[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
- From: HSWAD@xxxxxxx
- To: techassist@xxxxxxxxxxxxx
- Date: Mon, 9 Dec 2002 18:34:33 EST
Stop it fellows! I am trying to impart some help here. I actually would use
my phone to help anyone solve a technical problem. Hollis Bates,fireld
engineer-retired In a message dated 12/9/02 5:44:28 PM Eastern
Standard Time, teltek2@xxxxxxxxxxxx writes:
> Subj:[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
> Date:12/9/02 5:44:28 PM Eastern Standard Time
> From:<A HREF="mailto:teltek2@xxxxxxxxxxxx";>teltek2@xxxxxxxxxxxx</A>
> Reply-to:<A
> HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
> To:<A HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx</A>
> Sent from the Internet
>
>
>
>
> 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:HREF="mailto:techassist@xxxxxxxxxxxxx";>
> techassist@xxxxxxxxxxxxx
> > > To:HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx
> > > 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:HREF="mailto:techassist@xxxxxxxxxxxxx";>techassist@xxxxxxxxxxxxx
> > > > 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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