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#1
02-17-2026, 08:49 AM
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RCA 630TS-KCS20 sync-sound issue
This set belongs to another Vk'er who lives fairly close to me. For the payment of a Philco 21" color set, I was able to get the chassis carefully restored, yet it took 2 years of on and off attention.
After a full recap and replacement of selected resistors, I have a 95% working set on first power up. The HV and both H and V Sweep look good on my 5" test CRT. Using a STB (AntennaManPa box) and OTA signal, sound and video seem to land on same channel and as the circuit implies, contrast behaves like an AGC control. Its the sync that is absent for both horiz and vertical. I also noticed the sound is weak and somewhat distorted. >Voltages all close to spec on sound IF, det and output. Volts on grid of 6K6 output -20, should be -9. Bridged 93 ohm resistor to reduce bias, dropped it to -10 but still mushy sound. I suspect these issues are connected so, let review the work I did in video stages. The set plays for an hour several nights and no new issues have shown up. Any ideas are welcome and if solved, I will certainly post the solution here but Im stuck. 630TS.jpg
__________________
"When resistors increase in value, they're worthless" -Dave G 
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#2
02-18-2026, 04:37 PM
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Can't see the image you posted.
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#3
02-27-2026, 10:22 AM
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630 TS.jpg
Quote:
I have isolated the problem to the horizontal AFC and reactance stage. I have the RCA service book that explains how the pre-synchro guide horizontal stage works. This really makes you appreciate the 6CG7 H-osc versions of later 50s!
__________________
"When resistors increase in value, they're worthless" -Dave G
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