RCA 8" portable KCS-100 screwed! - Videokarma.org TV - Video

kx250rider · #1 11-20-2005, 01:26 PM

Well now I've seen it all! I picked up this little RCA 8" portable with KCS-100D a month or 2 ago, and finally got around to fooling with it. I noticed that it had a wrong aftermarket back-of-set antenna installed. Those sets normally are close to working, so I opened it up and prepared to variac it. But I noticed a lot of white corrosion when I took out the top Left screw that was holding the antenna on. The pictures tell all..... Now we've all at one time in TV repair careers driven a screw through a PC board, but this takes the cake!

I removed the can from the circuit but left it in place, and installed tubulars to replace it. Works now, but still has the usual slightly out-of-tune horizontal oscillator. (Breaks up and motorboats just before locking in). I remember a tuning capacitor across the oscillator transformer causing that in RCAs, but this one is a different circuit with 2 separate coils. Any ideas?? No Sams in hand.

And NO, I wasn't the one who put that antenna on there

Charles

***Eric H*** · #2 11-20-2005, 01:59 PM

Wow, that mistake was probably made 40+ years ago!
It may have worked for awhile, till the cap dried out.

Chad Hauris · #3 11-20-2005, 05:42 PM

Did you replace all caps? We worked on one of these that wouldn't lock in horizontally on its initial testing with the old caps and we found a paper cap that was thermally intermittent...replacing all those caps did the trick.

I guess the screw sealed up the leak in the electrolytic and it initially did not deteriorate too much!

*Bill Cahill* · #4 11-20-2005, 09:48 PM

That set uses alot of paper caps.It also uses a selenium rectifier which will need replacing. It will need an entire re-build. Don't look for it to bea a great player. It isn't. It is in sam's.

Chad Hauris · #5 11-20-2005, 11:15 PM

I think the performance is actually pretty good once old caps and rectifiers are replaced especially considering the few tubes it uses...it seemed to pick up the local stations well with just the rabbit ears. It uses some tubes in unusual ways such as a 6U8 as an audio output tube but does have a fully isolated power transformer circuit.

kx250rider · #6 11-21-2005, 12:49 AM

Chad, Bill, and Eric, Thanks for the input... I agree on re-capping it being the best, but I hate to put that much time into it. I might end up doing that though. I'll borrow a Sams when I get a chance, and will start re-capping at the junction of the horizontal output and work backwards through the oscillator. I never use these sets much, so if it comes on and shows a picture for a few minutes that will do. I have completely re-capped and aligned one of my Kaye-Halberts, and that one is the one I use if I feel like watching an old movie. But my biggest re-cap job (AND NEVER AGAIN!!!!!!!!) was an RCA 741PCS 41-tube projection set. I did all that, and watched Johnny Carson's final broadcast on it and I can't remember ever using it again. Gary Miller bought it from me a few years later, and I think he used it once too... But using any electronic or mechanical device too infrequently is BAD too. I have picked up several 50s vintage TVs that had been in weekly or monthly use, and all worked great without recapping. But on the other hand, I have a new-in-box Panasonic CT-101 color 1.5" pocket tube set that has all kinds of cap-related problems due to nonuse :deadhorse .

I frown on seleniums too, but these seem OK. Nice full raster. If I jump them, that might boost the B+ enough to speed up the ruin of any original caps... Just a theory but it's like doing a valve job on a 250,000 mile engine without rebuilding the bottom end I suppose.

This KCS-100D does seem quite simple and with very few tubes, so I won't expect it to perform like a big DuMont... The thing that I like about this one is that I have seen dozens of red ones, white, black, and gray and this one is a strange bluish hammertone gray. (Original paint). Never seen one this color before. Saw one dark green one once too.

Charles

***Eric H*** · #7 11-21-2005, 01:08 AM

Dark green wasn't an original color on these, must've been painted.

Red, White, Black & Gray are all there are asfaik.
Saw an ad somewhere that they wern't actually painted either but some type of plastic coating related to bakelite.

kx250rider · #8 11-21-2005, 01:37 AM

This one (bluish gray hammertone) seems original... Not the battleship gray that I have also seen several of. Has all tags with no overspray, and unpainted plastic handle is matching. Could be a custom repaint that was done when it was new. The green one was 20 years ago, so I can't be sure about that one. My impression was that it was original, but no cash bets. I have seen many customized TVs that were done by professionals for interior design contractors, no expense spared. I saw a Mitsubishi front-mirror projection TV (c. 1982) that had been completely disassembled, and covered in pigskin. Even the gas springs for the front mirror door had been disassembled, powdercoated pink cylinders and gold-plated formerly chrome pistons, reassembled and recharged!!!!!! Pink rubber AC cord, and a red LED channel readout replaced the factory green. Then the TV was sent back to the factory in Orange County to be realigned and authorized for new warranty. The owner paid $1000s above the price of the TV for the job. That green RCA could have similar background... It struck me as original when I saw it, but as I say it is a 20-year old memory.

Charles

***Eric H*** · #9 11-21-2005, 03:13 AM

Charles, yours is the correct color grey (or gray?) they all have the slightly rough texture.

I found the picture of the ad that explains the coating, it's a little hard to read though, I grabbed it off eBay a while back.

compucat · #10 11-21-2005, 07:58 AM

I have one of these sets in pristine cosmetic condition inside and out. It did need a full recap which takes a while since you have to diassemble the entire set practically to do it right. Once completed, these sets work rather well. I use mine occasionally to keep it going. It is in the "never to be sold" part of my collection.

Sandy G · #11 11-21-2005, 10:05 AM

KCS-100D ? Looks suspiciously like my 8-PT something er other...I have 3 of them little jewels, 2 blacks, & one that's sorta brownish-grey. I fell in love w/'em back in the early '70s, the dean of students at McCallie had a black one w/tripod in his office. He played it every so often, I thought it was kewl as all get out...-Sandy G

Don Lindsly · #12 11-21-2005, 01:17 PM

That TV uses the RCA synchroguide horiz circuit with two two coils. One is the customer accessible horizontal hold control. The other is a service adjustment designated L108 on the RCA schematic. A quick adjustment would be to get the horiz as close as possible and adjust L108 to fix the "motorboating". Then re-adjust the hold control for lock in. It will only take a 1/2 turn in either direction to fix it.

There is a detailed horizontal alignment procedure using a scope if you are a purist, but if you adjust L108 for max 3 bars top left to lower right before motorboating, it will come out the same.

If trouble persists, the 330 uuf grid coupling should be replaced with a new silver mica.

Don

compucat · #13 11-21-2005, 07:03 PM

After I didi the recap, I set mine up by eye as I don't have a scope. The horizontal coils udjusted easily and I never have to readjust the horizontal hold or the vertical for that matter. The synchronization is very stable. The only real complaint I have about this set is that if the signal is weak, the contrast goes way down. I think it must have only one or two video IFs. I am really spoiled by my 1960s 12" Zenith B&W which has three IFs. It's amazing what a difference 10 years makes in technology.

As vinatge TVs go, this is a good model to own. It is rugged, small which makes it easy to store and display and has that definite Fifties look. I only wish they had built-in UHF.

When digital takes over, I'll just hook it to a converter box and it won't matter that there is no UHF. I just hope the converter boxes available when analog stops have an RF output for the old sets otherwise I'll have to use a modulator like I do now for DVD.

***Eric H*** · #14 11-21-2005, 08:54 PM

They are amazing for sure!
Every one I have worked at least to the point of having a raster, usually the horizontal is whacked.
They really are pretty easy to work on because the chassis unfolds after you remove the side rails.
One complaint, the yoke covers all seem to have deteriorated and the centering rings wont work right.

Chad Hauris · #15 11-21-2005, 11:32 PM

Quote:

Originally Posted by Kaye-Halbert TV

Chad, Bill, and Eric, Thanks for the input... I agree on re-capping it being the best, but I hate to put that much time into it. I might end up doing that though.

If you want it to WORK you have to replace all caps. I take a firm stand on this! We don't mess around with this equipment, we get it on the bench once and replace all caps and seleniums. We have re-capped tube equipment such as jukeboxes and PA amps that are working continuously more than 8 hours a day without fail.

If you just do some caps you will be back into it time and again to fix problems as the caps continue to degrade. This set is especially sensitive to thermal cap problems as the heat builds up more inside the small cabinet.