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

I recently repaired two CTC187 32" sets. One I used an OEM RCA HOT. The
other set I used a generic BUH517.  The OEM measured 47 deg. C on the
heatsink directly above the transistor and the generic BUH517 measured
48 deg. C. These measurements were both taken after 2 hours of
operation. The generic had the exact same "look" to it as the OEM. I
have since ordered another generic and it has a "different" look to it.
Perhaps this one is counterfeit, I don't know but I will try it next
time and measure the temperature. I just measured the resistance with my
Fluke 77 meter. Using the Ohms scale, I get 1.6 meg from B to E and
infinety the other direction. On diode test, it measures like any proper
NPN bi-polar transistor. This transistor does not measure like it has
internal resistors. Does this mean it is a definite counterfeit?




Gary McCartney

McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: gary (at) number63.ca







C&W Electronics wrote:
> 
> 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
> >
> >
> ****************************************************************************
> *
> > Submit A Repair Tip Here, or Change/Remove your Email Address:
> >         http://www.tech-assist.org/secure/tip/main.html
> >
> ****************************************************************************
> *
> > For automatic password retrieval 24 hours a day, go to:
> > http://www.tech-assist.org  and select "Lost your Login Info?".
> >
> ****************************************************************************
> *
> >
> *****************************************************************************
> Submit A Repair Tip Here, or Change/Remove your Email Address:
>         http://www.tech-assist.org/secure/tip/main.html
> *****************************************************************************
> For automatic password retrieval 24 hours a day, go to:
> http://www.tech-assist.org  and select "Lost your Login Info?".
> *****************************************************************************

-- 




Gary McCartney

McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: gary (at) number63.ca

*****************************************************************************
Submit A Repair Tip Here, or Change/Remove your Email Address:
        http://www.tech-assist.org/secure/tip/main.html
*****************************************************************************
For automatic password retrieval 24 hours a day, go to:
http://www.tech-assist.org  and select "Lost your Login Info?".
*****************************************************************************

Other related posts: