[TechAssist] [Fwd: saga continues: callback!Re: partial fix,update:Re: update Re: Gateway Vivitron 21 (fcc# BGBTHN9105K)smoked,dead,was off-H.freq intermittantly]]]
- From: Phil Bader <philbad@xxxxxxxxxx>
- To: "techassist@xxxxxxxxxxxxx" <techassist@xxxxxxxxxxxxx>
- Date: Tue, 13 Nov 2001 18:01:38 -0500
-------- Original Message --------
Subject: saga continues: callback!Re: partial fix,update:Re: update Re:
Gateway Vivitron 21 (fcc# BGBTHN9105K)smoked,dead,was off-H.freq
intermittantly]]
Date: Tue, 13 Nov 2001 17:59:26 -0500
From: Phil Bader <philbad@xxxxxxxxxx>
Organization: Jan Phyl TV Inc. Winter Haven, Fl. Estab. 1976
To: Electronic Hardware Repair <ELREPAIR-L@xxxxxxxxxxxxxxxxxxxx>
References: <3BF05715.CCB91250@xxxxxxxxxx>
Ran two days solid OK here. Customer picks up, has 4 hours,finds he has
a virus,is repeatedly rebooting PC, Monitor shows off-frequency display
at one certain boot up,then dead. Put on bench again today: the 11 volt
zener I replaced was OK,but my HOT and FET shorted again. I'm
depressed.Don't know if it was anything customer did,or what...If
there's a GOD, I need advice...
Phil Bader wrote:
>
> Tear down again! Found the daughter board (OSD)I removed to access the
> FET and surrounding parts in orig. repair. Remove and reseated. Width
> trouble cured.
>
> -------- Original Message --------
> Subject: [Fwd: partial fix, update:Re: update Re: Gateway Vivitron 21
> (fcc# BGBTHN9105K) smoked,dead,was off-H.freq intermittantly]
> Date: Sat, 10 Nov 2001 11:34:12 -0500
> From: Phil Bader <philbad@xxxxxxxxxx>
> Organization: Jan Phyl TV Inc. Winter Haven, Fl. Estab. 1976
> To: "techassist@xxxxxxxxxxxxx" <techassist@xxxxxxxxxxxxx>
>
> -------- Original Message --------
> Subject: partial fix, update:Re: update Re: Gateway Vivitron 21 (fcc#
> BGBTHN9105K) smoked,dead,was off-H.freq intermittantly
> Date: Sat, 10 Nov 2001 09:15:32 -0500
> From: Phil Bader <philbad@xxxxxxxxxx>
> Organization: Jan Phyl TV Inc. Winter Haven, Fl. Estab. 1976
> To: Phil Bader <philbad@xxxxxxxxxx>
> References: <3BD6FC1E.34112ACF@xxxxxxxxxx>
> <3BD86BC5.3A4623DA@xxxxxxxxxx>
>
> Replaced shorted 11 volt zener D528, FET Q521 (2SJ307) and HOT Q506
> (C5244A). Seemed OK on test generator. Today I entered menu,tried to
> increase H. Width more. The OSD goes from 0-100 but no change.( a very
> slight linearity change) Its a bit narrow by an inch or so both sides.
> It's not the inch, it is the fact I cannot change the H. width,
> indicating still a problem. No schemo...PLease help. TIA, Phil.
>
> Phil Bader wrote:
> >
> > Here's what I have found: The short in the HOT collector line was due to
> > a shorted zener diode D528 (A-11 on body)Unsolder zener,short gone. D528
> > is in the source lead of shorted FET Q521 (J307). So, I know I have a
> > shorted Q506 HOT (C5244A),shorted Zener D528,shorted FET Q506 (J307).
> > Don't know what else.Don't find any other shorts. I need to find the
> > value of the zener diode,and if the HOT C5244A has a suitable sub.I
> > think B&D has it @ $20.00! I assume the FET is a 2SJ307. Thanks for any
> > input.
> >
> > Phil Bader wrote:
> > >
> > > This was an intermittant problem for a long time. Would go off freq on
> > > 800x600 ( probably all modes,but this was his "working" res.)sometimes
> > > work all day.Customer said last night it smoked and went out totally. I
> > > see no heated areas top or bottom,or source of smoke/burnt areas. I do
> > > have a shorted HOT Q506. Unsoldering Q506 collector lead I still get a
> > > short on the collector trace on board (HOT is also bad). I think I have
> > > a shorted FET Q521 at the middle of board. A row of FET's near HOT are
> > > all OK (Q517,518,519,520)No scan caps seem shorted. Lytics are not
> > > bulged,tho I havn't ESR'd them yet (Many).This is a bear to get into. Is
> > > there any info on these bad parts or the orig. instability that must
> > > have lead to this? TIA, Phil
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