TOUGH DOG: RCA TV model 27V412T, chassis M134C turns off, then on by itself
 

Hi,

The problem is back after around 4 days. It started when I turned on the
TV, a moment later the TV turned off. Then it turned on by itself, then off,
etc. I had to pull the plug.

Thanks in advance, Brad


On Thu, 08 Nov 2007 12:36:44 GMT, in sci.electronics.repair you wrote:

Hi,

I removed the "Power" button switch from the front panel circuit board.
Note: I had checked the switch for leakage using a capacitor tester
and 50V, but there is no "leakage". There is no sign of anything
out of the ordinary on this very clean pcb. There is no residue from a
spill.

Since I removed the "power" button switch, the problem went away,
but for how long? I will post an "UPDATE" a couple weeks from
now if the problem doesn't come back. If the problem does come back,
I will post another reply to this thread.

Brad


On Mon, 05 Nov 2007 16:18:35 GMT, in sci.electronics.repair you wrote:

Hi,

PLEASE READ my original post below.

I have a RCA TV model 27V412T, chassis M134C (mfg 01/06) back in my shop,
which I thought I repaired after I replace the remote receiver. The TV worked
fine for a couple days, then it started all over again. I removed the remote
receiver and put a 10K from +5 to the remote's output line, but the TV
still turns on, then off by itself. I checked for leakage on the panel button
switches. Also I found out, before I removed the remote receiver, the TV
would not respond to remote commands, and the scope showed a good
output signal from the remote receiver. Note: The TV did respond to remote
commands when I first started working on it. I checked the +5V and scoped it
for noise.

I found info on the Web about a setting in the service menu that can cause
this problem, via "7", OPTM2 should be at "00", but this setting is correct
("00").

Did you have a similar problem with this or similar a model TV?

Thanks in advance, Brad

On Thu, 25 Oct 2007 14:25:39 GMT, in sci.electronics.repair you wrote:

Hi,

I have a RCA TV model 27V412T, chassis M134C (mfg 01/06) in my shop
that seems to have a mind of it's own. My customer said this problem got
worse over time (a few weeks). I have Sams Photofact 5234.

The TV will play for a short time, then turn off, a short time later, it
turns back on, then again it goes off, etc. I checked all solder joints
(AOK).

HV is 28KV, reg B+ is 130V "run", and 10V in standby.. While the TV
played, flexing the circuit board (removed from it's holder), tapping the
circuit board, using a hot air gun on parts, had no effect.

I checked electroylitics in primary side of SMPS and reg. B+ (AOK).
I checked voltages on secondary side of SMPS and found a schematic
error for 24V source. I found 24V present at emitter of Q205 used as a
"switch" (one of several) which indicates the 24V source is normal.

Did anyone encounter a similar problem?

Thanks in advance, Brad

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