[TechAssist] Re: RCA TV model F32632SB chas. CTC187CN3 HOT runs hot[UPDATE]

  • From: Philip Bader <tjanphyl@xxxxxxxxxxxxxxx>
  • To: techassist@xxxxxxxxxxxxx
  • Date: Sat, 20 Dec 2003 10:18:39 -0500

It seems to me there was an issue on those involving a small 1/8 watt
resistor right under the HOT that went from E to B I think. It would
change value and alter the bias.
Kinda late now, but will check for future ref.
Phil Bader

Gary McCartney wrote:
> 
> Thanks to all the replies about this CTC187CN3 running hot. I have tried
> all the parts suggested (except the flyback) with little or no
> improvement. Because I can't afford any more time, I left the new parts
> in and installed an extra heatsink above the HOT. Now after 9 hours of
> running the set, the temperature is now only 36 deg. C. which is 20 deg.
> cooler than without it. I explained the situation to the customer so
> they know that a fault could reoccur in the future. They use the set in
> the bedroom, so maybe it doesn't run many hours anyways.
> 
> Gary McCartney
> 
> McCartney Electronics
> Guelph Ontario Canada
> Est. 1984
> email: gary (at) number63.ca
> 
> Webster TV wrote:
> >
> > Gary,
> >
> > You've replaced the parts that I usually have luck solving the overheating
> > problem with, but I did have two other parts written down that could cause
> > HOT overheating, so I'll give them to you also. C4303 and C4709.
> >
> >                                           Dan Webster
> >                                           Webster's TV
> >                                           Shullsburg, Wi.
> > ----- Original Message -----
> > From: "Gary McCartney" <gary@xxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Tuesday, December 16, 2003 4:45 PM
> > Subject: [TechAssist] RCA TV model F32632SB chas. CTC187CN3 HOT runs hot
> >
> > > This 32" CTC187CN3 came in with HOT shorted. I replaced with OEM BUH517
> > > and noticed the HOT heatsink was running at 59 deg. C. (approx. 138 F),
> > > measured directly on top of the transistor on the heatsink- which I
> > > believe to be too hot. I remember having a couple of these sets that
> > > were running cooler than that, maybe 45 deg. C.
> > >
> > > I tried another OEM BUH517 - no help
> > >
> > > Also replaced the following:
> > >
> > > -C4306 .047 250V
> > > -hor. driver transformer -with new one
> > > -R4402, 22 ohm
> > > -R4305 4.7K 3W
> > > -CR4402
> > > -CR4403
> > > -CR4106
> > > -C4403 0.55uF
> > > -C4707 .041 400V
> > > -C4409, 47 uF 35V
> > > -C4402 .0157 uF
> > >
> > > I measure 139.2 V dc on cathode of CR4106 (B+)
> > > HOT collector waveform is 1100V p-p no distortion noticed
> > > waveform at base of HOT is 15V p-p and looks ok (manual calls for 12V
> > > p-p but my scope may be acting up a bit)
> > >
> > >
> > > Thanks for any help.
> > >
> > > --
> > >
> > >
> > >
> > >
> > > Gary McCartney
> > >
> > > McCartney Electronics
> > > Guelph Ontario Canada
> > > Est. 1984
> > > email: gary (at) number63.ca
> > >
> > >
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-- 
Philip Bader
Jan Phyl TV Inc. (estab. 1976)
3420 Recker Hwy. Winter Haven, Fl. 33880
Fax (863) 299-8821
email: tjanphyl@xxxxxxxxxxxxxxx

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