On Sat, 11 Dec 2004 23:22:28 -0330, "Rono" wrote:

M # F19431, ch # TX 809D, dead, nothing
blown, voltages throughout, no info, $ 3.00+/Min
to talk to RCA techs! Any ideas? Rono.


Welcome to new chassis weird design. This SMPS is burst mode during
stand by. It is controlled by the freq of SMPS via micro. (!!).
Anyway, two items that can keep it from going correctly even you do
have voltages:

One small electrolytic cap in the feedback circuit in hot side, SMPS
was outputting too low volts and was sagging with varying loads. Use
ESR meter. Bad electro cap was blue one.

There is a two diodes side to side (cold side) that feeds the
regulator for the standby power, not that one that is fed by SMPS
transformer, that two diode is farther from SMPS outputs, near cutout
PCB toward front. I had too low standby power because of this diode.
RCA use this diode in series. I don't know why they need that diode.

Watch for shorted diode & cap in parallel in horizontal circuit. Bad
or cracked solder joints applies.

Cheers,

Wizard