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Test Equipment Anonymous (TEA) group therapy thread

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bd139:
Thanks for the link. It's whining again but not arcing now so this is a given that I'm going to rip it all out. I needed a project :)

Apparently the HT transformers on these are usually good so that's a relief. Plan is to get the HT board for the other unit and rebuild it using modern parts then substitute that one in and a new multiplier. Also rebuild the shot one's power supply and stuff that in the good one. Least risk all around then.

Easy to get to all the boards in these unlike some tek equipment! :(

tautech:

--- Quote from: bd139 on May 19, 2018, 10:09:32 pm ---Thanks for the link. It's whining again but not arcing now so this is a given that I'm going to rip it all out. I needed a project :)

--- End quote ---
All the high value resistors in the EHT circuitry had drifted like hell in the D83 I had and the HV ceramics in the DC restorer were sick too. They more than anything else really cleaned up the traces and made them needle sharp.  :)
IIRC some of the HV axial caps were sus too but you probably know all that about these.


--- Quote ---Apparently the HT transformers on these are usually good so that's a relief.
--- End quote ---
Sadly the copied manual I got from the UK had all the measurements handwritten in for the transformer, R's & L's but that copy went with it when I sold it.  :(
The copies online aren't from the same source but the crowd I got it from are still around as I stumbled upon them again just the other day. You'd only need the mainframe manual from them to get those measurements and IIRC it was still the same price I paid yonks ago ~10 quid.
I'll hunt them out if you like .......if I can bloody well remember their name.  :palm:

I think it was Telford:
http://www.telford-electronics.co.uk/index.php

You can probably ask them to check....the transformer measurements were written in/on the schematics for the EHT supply.

bd139:
Yes this has the original caps in it. They are rotten old bits of crap. Flat ceramics, speckled and cracked and film ones which look cracked too. Will be replaced. I've priced a few up and they're not that expensive fortunately. Will order next week once I've checked it over properly. You can apparently get a suitable equivalent multiplier from a company called High Voltage Modules in Braintree here in the UK. I'll give them a call.

Thanks for the link. I've got a spare HT transformer now in the other scope so I might unwind and count it out.

Have just ordered power supply caps. Cost a whopping £5 from RS so far. Embarrassingly small compared to the originals!

mnementh:

--- Quote from: bd139 on May 19, 2018, 10:09:32 pm ---Thanks for the link. It's whining again but not arcing now so this is a given that I'm going to rip it all out. I needed a project :)

Apparently the HT transformers on these are usually good so that's a relief. Plan is to get the HT board for the other unit and rebuild it using modern parts then substitute that one in and a new multiplier. Also rebuild the shot one's power supply and stuff that in the good one. Least risk all around then.

Easy to get to all the boards in these unlike some tek equipment! :(

--- End quote ---

I did that same job on my Tek 2230 a decade ago; then replaced the HV multiplier flyback again this last time I worked on it. Altogether a right crunky affair; I get that the whole mess allowed them to run the beam at lower current, therefore better response and sharper focus at higher frequency... but damn. It's one of those designs that just seems to taunt Murphy.

And worse yet, they "inspired" the designers of your scope to follow in the same ill-advised foosteps...


mnem
Not a fan. Not a grommet, either.

Specmaster:
Essex to the rescue again

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