[TechAssist] Re: Mitsubishi V6015R Proj TV (correction)
- From: Paul <dntwntv@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Mon, 16 Feb 2004 12:20:11 -0800 (PST)
Thanks a lot Leonard. I don't do as many as you by any means. That is quite a
routine. To bad that the board is not replaceable. I have not checked all the
caps yet, only the ones that seemed to pertain. Will go back and see what I
have missed. Paul
Leonard Caillouet <lcaillo@xxxxxxxxxxxx> wrote:V10 chassis. Capacitors.
We have found that on the Mitsubishi V10, V11, and V12 chassis and related
variants it is pointless to service the sets without carefully going over
the electrolytic capacitors on all of the major boards. We typically find
at least 2 dozen leaky or high ESR capacitors on the V10 and V12 sets and at
least 60 on the V11 (my record is 146).
Similarly on the direct view chassis WA, UM2 and RA variants expect a couple
of dozen bad caps.
Most of the leaky caps are Rubycon and Nichicon polar electroytics with
black labels. Earlier Mitsubishi chassis rarely have many leaky caps, more
likely normally aged ones like you would expect in any set. Later chassis
may have a few leaky caps in the power supply and audio circuits and PIP
modules, but not to the extent of these.
Our procedure goes like this:
0) Test the CRTs. If they are bad or have any scored phosphors, NWR.
Prepare the customer for a big repair bill.
1) Look for spots around caps.
2) Look for black on the negative legs.
3) Look for black on the traces at the negative legs, as well as gray
powdery looking solder.
4) Resolder the caps that do not visually indicate electrolyte leakage,
listen and smell. Leaky caps will often sizzle and will always smell like
bad fish.
5) After screening the caps for electrolyte leakage and removing the bad
ones, ESR the remaining caps.
6) Scrape all of the black corrosion off of the traces and tin the exposed
copper, wash the board in alcohol, replace the caps, repair weak solder
joints at heat producing parts.
7) Now you can start troubleshooting, but the vast majority of problems
have just been fixed, including nearly all of the "gremlins".
Expect it to take about an hour and a half per board unless you do a lot of
them. We have it down to an average of 45 minutes per board but we go
through a few of these.
Many of the caps leaking electrolyte will test good otherwise. Often the
electrolyte itself, or the corrosion that it causes is the problem. I have
found that relatively few caps will have bad ESR other than those in the
power supply and vertical output stages. Replacing the small electrolytics
in the power supply and vert output areas and getting all of the ones
leaking electrolyte almost always solves the problems with these sets. If
there are other problems you will likely chase your tail if you don't do the
caps before troubleshooting.
Leonard Caillouet
Electronics World
Gainesville, FL
----- Original Message -----
From: "Paul"
To:
Sent: Friday, February 13, 2004 6:28 PM
Subject: [TechAssist] Re: Mitsubishi V6015R Proj TV (correction)
> Model is VS 6015R
> Paul wrote:This set is infested with gremlins.
Original problem in the customers house was no snd. no picture. Has had
every symptom from no start, to no filament, to picture tubes light but not
tuner no sound. Checked the power supply has 130v for the horiz. and 28v and
12v for the vertical I/C. Have replaced vertical I/C and lytics in vertical
circuit. One was leaking thought that was the answer. Have replaced the HOT
and rung the flyback xfmr. Have checked esr on lytics in the area of HV Xmr.
Have re-soldered all the heat affected areas. I had the set running with
sound and tuner working. Thought I had found everything. It shut down after
about a minute or two. When I turned it back on it lasted for maybe 30. sec
and the next time it was back to start and shut down. Checked I/C's on all
the heat-sinks for excessive heat.Nothing abnormal. Could use some ideas or
similar experiences. Paul
>
> Paul ,B Central TV&Video Grover Beach Ca.
>
>
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> Paul ,B
Central TV&Video
Grover Beach Ca.
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Paul ,B
Central TV&Video
Grover Beach Ca.
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