[VCSMaster]

Originally Posted by zeno

Thats a nice clean set !
Anyhows the SAMS will have subs for the transistors on the MAD
& other boards. BTW sometimes the MAD boards are encapsulated.

This one and the replacement I bought look identical. Both bare boards.

All red pix is either G-2 too high or red K too low. Possibly set-up
or CRT also. A few measurements point the way.

I plan on doing a setup (or at least tune-up) once I get the new MAD001 installed. That way, I have all 3 colors and can do a proper convergence and balancing.

Tuner number starts with KRK### Start with a good cleaning.
Pull the cover & just put cleaner on the contacts. We used to use
WD40 then douche it out with freon then lube it. RCA tuners often completely
quit when dirty.
The symptom of good UHF snow / bad VHF snow usually the VHF oscillator
if cleaning doesn't help.

When the tuner was out, I wasn't able to find any labels or markings on the VHF section of the tuner. Just the UHF section. Would they be the same?

Like I said, I cleaned them both the same way I clean AM and FM radio tuners. It's electronic contact cleaner. Should I be using WD40 instead?

ALL VHF positions (2-13) produce quiet static on audio and a completely red screen.
The UHF positions (14-83) produce much louder static and visible red and blue snow on a black background.

When my LCG-388 pattern generator is attached, some of the channels produce a picture, albeit oftentimes in poor quality. It broadcasts on channel 6 and the set picks it up on several UHF channels between 20 and 67. Absolutely no change on any of the VHF channels.

When my Samsung Medalist VCR is attached and set to broadcast on channel 3, the set picks up the audio on both channel 2 and 3. The audio is noticeably more clear on channel 2. Fine tuning does not affect this. When set to broadcast on channel 4, the set does not pick up the audio at all. None of the other VHF channels produce audio or a picture, and none of the UHF channels produce anything more than static or at best a few flickering lines that never adjust into anything.

I have a working oscilloscope, but it's not great for measuring exact frequencies and tops out around 10MHz. Would this be enough to check the VHF oscillator or do I need something else?

A word about RCA part numbers.
1) six digit part number. Almost never on the part but the final number.
2) assembly numbers. 3 letters then 3 numbers. Like MAD001 etc.
3) drawing number. Often on the parts. long number ends in -###
Most of the time SAMS has everything.

These MAD001 units have several different numbers on them, I searched all of them before coming across NOS boxed units on eBay for a decent price.

I've bought a Sam's folder for the set on eBay, but it won't be here for a week or two yet. Just trying to get a decent-ish picture on the screen for now.

Since analog television is all but dead, I've been contemplating bypassing the tuner and just adding a composite input to the set. Any idea of the difficulty of this?



Oh, and the green came back very weak for just a moment. As soon as I tried to adjust the level it went black again. It really seems like the transistor is going open.