[TechAssist] Re: RCA CTC187 larger screen TVs--info

If you want to solve the "heat" problem, use OEM transistors. If you use a
generic, check the e-b resistance. It should be apx 30-50 ohm, warm the
transistor, if it goes over 50 ohms, it won't stay.
Good luck,
Paul W
C&W Electronics
Azle Texas


----- Original Message -----
From: "Hugh at Main TV" <maintv2002@xxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, February 27, 2003 1:28 PM
Subject: [TechAssist] RCA CTC187 larger screen TVs--info


>
> This is a fix we have used on several problem CTC187 sets--problem will
> be--dead set, hor. output shorted original number replaced, put in new
> flyback (RCA), set runs but heatsink gets very hot after 1 hour or
> so--about 185-190 deg with digital sensor unit. Sencor horz. output
> checker HA325 says the circuit is OK.  If let go TV will go out
> again--same problem-shorted h. output transistor!  We did everything  to
> fix problem--nothing helped.  The fix that has worked is to install a
> small 60 X 60 mm computer type fan - 12v at about 125 ma-on the plastic
> board holder near the horz. output transistor.  This blows cool air
> right on the transistor and heatsink--or can set to exhaust hot air
> away. We use a 12V fan and connect to the +12v regulator Q4852.  We used
> rubber shock mounts to install the last fan for quiet operation, and
> drilled air holes in side of case on a 36 in TV near where the fan sits.
> This problem seems to be mainly on 32in and bigger sets of the CTC187
> line.  These fans can be found on E-BAY for as little as $1 to $2 each
> new.  The temp. on the heatsink after the fan is installed drops to
> about 75deg!  No callbacks!  Note: We found that RCA uses 3 fans in
> their new HD 36in TVs, maybe they know something?
> --
> Hugh Thornley
> Main TV
> 636 Main St.
> Longmont, Colorado 80501
> 303-776-6955
> maintv2002@xxxxxxxxxxxx
>
>
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