RCA 21-D-7479 restoration progress

[mbates14]

FINALLY after more than a year or so, i am able to get around to restoring this beast. chassis KCS104H.

ok before restoring, the set would power on wiht audio, no HV.

blown damper. this verified the Tuner, IF stages, and sound stages were operational. along with its power supply.

i recapped the entire set, powered it on, same thing. i found the blown 270v scan supply fuse, and i replaced the 150ohm R110 that was blown open at some point in the past, it feeds the 270v source to the screen of the vertical output.

after erplacing the damper, and doing that, the set FINALLY came on with HV. although it had no raster, and about 30 seconds after the HV came up, that r110 blew open again, and popped the 270v source fuse again.

I still got the electrolytics to go, so this all may change when i replace all the lytics. but i dont think the lytics are responsible for blowing R110, as it has nothing to do with the lytics. it just feeds supply to the screen of the vert output. but when the HV was running, normally you can hear pulses in the vertical output transformer, i heard nothing.

any ideas?

[mbates14]

recapped lytics, same problem.


the yoke is bad. both horiz windings are open, and one of the vertical windings are open.

WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAaaa

anyone got a yoke?

According to sams, the yoke part number its:

Merit: MDF-92 and in circles: 5 6 7

Thordarson: Y-41-1 circles: 5 6 7

RCA: 101147 8

[wa2ise]

Sometimes coils like yokes and IF transformers in old radios go open right at the solder terminal. Because of crossive rosin. If that's what happened, you might be able to restore the yoke. This is a long shot, though...

[mbates14]

no i tried this.

i had an old 16" air king yoke i kept around. i wired it in the circuit, guess what, picture!!! although the linarity is way off, and the horizontal is bunched up every quarter way in the picture, but i have raster, i have TV!

but i need the yoke. as the picture is screwed up with this one. (assuming the horiz resonance doesnt match this yoke)

[Tubejunke]

I have a bunch of Merit and Thordarson yoke and flys that I have posted for sale but I did not see the #'s you mentioned. Sorry...

By the way I am going to have to move the parts CHEAP due to job loss. Also test equipment and probably some old radios will be up for grabs but not as cheap as the flys and yokes.

[bgadow]

Check with the good old standby, Moyers Electronics. You will need to call or email them as the old stock parts are not on their website. www.moyerelectronics.com, as I recall.

I will check my inventory when I get home. I really should print out a second copy and keep at work. I only have a few NOS yokes, though.