[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
- From: "teltek2" <teltek2@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 9 Dec 2002 17:43:57 -0500
Hollis;
A little suggestion....let's leave the "snide" remarks to the AOL chat
groups, not something the rest of us need to hear, so let's move on.
-Ed-
Tel-Tek Electronics
Ontario-Canada
teltek2@xxxxxxxxxxxx
----- Original Message -----
From: <HSWAD@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Monday, December 09, 2002 5:25 PM
Subject: [TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> Wow! In your comments you actually troubleshooted the problem. Now if you
had
> used a scope you would have actually observed what was happening instead
of
> guessing. You can see what those nasty little electrons are doing or not
> doing. I encourage you to use that scope cause you sound like winner to
me.
> You'll love the results. I'll help any way i can even if its by phone-my
> nickel. Hollis Bates, field engineer-retired
> In a
message
> dated 12/9/02 1:53:41 PM Eastern Standard Time, mrfixit@xxxxxxxxxxx
writes:
>
>
> > Subj:[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> > Date:12/9/02 1:53:41 PM Eastern Standard Time
> > From:<A HREF="mailto:mrfixit@xxxxxxxxxxx";>mrfixit@xxxxxxxxxxx</A>
> > Reply-to:<A
HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
> > To:<A
HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
> > Sent from the Internet
> >
> >
> >
> >
> > I completely appreciate the help but I still don't understand how a
scope
> > would have helped here. The fact is the TV was cycling OFF then ON,
> > repeatedly. How could anyone conclude the source of the problem by
> > observing
> > intermittent signals and voltages? The control source for this cyclic
> > action
> > is the micro controller. What would I expect to see on the micro
controller
> > output pin to the relay? A signal level cycling OFF and ON repeatedly.
Not
> > much to conclude here. What else would I look at? The micro controller's
> > oscillator? The oscillator was always running, occasionally with a
glitch.
> > The ON/OFF switch to the micro? Tried that. Power to the micro circuit?
It
> > was intermittent. None of these observation concluded beyond a shadow of
a
> > doubt what the problem was.
> >
> > It was the good old "hunt and peck" method that identified the
intermittent
> > cold solder joint in the micro circuit.
> >
> > I don't have a schematic, but I believe the micro is powered by a
stand-by
> > power source. The cold solder joint repair was in the micro controller's
> > power supply. I'm not sure why I didn't observe more serious oscillator
> > glitches when the problem occured, perhaps the larger electrolytic
filter
> > capacitor kept things running during the power interruption. Just a
> > thought.
> >
> > I trust this concludes all that needs to be said about this problem.
> >
> > Thanks again to all who inputted. You guys are the best!
> >
> > David Lessard
> > Alexandria Electronics
> > Engineering Technologist
> > Embedded Software/Hardware Developer
> > mrfixit@xxxxxxxxxxx
> > (613)525-4502
> >
> >
> > -----Original Message-----
> > From: techassist-bounce@xxxxxxxxxxxxx
> > [mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of HSWAD@xxxxxxx
> > Sent: Monday, December 09, 2002 12:42 PM
> > To: techassist@xxxxxxxxxxxxx
> > Subject: [TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> >
> >
> > Gosh man didn't mean to ruffle your feathers. With your scope you could
> > have
> > observed the action as it turned on and off right back to the source of
the
> > problem. Think about it. would have been faster. Just trying to give you
> > the
> > same idea that I preached for 35 years as a field engineer. Congrats on
> > having a good scope. I remain-Hollis Bates, field Engineer-retired
> > In a
message
> > dated 12/9/02 10:14:54 AM Eastern Standard Time, mrfixit@xxxxxxxxxxx
> > writes:
> >
> >
> > > Subj:[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> > > Date:12/9/02 10:14:54 AM Eastern Standard Time
> > > From:<A HREF="mailto:mrfixit@xxxxxxxxxxx";>mrfixit@xxxxxxxxxxx</A>
> > >
Reply-to:HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx
> > > To:<A
HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
> > > Sent from the Internet
> > >
> > >
> > >
> > >
> > > Hollis,
> > >
> > > Yes I have a scope, a nice one too! And as a professional just how is
one
> > > supposed to monitor a problem where there is a constant cycling of the
> > > power
> > > OFF and ON. I ask you this question. Did you even read the symptom?
> > Anyway
> > > tne problem is resolved, if you have any comments or suggestions in
how
> > > someone should go about troubleshooting an intermittent like this then
> > feel
> > > free to spread the word.
> > >
> > > "Share what you know, learn what you don't"
> > >
> > > David Lessard
> > > Alexandria Electronics
> > > 50 Harrison Street
> > > Alexandria, Ontario
> > > (613)525-4502
> > > mrfixit@xxxxxxxxxxx
> > >
> > > -----Original Message-----
> > > From: techassist-bounce@xxxxxxxxxxxxx
> > > [mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of HSWAD@xxxxxxx
> > > Sent: Monday, December 09, 2002 8:32 AM
> > > To: techassist@xxxxxxxxxxxxx
> > > Subject: [TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> > >
> > >
> > > But you still found it with the hunt and peck method which costs both
you
> > > and
> > > your customer money. Using your scope would have narrowed that down to
15
> > > minutes or so while the trouble was in progress. I have been telling
guys
> > > for
> > > years to be a Tech not a tinkerer. Hollis Bates, Field Engineer
retired
> > > USE
> > > YOUR SCOPE
> > > In
> > > a message dated 12/9/02 6:00:01 AM Eastern Standard Time,
> > > mrfixit@xxxxxxxxxxx
> > > writes:
> > >
> > >
> > > > Subj:[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> > > > Date:12/9/02 6:00:01 AM Eastern Standard Time
> > > > From:<A HREF="mailto:mrfixit@xxxxxxxxxxx";>mrfixit@xxxxxxxxxxx</A>
> > > > Reply-to:HREF="mailto:techassist@xxxxxxxxxxxxx";>
> > techassist@xxxxxxxxxxxxx
> > > > To:HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx
> > > > Sent from the Internet
> > > >
> > > >
> > > >
> > > >
> > > > Symptom:
> > > >
> > > > Cyclic OFF/ON problem (relay clicking) usually after power-up but
also
> > > > occured intermittently. The cycle can be stopped by holding the
power
> > > > button
> > > > ON during the next OFF/ON cycle, then the TV shuts off normally. The
> > > > problem
> > > > was intermittent, sometimes days between acting up.
> > > >
> > > > Solution:
> > > >
> > > > Found numerous postings regarding CR4118, replaced it. No change.
> > > Confirmed
> > > > switch was not the problem by replacing it with another one. No
change.
> > > > Re-soldered in and around HOT area, transformers, etc. No change.
> > Further
> > > > investigation revealed several cold solder joints near R118U - 33ohm
> > > power
> > > > resistor near CR4118. Visual inpection didn't reveal this problem,
the
> > > > joints appeared OK. The problem was discovered by applying pressure
to
> > > the
> > > > PCB near R118U. This dog is out the door.
> > > >
> > > > Thanks to all who provided input.
> > > >
> > > > David Lessard
> > > > Alexandria Electronics
> > > > 50 Harrison Street
> > > > Alexandria, Ontario
> > > > (613)525-4502
> > > > mrfixit@xxxxxxxxxxx
> > > >
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