Help Needed With Zenith Ceramic Multicaps - Videokarma.org TV - Video

fsjonsey · #1 08-19-2008, 12:12 AM

I've got a Zenith T1816R Bugeye that has a pretty substantial vertical Linearity Issue. I've recapped the entire set, and replaced most of the resistors in the vertical section, but the vertical is still off. The only thing I haven't replaced are the weird three lead Ceramic multicaps in the vertical section, mainly because I haven't been able to find any information on them, and my Sam's folder just lists the part number, but not the values of the individual caps themselves. I was wondering if anyone here had exerience with replacing them, and if so, how they did it.

wa2ise · #2 08-19-2008, 12:53 AM

Those 3 legged discs have resistors as well as capacitors inside. Which probably have drifted severely. I've seen some info on these, but I've forgotten where. Someone in this forum may know more on these.

Phil Nelson · #3 08-19-2008, 02:57 AM

Hey, I have that same TV and it's playing in my new TV room.

http://www.antiqueradio.org/zen28.htm

It was 10 years ago, but I don't believe I replaced any three-legged critters when I recapped it.

In my Predicta schematics, "couplates" -- resistor(s) & capacitor(s) combined in one shell -- are indicated with a dotted line around the individual components.

If you can determine the values for the individual components inside that thing, it's possible to build a replacement on a tiny piece of perfboard, as I did with my Predicta.

http://www.antiqueradio.org/philc12.htm

Very nice TV when working correctly.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

kx250rider · #4 08-19-2008, 11:19 AM

I hate integrated parts!!!!!!!!!!!!!!

Often, the manufacturer's manual won't show what's in there. But as Phil N. said, Sams usually does, with a blowup diagram in a dotted box. Also you can try Rider's but they usually are just reprints of the factory literature. If you've checked Sams and also Rider, then you might have to reverse-engineer it to find out. I'm not an engineer, but some of the others on the board might be able to take a look at the schematic and come up with an educated guess.

You could try some basic engineering by looking at where the package is located in the circuit, and compare it to another TV which uses a similar vertical circuit. It's probably either two matched caps in series, or maybe with a resistor across them. If it's a thin, flat package, I'd say ceramic caps only.

Charles

bgadow · #5 08-19-2008, 01:01 PM

Post the part number that you need-I have a limited selection of NOS circuits, and I bet some others do as well. Not sure how well they might have held up over the years, but maybe worth a try?

fsjonsey · #6 08-20-2008, 12:17 PM

I just checked my Sams, The part is listed as a Vertical Integrator, Zenith Part Number 87-1.
Edit:
Using Search, I Just found this thread: http://www.audiokarma.org/forums/sho...d.php?t=129777

andy · #7 08-20-2008, 04:17 PM

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fsjonsey · #8 08-21-2008, 01:08 AM

Well, I replaced the integrator tonight, and my vertical still shrinks as the set warms up. Where else should I look to correct this? Vert. Linearity is much better though, no more squished heads.

radiotvnut · #9 08-21-2008, 02:06 AM

Get a can of freeze spray and hit each part until a difference is noted and replace the part in question. You could have an out of spec resistor or a resistor that is changing value as it heats up.

Also, change the vertical oscillator and output tubes. It's usually not the tubes that cause vertical problems; but, it's worth a try.