[TechAssist] Re: Mitsubishi WS-65807 eating convergence modules

  • From: "Leonard G. Caillouet" <lcaillo@xxxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Fri, 20 Feb 2004 11:11:11 -0500

Joel,

You might check a couple of things.

First, these sets have been very bad about coolant leaks. Check the boards
thoroughly.  Then check again.  I had one that started with repeat
convergence problems and turned out to be a small spot of coolant on the
board.

I have been told by a tech at Mitsubishi that excessive correction in the
consumer point convergence compared to doing it in the service menu can
cause the chips to run hot.  I thought at first this was BS but had one that
had a chip that got obviously hotter than normal (and they do run pretty
hot).  I couldn't get the convergence quite right so I finally gave up and
started from scratch.  I found that there was a large offset in the h
position and readjusted the yoke, centered the parameters and it turned out
fine.  The chip ran noticeably cooler.  I suspect what happens is there is
too much dc offset on the output sometimes.  Back to basics, I guess.
Hitachi is pretty specific about the offset on their setup, I have been told
for the same reason.

Another situation I had recently was a leaky op amp in a Toshiba DCU that
was causing the output to blow.  Check the DC on the waveforms into the
output ICs and the dc offset on the outputs to the yokes.  It should be
pretty low.

As for the source for the chips, it is not necessary to buy them from
Mitsubishi.  I only do so when the product is under warranty to simplify
getting paid.  Otherwise I use chips from B&D (sometimes) and Tritronics
(TT- generics almost always) all the time.  The only problems that I have
had is that Tritronics bags them without any foam and the pins come in bent
or broken occasionally.  They are 100% about taking them back and issuing
replacements or credit.

Leonard G. Caillouet
Electronics World
Gainesville, FL
352-332-5608
352-332-5668 (fax)

----- Original Message -----
From: "Joel Jacobs" <jjlists@xxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, February 19, 2004 1:41 PM
Subject: [TechAssist] Re: Mitsubishi WS-65807 eating convergence modules


> No, I got them from B&D.  I've never had any problems with part quality
from
> B&D.  However, the first set of IC's that burned up were definitely from
> Mitsubishi...
>
> Joel Jacobs
> Ohio Consumer Electronics
> Pickerington, Ohio
>
> ----- Original Message -----
> From: "John @ Myers TV" <myers_tv@xxxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Thursday, February 19, 2004 1:14 PM
> Subject: [TechAssist] Re: Mitsubishi WS-65807 eating convergence modules
>
>
> > Joel,
> >
> > Are you getting the IC's from Mitsubishi?
> >
> > John Myers
> > Myers TV Service        Since 1984
> > Alliance, OH
> > For Professional Technicians ONLY
> > ph 330-821-6545
> > ----- Original Message -----
> > From: "Ohio Consumer Electronics" <jjlists@xxxxxxxxxxxxxx>
> > To: "Tech Assist" <techassist@xxxxxxxxxxxxx>
> > Sent: Thursday, February 19, 2004 12:58 PM
> > Subject: [TechAssist] Mitsubishi WS-65807 eating convergence modules
> >
> >
> > > Hi folks,
> > > Worked on this BS a year and a half ago - the convergence was
> > intermittent.
> > > I replaced the STK392-570 modules.  While I was removing the old ones
I
> > > found some leads had come loose from the modules and other ones broke
> off
> > > easily if I moved them.  When I got the new ones in I found out why -
> Them
> > > suckers run hot!  If the spec on the modules was 70 deg C. then they
> were
> > > real close.  The picture on the TV was perfect - both geometry and
> > > convergence so I just figured it was designed that way...
> > > Last fall it fails again - this time the STK's short and take out the
> > > supplies too.  When taking the STK's out I noticed loose leads again.
> Got
> > > it working again and as before, perfect picture and the STK's hot as
> ever.
> > > Customer just stopped by the shop and says it's doing it again.  I
> thought
> > > it would at least last through the winter - it was in a cool corner.
> > Anyone
> > > got any thoughts what could be this things problem?  Thanks much!
> > >
> > > Joel Jacobs
> > > Ohio Consumer Electronics
> > > Pickerington, Oh
> > >
> > >
> > >
> > >
> >
>
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