[TechAssist] Panasonic CTV # CTK-2790S, Chassis# AEDP152 or GL7C Repeat IC801 failure
- From: HarrisTV50010@xxxxxxx
- To: techassist@xxxxxxxxxxxxx
- Date: Tue, 17 Sep 2002 18:31:17 EDT
We have a Panasonic CTV Model# CTK-2790S Chassis# AEDP152 or GL7C. This unit
came in with the complaint of popped and went dead. We found C821, IC801 &
D805 shorted. Q801 has a hole blown out of it and R826 was open.
We replaced C821, IC801, D805, Q801, R826, C807 & R825. After replacing these
parts the set worked for a couple of minutes with all the proper voltages
coming out of it. Then it suddenly went dead. We found IC801 had gone bad
again. We replaced it, shorted the power relay and slowly brought up the AC
going into the set. The B+ coming out of the secondary of the switching
transformer T801 are normal. The IC starts to get hot. The waveform on the
collector (pin 3 ) of IC 801 seems normal except the frequency seems to
quiver too much and the base (pin 2) of IC801 is supposed to be 14v p-p but
we only get about 4v p-p with the same frequency quivering as the collector.
We have checked every other part on the primary of the power supply and
everything seems OK. Sorry for writing a novel about this unit. Does any one
have any notes on possible problems with this power supply?
TIA,
Dale
Dale A. Lubow... HarrisTV50010@xxxxxxx ..515-232-1109..(Fax)515-232-3356
Harris TV & Appliance..........335 Lincoln
Way.....Ames.....Iowa.....50010-3384
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