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3T77A manual and mildew issue


 

Does anyone know where I can download a copy of a 3T77A (not 3T77) manual?

Also, any idea as to what could cause this kind of mold/mildew on only the axial electrolytic caps, and no other components? Storage humidity? The other components all look like new except for that weird white speckling on every one of the caps (and the deteriorated paper jacket on the large cap)...

I tried to include a pic but got an error that the group does not accept attachments.

thanks

Charles


-
 

The OLD paper bodied caps were often coated in bee's wax. That might be
the culprit.

On Mon, Feb 8, 2021 at 12:36 PM Charles <charlesmorris800@centurytel.net>
wrote:

Does anyone know where I can download a copy of a 3T77A (not 3T77) manual?

Also, any idea as to what could cause this kind of mold/mildew on only
the axial electrolytic caps, and no other components? Storage humidity?
The other components all look like new except for that weird white
speckling on every one of the caps (and the deteriorated paper jacket on
the large cap)...

I tried to include a pic but got an error that the group does not accept
attachments.

thanks

Charles







unclebanjoman
 

Hi Charles,
I own both 3t77 and 3t77a, in perfectly working state.
I have the original 3t77 manual but never I found the 3t77a manual.
However there is a copy of the 3t77 manual with added 12 pages of manual change information regarding the 3T77A version that explain very well the differences and the adjustment procedures. There are the schematic changes also.
You can find it here: http://bama.edebris.com/download/tek/3t77/3t77.djvu
It is in djvu format, not as usual as pdf, but easily readable for example, with IrfanView

Max


 

Turns out the 3T77A change information (which is considerable) is part of the online 3T77 manual. So I'm good there.

The white specks on the outside of the capacitor sleeves wipe off with alcohol and swabbing, but the ink has migrated into the plastic sleeve so I can't read values. The only one that looks like it should definitely be replaced is the large 250 uF power supply filter cap (the red rubber seal has what looks like a burned spot pushed from the inside). More as I have time to play with it!