[TechAssist] Re: CTC 187 power supply update
- From: "Webster TV" <webstertv@xxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 27 Feb 2002 09:53:18 -0600
Bill,
Try replacing, R4402 in base circuit of HOT, replace even if checks
OK.Found this tip in a Euras diagnostics manual for RCA, and it solved the
problem of the HOT shorting in a set I was working on.
Dan Webster
Webster's TV
Shullsburg, Wi
----- Original Message -----
From: Bill S <billans@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, February 26, 2002 7:12 PM
Subject: [TechAssist] Re: CTC 187 power supply update
>
> Hi again;
> getting weirder, Pin 11 and 12 of U4101 is running at 156 volts like it
> calls for. However the voltage is not on the collector of the Horizontal
> output and because of not the usual symptons that occur when the HOT is
> shorted, I did not check it. *BIG MISTAKE* It is shorted.
> What actually was happening that inside the U4101 regulator is a
overcurrent
> sensor and when the current that is needed to keep the 156 volt line on
pin
> 11&12 exceeds a *over current* value then the bottom half of the regulator
> will not run which will not produce the standby voltages that are needed
to
> 'start' the set.
> I then replaced the Horizontal output and ran the set for a little bit and
> then started putting the set back together when it went out. The HOT
> shorted again.
> Any ideas on this??
> Bill Sorensen
> New Life Video & Audio
> billans@xxxxxxxxxxxx
> - - - - - - - - - - - - - - - - - - -
>
> ----- Original Message -----
> From: "Bill S" <billans@xxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Tuesday, February 26, 2002 2:59 PM
> Subject: CTC 187 power supply
>
>
> > Hi all
> > This unit came in a couple of days ago dead. I checked the U4101
> > (STK730-150) and on pin 1 & 2 were -1.4 volts, pin 4 had a +1.5 volts on
> it.
> > I assumed that the regulator was bad and ordered a new one. I put the
new
> > regulator in and still the set will not start up. There is the raw 160
> > volts B +. The schematic shows that this supply should start running
when
> > plugged in and that the standby voltages should be up at least. Nothing
> is
> > going on.
> > This is going to be one of those dumb things I have overlooked. Right?
> > What did I miss?
> > Bill Sorensen
> > New Life Video & Audio
> > billans@xxxxxxxxxxxx
> > - - - - - - - - - - - - - - - - - - -
> >
> >
>
>
>
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