Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Dec Sun 15, 2019 3:33 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 22 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Tektronix Type 545 A Oscilloscope CRT Replacement
PostPosted: Nov Sun 17, 2019 7:33 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5414
Location: Sunbury, Ohio 43074
The black coating is most likely high voltage "corona dope". (old trade name) for what is basically a paint on high voltage insulation. It may still be available, or perhaps you can scrounge up an old bottle from a restorer of old TV's. Without actually looking at the circuit, I'd imagine the points that were so coated were at the higher high voltage potentials, and this would have prevented arcing even if the terminal strips got dusty/dirty or otherwise.

As far as replacing the caps, it might seem like a good idea, although if your other repairs fix the problem it might be best just to leave them alone. I'm in the "if it's working don't fix it" camp with these kinds of instruments. They appear to be 400V caps, so you could test them the usual way if you have a cap tester that provides these working voltages. The Sprague TO series, Heathkit IT-11 or 28, etc. all can test a capacitor under it's stated working DC volgage, up to I believe 600V.

If an oil cap is not actually leaking oil, it may be just fine. Not assured, however.

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: Tektronix Type 545 A Oscilloscope CRT Replacement
PostPosted: Nov Sun 17, 2019 8:58 pm 
Member

Joined: Mar Thu 29, 2012 8:51 pm
Posts: 265
Location: upper midwest
I made some comments and added photos in this thread that maybe of use in working on the HV in your 545A.

viewtopic.php?f=8&t=339646&hilit=tektronix+531&start=0

Those HV rectifier tubes would not be expected to glow during the timed warmup as they get their filament power from 1 turn wrapped on the HV transformer core. Said transformer is in the 60khz (if I recall correctly) oscillator so it won't be oscillating until they relay clicks and the B+ supplies all come up.


Top
 Profile  
 
Post New Topic Post Reply  [ 22 posts ]  Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: Google [Bot] and 7 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB