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

  • From: "Webster TV" <webstertv@xxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Tue, 16 Dec 2003 19:23:04 -0600

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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