[TechAssist] Re: [Fwd: Proscan PS27151 (RCA,CTC169CE2)dead no shorts]

  • From: "Damon" <damon101@xxxxxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Wed, 19 Sep 2001 16:26:47 -0500

Q4101 has no voltage on base?? And q4101 isn't shorted....I think there's a
47uf or a 39uf cap from pin 14 to the base of q4101....wish I had my
schematics in front of me here...that cap has been known to get leaky and
kill the smps output transistor Q4101. Monitor the B+ voltage starting with
the TV unplugged....What happens to the B+ when you plug it in. Do you see
it rise up to 140-145 volts and stay there or does it rise up, then slowly
drop to 0 volts. Does it go past 145 volts, then die??

If it goes past 145 volts there is a 2.2uf cap by u4101 that controls the
standby's regulation voltage.
----- Original Message -----
From: "Phil Bader" <philbad@xxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, September 19, 2001 1:49 PM
Subject: [TechAssist] [Fwd: Proscan PS27151 (RCA,CTC169CE2)dead no shorts]


>
>
>
> -------- Original Message --------
> Subject: Proscan PS27151 (RCA,CTC169CE2)dead no shorts
> Date: Wed, 19 Sep 2001 14:48:26 -0400
> From: Phil Bader <philbad@xxxxxxxxxx>
> Organization: Jan Phyl TV Inc. Winter Haven, Fl.  Estab. 1976
> To: "CONSUMERELREPAIR-L@xxxxxxxxxxxxxxxxxxxx"
> <CONSUMERELREPAIR-L@xxxxxxxxxxxxxxxxxxxx>
>
> No squeel in stby,HOT OK, all diodes around HOT OK,Fuses OK.U4101 SMPS
> IC has most all voltages except pin 14 (to base of Reg Q4101) which is
> zero. I changed U4101 and Q4101 as test. Plug in and I hear a very faint
> tic,tic,tic(exactly three).Still dead and no response with remote or
> power button.Changed the 'lytics around the U4101 area.The 2 watt
> resistors nearby all OK. Has Vcc on U4101. Zero volts on HOT collector
> in stby.CR4118 OK. U 4101 seems to have what it needs,just
> unresponsive.On one U4101 pin my fluke shows the analog bar in the
> digital display as pulsating up and down at 1 sec rate.Changed D4118 as
> test. (I'm stumped).-Phil
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