resistance as the screw goes in; if you feel any appreciable resistance, turn it backwards and try again. By developing this skill, you can reassemble screws in almost any plastic without stripping the hole out.

A'aight; time for this widdle dwagon to get back to the build.

Cheers!

mnem

Cure for that particular affliction….

https://www.bequiet.com/en/cpucooler/1378

[bd139]

just got word that that male parent thing of mine bit the dust today.

I see a bloody hell of paperwork coming my way.

no effing inheritance wanted.

I'm sorry to hear that but I think I know how you feel. When my Father died Him and I had a whole crap load of unresolved issues which obviously never got settled. It still bothers me somewhat to this day but I feel I've moved on.

Same here. My father was quite frankly a hopeless, reckless idiot. Been a few years now but I still haven’t managed to sort it all out. He had a limited company which he bought everything he owned on as a tax dodge  . His accountant quit immediately.

[Vince]

When I cleaned the chassis a few weeks ago I did remove all the tubes in that section and sprayed the sockets as well as the tube pins with deoxit. So I was a little surprised that there was a contact issue with that OG3.

Oh, OK ! Great then, you have already done the most tedious part of the job ! 

So you can go ahead right way with the really fun stuff now, troubleshooting the thing. Can't wait...

The VR tube maybe has intermittent internal connections to the pins ?! Don't know if such a thing can happen... but at least if it dies again, you know where to look first !

So, power rails... waiting for the report ! 

[Cubdriver]

Type 547 first power up. No magic smoke but we have issues.

First time power up fan started, pilot light on, tubes have filament but time delay relay never kicked in. I noticed that the OG3 VR tube for the -150V reference was not ionizing. That's not good. I don't have a replacement. Tried re-seating the VR tube and now good. Time delay kicked in but still have major issues.

All I get on the CRT is a fixed dot on the left. Can't move it vertically or horizontally. It does vary intensity as well as focus and astig which I think is a good sign that at least the HV is working. I suspect one of the PSU voltages is missing. When I performed PSU resistance checks everything appeared OK. But that's where I'm going to start troubleshooting since there is no vertical and no sweep.

Oh well.....at least there was no smoke. 

Ah great, interesting stuff going on here !

From what you said, looks like it's a solid scope that will be fixed in no time. The fundamentals are all good, CRT and transformer(s) ,  HV stuff.. the rest is the easy stuff... just needs a few hours to troubleshoot it, but sure enough it can be fixed 

So yep, first thing to do is to check all power rails for accuracy and ripple, as always.

Then right after that... before chasing red herrings... I would simply pull all the tubes (yeah, lots of them I know...), and put come contact cleaner into the sockets, and "exercise" the tubes a bit while re-inserting them. I mean, you have already witnessed that simply re-seating the VR tube was enough to bring a power rail back from the dead... so clearly the sockets/tube pins have at least a tiny bit of oxidization, enough to cause malfunction. There is no reason to believe that all the other tubes would not be in the same condition. So check the power rails quickly, takes a minute, then put some music and re-seat all the tubes with some cleaner.

Then give it another test ride, re-evaluate, report back, and start probing around to troubleshoot it... wish I was there with you to do it myself, love fixing these old things !   

Heck, for starters I don't think I'd even pull them - just rock them around in their sockets a bit by moving the exhaust tips in a small circle with a fingertip to exercise the connections - see if that changes anything.

-Pat

<edit - based on post 89339, belay that last thought.>

[Saskia]

well, this was the guy who stole a handgun and practiced shooting in his home to have something in hand in case I wanted revenge for what was done to me during childhood.

Ohhhhkeyyyyy.

anyway. Bloody hell. Don't want to fuck around with the paperwork right now.
Can someone lend me an excavator to take care of the "in the ground" thing ?

[bd139]

Isn’t that a good application for C4? 

[Cubdriver]

When I cleaned the chassis a few weeks ago I did remove all the tubes in that section and sprayed the sockets as well as the tube pins with deoxit. So I was a little surprised that there was a contact issue with that OG3.

Oh, OK ! Great then, you have already done the most tedious part of the job ! 

So you can go ahead right way with the really fun stuff now, troubleshooting the thing. Can't wait...

The VR tube maybe has intermittent internal connections to the pins ?! Don't know if such a thing can happen... but at least if it dies again, you know where to look first !

So, power rails... waiting for the report ! 

Good thought - intermittents at the pin connections at the socket are a possibility - those shunt regulator tubes have internal connections (1-5 for the anode and 2-4-7 for the cathode in the 0G3), the intent being that you feed the angry pixies in on one set of pins and let them out through another - that way if the tube that holds the voltage down is not in the socket (or possibly in this case not making good contact everywhere), the circuit is opened and the unregulated rail disconnected from the downstream circuitry.

-Pat

[Cubdriver]

Isn’t that a good application for C4? 

Flings the dirt around too much - PITA then to collect enough of it again to fill in the resultant hole...

-Pat

[mansaxel]

I do have a gmail address for things that I don't want to give away my personal address for, but the forum has always been associated with my personal address which is a @outlook.com one.

In my opinion an email address is not personal unless one controls the domain name too.  But yeah, I'm not BD139 like that ;-)

[ch_scr]

One 1% 464R resistor was chipped and drifted to 467R.

"drifted" ? At 467 ohms it's still within spec... no need to replace it 

Well unless that chip was indicative of severe overload  rather than just external mechanical mishap ?
You are the judge of that of course... however if only for the value, then no need to replace it, still perfectly good.

Well by chipped I mean: part of the glaze was gone and I could see the metal film element inside, so it had to go anyway.
But you are right, the bugger was still in spec for 1%. Seems like i calculated for 0.1% instead 
In other news after fooling around and convincing myself to change back to the original discrete pair: It still does it with them changed back. Shoot  I can couple more 50Hz into it by touching (both discrete and monolithic) but the root cause is  somwhere else...
 More buggery tomorrow. But on the plus side the monolithic might have a chance after all 

[factory]

Not seen one of these for a while, hp 5240A frequency meter;
https://www.ebay.com/itm/254957334575



David

[xrunner]

anyway. Bloody hell. Don't want to fuck around with the paperwork right now.
Can someone lend me an excavator to take care of the "in the ground" thing ?

Oh my ... 

Only an image that's all I got for you Saskia.