Test Equipment Anonymous (TEA) group therapy thread

[bd139]

I knew that was coming 

[Brumby]

Wouldn't want to disappoint you.   



Do you have success?

[bd139]

Not sure yet. Had to take a break to do some work 

[med6753]

Standing by with 911 on speed dial and potential words of condolences. 

[Mr. Scram]

Standing by with 911 on speed dial and potential words of condolences. 

"Bd139 was a brave man, but unfortunately born with penisfingers. His condition has lead to the demise of many a machine and ultimately his own. We wet our tips in silence."

[Specmaster]

It's the verticals. I've done them before a couple of times

Decided feck it and will do it.

Once you started, there was never a chance that you'd not do it today, you got the bug now.

Sent from my POT-LX1 using Tapatalk

Will watch for a puff of smoke coming from the East. 

That would be a mushroom cloud then [emoji23]

Sent from my POT-LX1 using Tapatalk

[Specmaster]

Standing by with 911 on speed dial and potential words of condolences. 

"Bd139 was a brave man, but unfortunately born with penisfingers. His condition has lead to the demise of many a machine and ultimately his own. We wet our tips in silence."

With it looking like a bombs gone off at bd's I guess that I missed the cloud then.

Sent from my POT-LX1 using Tapatalk

[bd139]

Not dead, no explosions.



Not celebrating yet. There appears to be a couple more problems: wont trigger on channel 1 (looks like switch issue as it does on norm), trace "zoom" changes slightly occasionally (reckon thats HT supply feedback), horizontal pot is bust (one on the 465 is good so I'll steal that). For another day.

So this nifty 200MHz scope cost £5 and the multiplier and missing case parts I had in my parts mule 465 in the cupboard.

Best bit: the attenuators work properly 

Honestly I think this was wonky out of the factory. Looking at the insides there's no crud in it at all and no soot under the HT shield so it hasn't had much "up time". Going to leave it running for 2-3 hours and see if it's just got some damp in it as there's evidence of damp storage on the frame.

[med6753]

Good deal, progress!  And having good attenuators is definitely a plus. 

[Specmaster]

Not dead, no explosions.



Not celebrating yet. There appears to be a couple more problems: wont trigger on channel 1 (looks like switch issue as it does on norm), trace "zoom" changes slightly occasionally (reckon thats HT supply feedback), horizontal pot is bust (one on the 465 is good so I'll steal that). For another day.

So this nifty 200MHz scope cost £5 and the multiplier and missing case parts I had in my parts mule 465 in the cupboard.

Best bit: the attenuators work properly 

Honestly I think this was wonky out of the factory. Looking at the insides there's no crud in it at all and no soot under the HT shield so it hasn't had much "up time". Going to leave it running for 2-3 hours and see if it's just got some damp in it as there's evidence of damp storage on the frame.

If its not been used much, might it be oxidized contacts? Good work so far though, might be worth that fiver after all then?

Sent from my POT-LX1 using Tapatalk

[bd139]

not sure it is.

HT just blew up 

Looks like the fuse has gone so this might actually be more taunting tantalum twats.

[Specmaster]

not sure it is.

HT just blew up 

Looks like the fuse has gone so this might actually be more taunting tantalum twats.

Perhaps you need to revise your advice you gave that other person asking about swapping out capacitors. Instead of on demand as they fail, to swapping anything that is approaching 30 years old?. I thought that you did swap them all, especially those bastard tants on Tek scopes anyway?

[tautech]

not sure it is.

HT just blew up 

Looks like the fuse has gone so this might actually be more taunting tantalum twats.

Perhaps you need to revise your advice you gave that other person asking about swapping out capacitors. Instead of on demand as they fail, to swapping anything that is approaching 30 years old?. I thought that you did swap them all, especially those bastard tants on Tek scopes anyway?

Yep, 'specially when you've just been in there ! 
Impatience always bites you on the bum.

[med6753]

Bastard tants! 

[bd139]

Well that was a short lived success but I know a root cause now.

After doing some debugging and pulling the vertical again, I have confirmed that the second multiplier is now dead as well. Not only that but when it went it took the multiplier winding of the HT transformer out too. Turns out this winding is more fragile than the fuse is. Poking around it appears that the HT oscillator feedback resistor from the high voltage side of things (the thick film array one) is shot causing the voltage to shoot up to the overvoltage protection. It has basically been running wedged up there until the multiplier fails. Really I suspect it is a manufacturing flaw that was possible to cal out with the grid bias as there's no sign of use otherwise. Not even any dirt in the fan.

It's dead. RIP. Now 100% BER. So it's now an organ harvesting operation.


Just a quick postscript. I am now officially giving up on restoring old Tektronix scopes. I'm thoroughly done. Many have passed through my hands now and I am not going to do any more. I need a new challenge. Here's the tally though. I think I did good considering everything I bought was broken or for scrap or was supposedly working but wasn't or wasn't shown as working...

Restored (20 scopes)

- 3x 475
- 2x 475A
- 5x 465
- 3x 465B
- 2x 453
- 1x 2235A
- 3x 2225
- 1x 7603

Scrapped (5 scopes)

- 1x 465B
- 1x 465
- 1x 475
- 1x 453
- 1x 2235

I'm not including the 5x Philips, 2x Hameg, 2x HP, 1x Thurlby, 2x LG, 1x Hitachi, 6x Telequipment (3x D83, 2xD61, 1xS61) ones on top of that as well 

Phew  ...

[tautech]

And the Telequipment ones don't even count ? 

[bd139]

LMAO forgot them. Adding now ....

[mnementh]

For you rf-ily folks... BaoFeng-UV-82HP for $45 from US warehouse: My cart sez delivery by July 19. 

I think there's maybe 3 of the black ones left, and over altogether in 2 hours.

https://smile.amazon.com/BaoFeng-UV-82HP-CAMO-Power-Radio/dp/B00Z52HP10

Cheers,

mnem
*lazily grazing the verdant fields of slAmazon Prime Day*

[mnementh]

Just for bd139... 
mnem
There... that's better.

[mnementh]

Still Grazing...

Wiha Insulated Screwdriver set $23 for the next 30 min: https://smile.amazon.com/Wiha-32091-1000-Volt-Insulated-Screwdriver/dp/B000T9UG60/

Also, Torx kit T5-T30 $11: https://smile.amazon.com/Wiha-79242-Piece-Selector-T5-T30/dp/B001US4RMI

and full System4 Bit Kit $27 for the next 5 hours: https://smile.amazon.com/Wiha-75992-Precision-Interchangeable-Phillips/dp/B0000WTBO4/

mnem
moo?

[Specmaster]

Well that was a short lived success but I know a root cause now.

After doing some debugging and pulling the vertical again, I have confirmed that the second multiplier is now dead as well. Not only that but when it went it took the multiplier winding of the HT transformer out too. Turns out this winding is more fragile than the fuse is. Poking around it appears that the HT oscillator feedback resistor from the high voltage side of things (the thick film array one) is shot causing the voltage to shoot up to the overvoltage protection. It has basically been running wedged up there until the multiplier fails. Really I suspect it is a manufacturing flaw that was possible to cal out with the grid bias as there's no sign of use otherwise. Not even any dirt in the fan.

It's dead. RIP. Now 100% BER. So it's now an organ harvesting operation.


Just a quick postscript. I am now officially giving up on restoring old Tektronix scopes. I'm thoroughly done. Many have passed through my hands now and I am not going to do any more. I need a new challenge. Here's the tally though. I think I did good considering everything I bought was broken or for scrap or was supposedly working but wasn't or wasn't shown as working...

Restored (20 scopes)

- 3x 475
- 2x 475A
- 5x 465
- 3x 465B
- 2x 453
- 1x 2235A
- 3x 2225
- 1x 7603

Scrapped (5 scopes)

- 1x 465B
- 1x 465
- 1x 475
- 1x 453
- 1x 2235

I'm not including the 5x Philips, 2x Hameg, 2x HP, 1x Thurlby, 2x LG, 1x Hitachi, 6x Telequipment (3x D83, 2xD61, 1xS61) ones on top of that as well 

Phew  ...

Well that is a very impressive tally over the years, but maybe the older scopes are getting just a bit to old now and its about time they were allowed to die in peace? The 453 lasted from 1965 to 1974 so they could anything from 45 to 54 years old now and at just 10 hours a week over its life, its had an awful amount of stress and things like multipliers are bound to be extremely fragile by now. So then whats your plan now, start looking at scopes from say the late 80's to 90's or is that it, done now for all time?

[BFX]

Welp.... how did this happen? 

Hmm TiN ... I think my addiction level is to low and I should forced it up



May be I will catch you in the next life 

[med6753]

Well I guess I'm now the Lone Ranger for keeping old Tek junk alive since bd is now bowing out.  Currently everything in my Tek tribe is working fine except a 465B that looks like it may have some filter caps in the PSU giving up the ghost. I'll get to it within a few weeks. I got Tonto keeping an eye on it. 

The Heath S-3 rebuild is done. But unfortunately it's got a few problems which really isn't surprising. First, the square wave that the 2 inputs ride on is extremely unstable. It keeps bouncing around. I suspect a cold solder joint somewhere. Should be easy to track down.

The 2nd problem is interesting. See the scope trace. I only have an input going into "A input" (top trace). Nothing on "B input" and it's gain is zero. The bottom trace should have nothing on it...should be flat line. So there's cross talk in the switching circuit which may or may not resolve itself if I fix the unstable "rider" square wave. And yes, I reversed things.....signal on "B input", nothing on "A" and that has the same crosstalk.



 

I get back to this tomorrow.

 

[bd139]

Are you sure that isn't a feature? 

Well that is a very impressive tally over the years, but maybe the older scopes are getting just a bit to old now and its about time they were allowed to die in peace? The 453 lasted from 1965 to 1974 so they could anything from 45 to 54 years old now and at just 10 hours a week over its life, its had an awful amount of stress and things like multipliers are bound to be extremely fragile by now. So then whats your plan now, start looking at scopes from say the late 80's to 90's or is that it, done now for all time?

Completely agree with all points. The statistical rate of failure is too much of an enthusiast thing now to fight and honestly I don't have the time. You either have to go simpler or newer. Thus I'm going to stick with the DS1054Z as my one and only scope now and give up the analogues. Once they fix all the stuff in the MSO5000 and it's readily crackable I'll hit that. The whole journey has been productive for sure and Jim Williams was very much right with the assertion that a broken scope is an effective classroom. I've learned a hell of a lot of design and diagnostic tricks.

As for what's next, I don't know. Perhaps the Tower of Flukes needs to happen but no more scopes at all!

[Mr. Scram]

Completely agree with all points. The statistical rate of failure is too much of an enthusiast thing now to fight and honestly I don't have the time. You either have to go simpler or newer. Thus I'm going to stick with the DS1054Z as my one and only scope now and give up the analogues. Once they fix all the stuff in the MSO5000 and it's readily crackable I'll hit that. The whole journey has been productive for sure and Jim Williams was very much right with the assertion that a broken scope is an effective classroom. I've learned a hell of a lot of design and diagnostic tricks.

As for what's next, I don't know. Perhaps the Tower of Flukes needs to happen but no more scopes at all!

The MSO5000 looks frustratingly slow though.