[TechAssist] Re: Mitsubishi VS4507R weird vertical problem
- From: "Damon" <DAMON101@xxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 17 May 2002 08:51:24 -0500
First re-estimate it so you get paid for this nightmare unit.
2nd check your +28 V at pin 8, and the same at pin 11, I think (vert pump
up).
Next, you MUST HAVE 10 or 11 volts at pin 1, if not there is a zener diode
real close to the pin that will cause vert collapse, stretching in the
middle....even if it's off by 0.2 volts!!
Since you checked the caps I assume you also checked the Vert B+ off the
IHVT.
Damon Brunger
damon101@xxxxxxxxxxxxxx
Telrad Electronic Services
Ft Wayne, IN 46815
----- Original Message -----
From: "Jorge Camboni" <geo@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, May 17, 2002 3:37 AM
Subject: [TechAssist] Mitsubishi VS4507R weird vertical problem
>
>
> Hi fellows, need your help on a Mitsubishi rear projection set, VS4507R
> model, it has a very weird vertical problem:
> a couple of inches wide very dark horizontal stripe, almost at the top,
> crossed by a few white, retrace-like
> lines, and that pattern is SUPERIMPOSED to the picture, which can be seen
> faintly in the background.
> also the vertical amplitude decreased just a little (top).After a few
> minutes, the
> vertical amplitude decreases some more inches, and power goes off.This is
a
> very technician unfriendly set,
> had to work with it at the customer's house, I managed to get the boards
> out and change all the
> bad and suspicious caps in the vertical section, (found a couple almost
> dry) and one dead
> cap in the power supply, checked all around the jungle IC, did a thorough
> resoldering and cleaning
> on the boards. All this job was not the most technical approach, but it is
> what you have
> to do first at the customer's place, and it was almost impossible to make
> serious measurements
> folded onto myself on the floor and struggling with a fierce cable-web
:o))
> I hoped for the best and failed....
> Found NO TIPS on this model. Service manual is out of question (gave them
a
> ridicously low estimate,
> hoping for usual LA7838 tale.. ), and to make a sad story worst, I can not
> bring this one
> to the workshop. SO...ANY HELP WILL BE SO MUCH APPRECIATED!!!!
>
> tnx in advance Jorge Camboni GY Electronics, Dallas (for so many years
> cx8bbh)
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