[TechAssist] Re: GE 20GT425 Turns OFF/ON Repeatedly
- From: "David Lessard" <mrfixit@xxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 9 Dec 2002 17:45:21 -0500
Wow! Your sarcasm is unbelievable, old dogs like you will never change, and
I mean that in the most respectful way. I did use my scope but it didn't
reveal much except the oscillator glitch. Yeah, this may have been a clue to
what was going on, but I missed it, this only affirms that I am human. We
learn from our mistakes, and when you learn the hard way you never forget!
I appreciate and respect your advise, I hope to remain a "winner" with you
Hollis. Season Greetings to you and yours. Cheers.
"Share what you know, Learn what you don't"
David Lessard
Engineering Technologist
Embedded Software/Hardware Developer
mrfixit@xxxxxxxxxxx
(513)525-4502
-----Original Message-----
From: techassist-bounce@xxxxxxxxxxxxx
[mailto:techassist-bounce@xxxxxxxxxxxxx]On Behalf Of HSWAD@xxxxxxx
Sent: Monday, December 09, 2002 5:26 PM
To: techassist@xxxxxxxxxxxxx
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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