[TechAssist] [ FIXED ] Mitsubishi CS-40503 has intermittent Vertical collapse after warm-up.
- From: "LeRoy Westlund" <llw@xxxxxxxxxx>
- To: "TechAssist" <techassist@xxxxxxxxxxxxx>
- Date: Sat, 27 Mar 2004 00:47:52 -0700
The fix should have been an easy job,....but,...here's what happened:
I found a tip early on, that said to check R468 (1 ohm 2 watts)( +37 volt
source).
When I checked it, I just measured across it with an ohm meter, and when it
didn't check open, I assumed it was OK. Problem was that even though the
connections looked good, there was a weak connection on one end of it. I
should have removed the old solder, before resoldering it. That was my FIRST
mistake.
The second mistake was even WORSE !
In the process of removing and checking all the e-caps in the Vertical, and
SMPS,...I checked the TWO tandalums C443, and C444. As we ALL should know,
the Tandalums have the + side marked instead of the - side. Somehow,....(You
guessed it),..I had managed to install them back in the reverse position. (A
senior moment, I guess ),...that cost me much wasted time, in finding the
remainder of my problems.
I was lucky to find my mistake, buy using a can of circuit coolant, since
the problem was heat related. Picture was OK for the first 5-7 minutes, then
it would come up from the bottom for about 2 inches, and the vertical lin.
would become stretched at the top.
Touching the 2.2 tandalum with a cotton swab soaked with freez-spray, helped
me pinpoint the problem.
The only good thing that came out of this experience, was that my original
estimate of $150, for an easy vertical problem, was increased, and approved
for $300. I know my estimate was too low to start with,...but,....maybe
someone was watching over me afterall,...and just helped me get the estimate
up to a more normal level for this set.
After all,....I had to stand on my head for 6 hours, and hang from a skyhook
for another 8 hours to even find a decent way to troubleshoot this monster.
At any rate,...I want to thank all of you who helped,...and especially Ed,
for sending me a pdf. of the Vertical ckts.
BTW;.....C454 (150pfd.), is not needed, and is not used in the 40 inche
chassis. It shows it to be there in the 35 inch version that Ed sent me. I
tried it with, and without C454 in the ckt., and it don't seem to care if
it's there or not. (C454 is a feedback cap., from output to input on the
vertical IC (LA7833). It was not in the circuit to start with,....so I left
it out. The set has been running perfect for 8 hours. I'm convenced it's
fixed.
Thanks again to all who helped me.
LLW
LeRoy Westlund
Westlund TV & Electronics
97 North Main "Where there's a will,...
Centerfield, UT 84622-0087 There's always a way."
Ph./Fax 435-528-3822
mailto:LLW@xxxxxxxxxx
-----Original Message-----
From: LeRoy Westlund <llw@xxxxxxxxxx>
To: TechAssist <techassist@xxxxxxxxxxxxx>
Date: Wednesday, March 17, 2004 2:43 PM
Subject: UPDATE : Mitsubishi CS-40503 has intermittent Vertical collapse
after warm-up.
>Hi members,
>I'm still struggling with this 40" Mits.
>I need some additional help.
>I have replaced the Vertical out IC (LA7833), and repaired all bad looking
>connections.
>I replaced a couple of E-caps, that I thought for sure would fix the
>problem, cause they tested bad.
>The problem has shifted from intermittent vertical after warm-up, to a
solid
>2" vertical deflection problem in the middle.
>I need someone to look at the schematic of this set, and provide me with a
>list of all the e-caps in the vertical ckt. I may have missed checking one
>somewhere along the line. Also, I see that C-454 is missing, but if I
>remember correctly, it was never there to start with, unless it fell out
>when I removed the solder. If it needs to be there, then I need to know the
>correct value, so I can install a new one.
>
>Thanks for taking the time to help me.
>I am trying to fix this one on the floor, cause I have no help to lift it
>onto the bench.
>I have pulled the chassis 3 times, and would like to be more successful on
>the 4th attempt.
>
>LLW
>
>LeRoy Westlund
>Westlund TV & Electronics
>97 North Main "At least I'll go down
>Centerfield, UT 84622-0087 swingin,......what a swingin
>Ph./Fax 435-528-3822 way to go."
>mailto:LLW@xxxxxxxxxx
>
>-----Original Message-----
>From: LeRoy Westlund <llw@xxxxxxxxxx>
>To: TechAssist <techassist@xxxxxxxxxxxxx>
>Date: Friday, March 05, 2004 12:53 PM
>Subject: Mitsubishi CS-40503 has intermittent Vertical collapse after
>warm-up.
>
>
>>Hi members,
>>This Mitsubishi model CS-40503 has an intermittent vertical problem, after
>>warm-up.
>>I re-soldered all pins on the LA7833 vertical IC even though they looked
>OK,
>>and could find NO bad connections in the 400 series area. I replaced ONE
>>e-cap 100 @ 35, even though it tested OK.
>>I am going to order a new LA7833 vertical IC, but for some reason, I don't
>>think it will cure the problem. I see a couple of Tantulam caps in the
>area,
>>but I think those kind of caps never go bad,..and of course in this case
>>they test good.
>>Does anyone have any case history of a vertical problem on this set ?
>>Also,...does it have a PIP module in it ? ( I don't recognize any.)
>>Video looks good anyway, so I wouldn't suspect a PIP problem.
>>
>>TIA,
>>LLW
>>
>>LeRoy Westlund
>>Westlund TV & Electronics
>>97 North Main "At least I'll go down
>>Centerfield, UT 84622-0087 swingin,......what a swingin
>>Ph./Fax 435-528-3822 way to go."
>>mailto:LLW@xxxxxxxxxx
>>
>>
>
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