KCS201 - schematic needed/dead tuner

[probnot]

Anyone know where I can find a schematic or service doc for a KCS201 chassis (TV model CX095E)? This is one of those retro-style mid 1970s 9" black and white sets.

As far as I can tell the RF stage in the tuner is dead. When I got it, the VHF tuner was dead (on channels 3 and 4), but UHF was showing the OTA digital noise so it appeared to be working.

Once I brought it inside to test UHF, it worked at first, but as I tuned to a station it would "disappear" after a few seconds. Now it appears both bands are not tuning. I can however modulate a signal on channel 2 and pick it up slightly off frequency, though fine tuning doesn't work. I think this may be because channel 2 is close to the IF frequency (I don't have any equipment that can directly inject an IF signal).

Anyone have any thoughts on where to start on this? I have no doubt this will need some recapping, but I want to get the tuner working before I blindly start replacing stuff.

[damen]

I couldn't find any CX models, but did find AX

[probnot]

Originally Posted by damen

I couldn't find any CX models, but did find AX

I think this will work, thank you!

I wonder if CX may have just been the Canadian version.

[zeno]

1) sometimes RCA VHF tuners get so dirty they quit.
2) Check the UHF IF cable. They open especially if just crimped.
3) be sure UHF is getting B+. Prob 12 VDC.
4) In the UHF there are U shaped grounds along the rotor.
Put a few drops of WD40 on them & run back & forth.
You can pull, clean & bend them but thats risky.

You can put IF in to the UHF IF input to test the VHF tuner on UHF.
If you dont have an analyst you can make a tuner subber out of a scrap tuner.
BTW on RCA the tuners have a number KRK###. thats the part number.
they also had a six digit p#.

73 Zeno
LFOD !

[probnot]

I finally got around to working on this TV again, and wanted to thank you guys for the help!

I was able to get the UHF tuner back up and running - it was just incredibly dirty and a quick spray of contact cleaner on the 3 tuning caps (and the required wait time for it to fully evaporate) fixed it right up!

VHF on the other hand is still broken. VHF low channels will show a signal off-tune, with the fine tuning not doing anything (I verified the fine tuning is physically turning the slugs). VHF high is stone dead. I gave the tuner a full cleaning, but no improvement. Voltages look correct (if I recall I saw 18vdc on VHF, 12vdc on UHF). I'm thinking it's the oscillator not running but I'm not knowledgeable on this to go further, nor do I want to dry and remove any tiny parts from the tuner!

At this point I'm happy since the TV channels I modulate in my house are all UHF anyway.

[zeno]

Sounds like the osc is out.
When turned to UHF the osc gets turned off & the RF and mixer
get turned into 2 more IF stages. SO most likely they are OK.
Changing the osc is full of risk so leave well enuf alone IMHO.

73 Zeno