[TechAssist] Re: Sony CTV KV27EXR20 (Chassis ANU-2) H. O. T. Shorts after 20 Minutes.

Oh god!  No SK's....that IS your problem!

Not sure on the sub...just stay away from SK outputs and vertical amp IC's

==========================
Jeff Stielau
Shoreline Electronics Repair
344 East Main Street
Clinton,CT 06413
860-399-1861
860-664-3535 (fax)
jstielau@xxxxxxxx
==========================
"If you push something hard enough it will fall over."
Fudd's First Law of Opposition - Sir Sidney Fudd


----- Original Message -----
From: <HarrisTV50010@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Saturday, May 31, 2003 5:43 PM
Subject: [TechAssist] Sony CTV KV27EXR20 (Chassis ANU-2) H. O. T. Shorts
after 20 Minutes.


> I have a Sony Model KV27EXR20 Chassis ANU-2. The first time this set was
in
> the shop it had a bad STRS6301 Regulator IC but the H. O. T. Was Ok. I
checked
> and resoldered any questionable connections. The customer had the unit
home
> about 2-weeks and it died again.
> This time the 2SD1886 H. O. T. had shorted. I checked the horizontal
circuit
> using our Sencore TVA62 and everything checked ok. I replaced the H. O. T.
and
> it ran for 20 minutes and shorted again.
>
> This time I thoroughly rechecked the regulator circuit using a resistor
load
> and everything checked perfectly. I thoroughly went over the chassis for
any
> questionable connections. I resoldered everything is the base drive &
collector
> circuits of the H. O. T. I replaced the 2SD1886 again. I monitored the
base
> drive and the collector waveform using our X100 scope probe. Everything
looked
> textbook perfect. The Collector pulse width was 14us, which is normal. I
did
> start monitoring the temperature of the H. O. T. Using an Infrared
Thermometer.
> The temperature started rising and the transistor shorted at about 165
> degrees.
>
> Does anyone have any ideas what might be causing problems? I am using RCA
SK
> 2SD1886 which I haven't had any problems in the past. I checked
RepairWorld
> and someone had used a 2SC4729 as a replacement. Do I need to try an exact
Sony
> replacement? Any thought would be greatly appreciated.
>
> TIA,
> Dale
>
> Dale A. Lubow... HarrisTV50010@xxxxxxx ..515-232-1109..(Fax)515-232-3356
> Harris TV & Appliance..........335 Lincoln
> Way.....Ames.....Iowa.....50010-3384
>
>
>
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