[TechAssist] Fwd: Sharp 55R-WP4H one more try FIX
- From: Paul <dntwntv@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 22 Oct 2004 11:51:12 -0700 (PDT)
I have been struggling with this set for a very long time on&off. Finally after
practically rebuilding the convergence circuit. I decided to replace the amps
again, I/C STK 392-040. I had used generic I/C's originally and because the
symptom was the same I assumed that was not the problem. I didn't use sharp
I/C's because they are about $43.00 apiece. I put Panasonic I/C's in for about
$28.00 apiece. If that didn,t fix it I wasn't going to put any more time and
money into a losing repair. They did fix the problem. I read a post just
recently about bad convergence I/Cs, I think It was by Bob Waterman, but don't
know if they were OEM's or not. At any rate It got me to thinking along the
right path. Thanks again Bob you are a major asset to this list. Yes I could
have put gold plated I/C's in and come out better than I did. Don't know if
it's stubbornness , frugality, or stupidity. Maybe a little of all three.
Paul
Paul <dntwntv@xxxxxxxxxxxxx> wrote:
Date: Fri, 10 Sep 2004 17:26:20 -0700 (PDT)
From: Paul
Subject: Sharp 55R-WP4H one more try
To: techassist@xxxxxxxxxxxxx
I posted this problem several weeks ago but no one was familiar with it.
Thought I would try one more time. This set will not allow the SMPS to operate
unless I disconnect any one of about 5 different plugs. They all seem to be
related to the convergence circuit in some way. The strange thing is that if I
unplug a yoke plug for instance or open the -25v supply to the convergence
amps, then plug the ac in it will operate and the set will run for as long as
you want. Unplug the ac for more than two or three minutes and then plug it
back in the SMPS will not run. The indicator light flashes three on one off.
Supposed to indicate an under or over voltage in a number of secondary
supplies, one being -25 volts. Have replaced both convergence amps both supply
diodes (that measured bad but were not) that was another discussion. Have
checked all ( 4 ) 2200mfd lytics in the -25,+25 v line. The only apparent
abnormality in the -25,+25v line, is that they are both a bit high, 32v, when
running
+39v &- 40v in standby, but the - 25v line is the only one that needs to be
opened before plugging in the ac,or unplugging any of the plugs on the
convergence driver board. Have been over that board a dozen times checking all
the components beside the amps that were replaced. Why does it run at all ?
Been on this along time. Have reached the end of the rope.
Paul
Paul ,B
Central TV&Video
911W Grand Ave
Grover Beach Ca.
(805)481-8084
Paul ,B
Central TV&Video
911W Grand Ave
Grover Beach Ca.
(805)481-8084
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