[TechAssist] [Fwd: FIX: RCA PTV P52750WK,CTC169PABF crackel in speakers then shut down. intermittant.]
- From: Phil Bader <philbad@xxxxxxxxxx>
- To: "techassist@xxxxxxxxxxxxx" <techassist@xxxxxxxxxxxxx>
- Date: Fri, 15 Feb 2002 15:34:52 -0500
-------- Original Message --------
Subject: FIX: RCA PTV P52750WK,CTC169PABF crackel in speakers then shut
down. intermittant.
Date: Fri, 15 Feb 2002 15:33:52 -0500
From: Phil Bader <philbad@xxxxxxxxxx>
Organization: Jan Phyl TV Inc. Winter Haven, Fl. Est.1976.vioce/fax
863-299-8821
I ESR'd all electrolytics on main board. Found that most of the SMPS
caps around Reg IC U4101 were marginal
(C4102,242026/C4104,214756/C4108,208002),changed them all. Also a large
lytic cap, C4801 in the pincush ckt (10MFD NP,227053)was visably bulged
on top.Changed it also. Afterwards I still had the low whine thru the
speakers in standby.Just left it plugged in.Finally when the
intermittant crackle thru the speakers was at it's worst,we powered the
set on. SHUT DOWN! Unplugged the audio board,set worked. Replugged in
the sound module and shutdown again. The audio board was doing it.
Ordered and replaced the two audio output IC's on the 10 watt stereo
board, both were TDA2052. This was final fix.No crackle or whine. Maybe
the smps issue stressed the audio board parts, or just double-troubles.
Any theorists out there? Whew! Done!
Phil Bader wrote:
>
> We pulled the electronics box and have it here in shop. It never did
> shut down for us yet.Today I plugged it in to power and before I could
> turn it on,I heard audible crackel from our speakers plugged into the
> EXT audio jacks to test it. Even when not crackling,I put the speaker to
> my ear and can hear a whine.like an oscillation.All this just plugged
> in,not powered up. I assume there is some standby source that is common
> to the sound and main power of the set..Something that could affect shut
> down and sound...
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