RCA "Deluxe" Portable KCS-111D

[JSMCMS]

Hi Guys,

I've been struggling on how to fix a horizontal width issue (way two wide) and I stumbled upon a solution but it worries me. I was testing C106 and forgot to re-solder it and all of a sudden, I have good width control via T4. I've not replaced C106 for leakage (I can test up to 450V) but I've substituted an equivalent arrangement of multiple capacitors and with the new arrangement, the problem returns. I've not replaced C106, R106 or C107 but I'm not sure they are the problem. With C106 left in place, the best width I can achieve is about 10-15% overshoot with the T4 slug fully retracted. With C106 out of circuit, I can adjust T4 to a midpoint and achieve a normal width picture.

I've looked through Grob's, Basic Television Principles & Servicing but nothing quite matches the example designs and this RCA. Has anyone run into this issue? How about the purpose of C106? It looks like some kind of boost bypass to one side of the yoke but I'm not sure why. Second question, can you think of any long range issues keeping C106 disconnected?

Thanks in advance, Scott

[old_coot88]

Originally Posted by JSMCMS

Second question, can you think of any long range issues keeping C106 disconnected?

No harm leaving it out if that gives you the width range you're looking for.

[Notimetolooz]

I think that C106 may form a resonance with the flyback winding. That could make sense that it would effect the width. May effect the boost voltage and HV also. Is there a chance that the flyback was replaced? Did you confirm the original value of the cap? SAMS has been know to make mistakes.