[TA-A] Re: RCA PTK169PABS(CTC169BT)MOMENTARY 145VOLT STAND-BY VOLTAGE

I've Replaced CR4118 and 4116,all diodes off 
the secondary winding, except 117. CR4402,seems
would only cause a problem if the set is turned 
on.  I'm familirar with common symptoms for the
CTC169 series chassis. This is the standby mode,
I should have a constant 143 volts, but the smps
seems to be working, turns on 3 times, in the 
process the voltage is raised in stages, and then
on the third try it stops providing power. There is
a short somewhere, but I can't seem to find it. The
HV splitter is disconnected and as well asw the
connector to the audio board. The common caps in
the power supply have already been changed since 
they are a common problem. As said before weird 
problem.

Thanks for your input anyway.

--- gs6151@xxxxxxx wrote:

From: "VanNoord TV" <gs6151@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Subject: [TA-A] Re: RCA PTK169PABS(CTC169BT)MOMENTARY 145VOLT STAND-BY VOLTAGE
Date: Mon, 21 Apr 2008 09:45:19 -0400

-check 15v supply - if low CR4118 bad even if checks good
-check for bulging CR4402 or just try a new one
-possible shorted audio out U1900

Gary
VanNoord TV

----- Original Message ----- 
From: " jack spencer" <jackson1@xxxxxxxxxxxx>
To: "freelists.org " <techassist@xxxxxxxxxxxxx>
Sent: Monday, April 21, 2008 8:53 AM
Subject: [TA-A] RCA PTK169PABS(CTC169BT)MOMENTARY 145VOLT STAND-BY VOLTAGE


Dear forum members,
Have a weird problem. When the chassis is plugged in, the main
145 stand-by voltage doesn't maintain this voltage.  It seems
the SMPS is starting and stopping three times and then stops as it
should.  Generally this problem is a short on the secondary side of the
smps, but I can't find any.  The HOT is ok, and with the HV splitter
disconnected I can't get a constant B+ standby voltage, I think
I had disconnected the 145 volt source diode and same problem.

Someone had mentioned replacing the 4 diodes on  the secondary
side of the smps.  The vertical IC pin 8 is not shorted either.

Any suggestions,
Thanks




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