zenith 7s363 - Videokarma.org TV - Video

sampson159 · #1 06-09-2009, 08:05 PM

hello to all.i have a zenith 7s363.this set worked for about a year now.changed a couple of caps to get the hum out and used sparingly.nice tone and volume.i stripped and refinished cabinet.it looks very good!i turned it on today and the trranformer began to burn.i quickly unplugged.flipped the chassis over to have a look.all was well.checked the tubes and let it cool down.later turned on and it played with good volume for a short time-approx.30 seconds.then the transformer began to burn again.where do i start guys?thanks!

jeyurkon · #2 06-10-2009, 12:10 AM

If you haven't replaced the paper caps, they're almost certainly bad but may not be the problem.

Hopefully you don't have a shorted field coil.

My bet is on the 6X5 even though it might test good. If it has a heater to cathode short or leakage it could cause the symptoms you have. Depending on your tube tester it might not show up.

John

sampson159 · #3 06-11-2009, 04:30 PM

thanks for response.i will check that 6x5.also,i will completely recap this one as i am keeping it.are there any other tubes to sub for this one?i have a few spares but not sure of sub capabilities.don t want to do more damage.those transformers give off a foul odor
when they smoke!

leadlike · #4 06-12-2009, 12:07 AM

I've had a 6X5 fail-luckily it was during an initial power up so I was able to shut down before the transformer failed. My radio worked for about a minute, until I heard an awful hum get louder and louder until I lost my audio. No smoke-but the rectifier filament had suddenly gotten awful bright! The best sub is to use a 6x5g or gt, as they were built a little sturdier. You'll need to recap, of course, and now that you've had an overheating condition, I would REALLY test every component associated with the power supply, to make sure nothing got too toasty. I guess you should dim bulb test the transformer before doing all of that, though-just to make sure the transformer isn't dead.

Tom Bavis · #5 06-12-2009, 08:50 AM

If you're lucky the transformer didn't short from the overload... pull the 6X5 and plug it in with a 100W bulb in series - if it lights the transformer is toast. Use a 6X5GT with the "X" type plates - they're the later versions. I have only seen one of the early "G" type 6X5s... and it was shorted H-K.

marty59 · #6 06-13-2009, 11:47 AM

The early 6X5G's are notorious for shorting and taking out transformers..plus the added danger of the original electrolytics. Zenith made plenty of sets using that tube.

As mentioned, the newer production 6X5 is the way to go. It's nice to have original era tubes on these Zeniths with the exception of the rectifier!
I've got a 10S567 and a 8S463 that suffered bad transformers so be cautious when bringing your set back up!

As for those tubes, there's plenty of them out there including the ruggedized version 6X5WGT's. Sylvania seems most common and the Raytheon is a short/stubby envelope style.