56" RCA CTC185

[Karen Ray-Stewart]

Can anyone help with this problem,

Checked out this 56" set it had blown a 5 amp fuse so I replaced the fuse.
Now the set works fine, but the convergence is all screwed up, where should
I look to find the problem......is it in the convergence board ?? or the
main board ??
What voltages should I check for ???

I have serviced tv's for over 10 years, not overly familiar with rear
projection and the convergence circuitry. I have a good idea how it
functions, though.

Thanks
James

 

[John Hutchison]

Change Reg on Con board plus maybe other parts.

kip

 

[Art]

Power supply circuit specific to the Convergence circuit. As stated,
regulator ic plus check other active components for leakage.

 

[Phil Bowser]

First I believe you may have a PTK195, not a CTC185, since CTC185s
were only used in low-end 22-25? 27? inch models...

Assuming I am correct about the chassis number, look to the convergence
power supply board bolted to the top right (viewed from the rear). This
board is available as a complete unit for under $75 (I think), but I usually
repair them... On the ones that actually manage to blow the main fuse in
the set, you'll probably find a shorted diode or diodes in the secondary.
Look for the large ones that supply the +15 and -15V to the convergence
board below. I believe the P/N is 243636, but doublecheck me... When this
/ these diodes short, it will almost always also cause the main regulator IC
(Big one bolted to the heatsink) to fail as well, which blows the main fuse.
In some cases, when the fuse is replaced, this IC then OPENS, which will
allow the set to run without re-blowing the fuse, albeit without any
convergence correction in the picture due to no supply voltages...

So, replace the IC, and the diodes and I bet it will work for you...
Hope this helps...and the good news for you is that once you repair the
supply, you probably won't even have to readjust any convergence alignments,
assuming it looked o.k. before the diode shorted and caused the supply to
fail.