Author Topic: DOA Zenith......  (Read 113 times)

addyboy

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DOA Zenith......
« on: August 29, 2017, 03:52:32 PM »
Hi all,
I recently acquired a very nice 26NT20 console which was doa. First thing was check the fuse which was blown. Got the chassis out and did a detailed inspection and found the cause of the fuse blow...a pilot lamp lead had came into contact with the AC mains coming in.....isolated that wire but there is no DC at all.
The pilot lamp feed was coming directly out of the transformer......do you think that momentary burst of AC on a positive DC lead of the transformer fried it before the fuse blew?

TC Chris

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Re: DOA Zenith......
« Reply #1 on: August 29, 2017, 09:42:51 PM »
Get out the voltmeter and see what's coming out of the transformer.  Wasn't Zenith known for marginal power transformers anyway?  Even if it's fried it's not the end of the world--look for a suitable donor unit (it's why I never overlook a beat-up old chassis with a transformer on it).

Chris Campbell

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Re: DOA Zenith......
« Reply #2 on: September 01, 2017, 11:26:23 AM »
See if you have DC resistance of a few ohms across the primary. Since this is not a tube set, a 6.3 volt pilot light winding has very little current capacity, that winding has one lead to chassis ground, and if in contact with AC mains, may have had paths available back to AC. The schematic is in the "downloads" section of this site. But I would be surprised if it affected the primary.

I have the same receiver chassis in a 1966 TV-stereo combo. If you find the primary open, I have a transformer in a 1969 junk chassis. 
Tubes - Magical - Tubes

Dave