[TechAssist] [Fwd: RCA P56812BL (PTK195AP) projo.shut down,fixed then no main video, PIP OK: FIX]
- From: Phil Bader <philbad@xxxxxxxxxx>
- To: "techassist@xxxxxxxxxxxxx" <techassist@xxxxxxxxxxxxx>
- Date: Wed, 14 Nov 2001 11:33:01 -0500
-------- Original Message --------
Subject: RCA P56812BL (PTK195AP) projo.shut down,fixed then no main
video, PIP OK: FIX
Date: Wed, 14 Nov 2001 11:31:00 -0500
From: Phil Bader <philbad@xxxxxxxxxx>
Organization: Jan Phyl TV Inc. Winter Haven, Fl. Estab. 1976
To: "CONSUMERELREPAIR-L@xxxxxxxxxxxxxxxxxxxx"
<CONSUMERELREPAIR-L@xxxxxxxxxxxxxxxxxxxx>
First, In home noticed at turn on,developed high voltage,then shut down
in about 10 seconds.Took the chassis into shop.Disconnected input wire
of high voltage splitter block assy,and still unit would shut
down,indicating a possibly bad block was not at fault.Since no vertical
deflection will do this,I found two test points for vert:( printed on
the chassis board) Scoped TP14501 which is vertical output drive
waveform . Instead of a good ramp waveform,I got a low level "trash"
signal.Replaced vert. output IC U14601 (TDA8172/ECG1788) No help. I then
scoped the vert.scan drive output from the T chip pin at TP14502. Still
nothing. Ordered and replaced the "T" chip U16201 (LA7612N, RCA 241266).
This restored the HV and cured the shut down.Now, no main picture
video,only the PIP window has video,and have OSD.Same thing at line
inputs as well as tuner.Has sound. RCA tech assist said trouble was one
of two chips: Video switch U26901 (TEA6415C, RCA# 235447, $10.00) or the
PIP chip U10100, 235448 @ $46.15). Replaced the switch IC, then the PIP
IC still same.Finally got the microfische, in ten minutes found the loss
of video between emitter of SMD Q18100 vid. buffer and coil L18108. ONly
thing between was the badly cracked SMD resistor R18132 (220 ohm). This
R18132 was final fix. Wrapped it up with the recommended tuner upgrade
procedure ( bulletin TV 98-001).Out Da Door! Whew! ;-)
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