[TechAssist] Re: RCA F35751MB CTC169BG5 pop in audio, orig had shorted HOT

  • From: "Larry E" <videotech@xxxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Thu, 7 Jul 2005 17:23:33 -0400

Update;  replaced the following bad caps on the audio module
C560, C568, C901 & C902 and have re-installed Q915 but set
still pops once now at start-up or shutdown, any ideas?  tia, Larry E
Larry Eastman
American TV & Electronics
Crystal River, Fl. 34428
----- Original Message -----
From: "Larry E" <videotech@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, July 07, 2005 4:00 PM
Subject: [TechAssist] RCA F35751MB CTC169BG5 pop in audio, orig had shorted
HOT


> Hi Guys, picked up this monster F35751MB because it had a shorted HOT,
replaced with oem
> checked all the diodes and caps in Horizontal circuit, standby B+`s were
all good so I started
> it up, made loud popping sounds through speakers and would not run, pulled
P1903 from
> audio board and set started with good picture, replaced both audio
outputs, this chassis uses
> 2 tda2052`s, replaced 2 low profile electrolytics that were leaking fluid,
C905p & C564p ,
> re-installed P1903 set still is very hard to start and pops loudly, have
both + & - 17
> volt supplies but found that the 5 volts on smd transistor Q915`s
collector is dropping with
> the pop cycle, removed this DC sense transistor and set will pop once and
start perfectly
> with good audio, it also pops once when shutting off the set, l checked
the smd transistor it reads
> good, I don`t have the exact schematic for this audio stage but it appears
this 5v collector line
> for Q915 comes from the main module, anybody got any tips for this problem
? Thanks in advance
> Larry E
>
> Larry Eastman
> American TV & Electronics
> Crystal River, Fl. 34428
>
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