[tvservice] Re: New Post--Fuse keeps blowing; Dead TV
- From: "Steeve" <starfury_@xxxxxxxxxxx>
- To: <tvservice@xxxxxxxxxxxxx>
- Date: Mon, 26 Apr 2004 20:09:42 -0400
You got a bad FBT...the reading you get is normal...when the transistor is
in circuit, the collector-emitter reading you have is the primary winding of
your FBT...and because your ohmeter measures ohms by send DC volts, you`re
measuring the electrical resistance of the primary winding(not the
impedance). Replace the FBT (if it is affordable)and everything should be
okay...also check the HV capacitor between the collector and emitter of your
H.O.T for open or short.
P.S. The outer leads on a H.O.T are always from left to right
Base-Collector-Emitter. Sometimes, there`s a 30-50ohm resistor between the
base and the emitter inside the transistor casing, and sometimes, you may
measure a damper diode in reverse polarity between collector and emitter.
Regards
Steeve Cavanagh
----- Original Message -----
From: "Mike Selnick" <selnick@xxxxxxxxxxx>
To: <tvservice@xxxxxxxxxxxxx>
Sent: Monday, April 26, 2004 7:56 PM
Subject: [tvservice] Re: New Post--Fuse keeps blowing; Dead TV
> Looked like a nice call at first. I disabled B+, gave it a new fuse,
> plugged into 120vac, and the fuse did not blow. The horizontal output
> transistor emitter and collector outer leads both seemed to be shorted to
> ground on the ohmmeter. After I removed the transistor, I did some
ohmmeter
> checks on it: Emitter to collector reads 7k ohms, emitter to base reads
5k
> ohms, and base to collector reads infinity. (Reverse ohmmeter polarity
> gives infinity for the same three readings.)
>
> Do you still think it's a bad transistor or that other faults are
grounding
> the emitter and collector?
>
> ----Original Message Follows----
> From: "graytv" <graytv@xxxxxxx>
> Reply-To: tvservice@xxxxxxxxxxxxx
> To: <tvservice@xxxxxxxxxxxxx>
> Subject: [tvservice] Re: New Post--Fuse keeps blowing; Dead TV
> Date: Mon, 26 Apr 2004 10:06:25 -0400
>
> First thing I would do is disable the B+ to the flyback and sacrifice
> another fuse.
>
> If it doesn't blow then check the horizontal output transistor for a
short.
> If it's ok then you might have a bac flyback.
>
> If the fuse still blows, then check the secondaries for shorts.
>
> BTW, a good check to see if the primary side is ok, after disconnecting
the
> B+, is to check pin 1 of U4101 for -40v to hot ground. If that is good
then
> the regulator circuit is almost certainly (never say never), working
> properly.
>
> hth, Russ Gray, A+, Pres.
> Gray's Electronics Inc.
> 201-C Commonwealth Blvd.
> Port Orange FL USA 32127
> 386-322-0904 voice
> 386-322-3809 fax
> graytv@xxxxxxx email
>
>
> ----- Original Message -----
> From: "Mike Selnick" <selnick@xxxxxxxxxxx>
> To: <tvservice@xxxxxxxxxxxxx>
> Sent: Saturday, April 24, 2004 5:25 PM
> Subject: [tvservice] Re: New Post--Fuse keeps blowing; Dead TV
>
>
> > Thanks, Russ. Hello List members. My first time aboard. It's been
> decades since I did TV repair work.
> >
> > I'm working on a 31-inch RCA GE 31GT659, Code 45104, Chassis CTC 186/7
> > bought from Sears in Feb. 1996. Set is completely dead. Fuse f4001 is
> > open.
> >
> > I replaced the 5A. fuse and 2.3-ohm 15-watt power resister r4001 and
> plugged the power cord into 120VAC power. Even *before* I had a chance to
> turn
> the set ON, the Fuse immediately opened and f4001 resister was very hot to
> the touch. A good on-line troubleshooter recommended (for similar model
RCA
> GE set) that ic U4101 (STK730-010) is probably shorted and should be
> replaced.
> > I did quick ohmmeter checks of all the diodes and resistors in the
power
> supply and they look ok.
> >
> > Question: What jumps out as the most likely faulty component to replace
> and how would you test it beforehand? ( B+ filter? Degauss relay k4201
or
> thermistor rt4201, Switch Mode xformer T4101, Hybrid Switch Mode Reg U4101
> ic, Closed caption filterQ3302?)
> >
> >
> > ----Original Message Follows----
> > From: "Hoyt's TV" <hoytstv@xxxxxxxxxxx>
> > Reply-To: tvservice@xxxxxxxxxxxxx
> > To: <tvservice@xxxxxxxxxxxxx>
> > Subject: [tvservice] Re: New Post
> > Date: Sat, 24 Apr 2004 09:36:29 -0400
> >
> > I think you have the honor of making the first post, Mike.
> > I signed up for the list on March 21st and yours is the first I've seen
> from
> > it.
> >
> > Russ Hoyt
> > Hoyt's TV
> > Exeter, NH
>
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