[TechAssist] Mitsubishi Tv CS2723C chas WM1-A-C23R, thin lines down left side of screen [FIXED]
- From: Gary McCartney <number63@xxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Fri, 20 Sep 2002 18:50:36 -0400
This set had two problems,
1- thin shadow-like lines at left side of screen going all the way from
bottom to top of screen.
2.- A hum bar going all the way across the screen which is also like a
shadow and slowly crawled up the screen. I didn't notice this problem
when I first worked on the set, so I was thinking all along that it was
possibly my fault.
Solutions:
1.- for the thin lines at the edge of the screen, I found R593- 390 Ohm,
2W - was open. R593 is located in parallel with L551, going to pin 2 of
the yoke connector to the horizontal winding. I only found it by
noticing that the coloring of the resistor was off a bit and just took a
chance at removing it to measure it.
2.- for the hum bar across the screen, this was a result of my own
making while I was trying to find the fix for the other problem. I had
changed many elctro. caps on the deflection board and when I noticed
this hum bar, I started back-tracking by putting the original caps back
in, hoping that one of my new caps was defective. Well, it turned out
that C218, a 10uF
25V bi-polar cap was missed when I put the original caps back in. I had
replaced the original with one from a scrap chassis because I didn't
have a new one at the time. It did measure ok with the ESR meter so I
didn't think there would be any problem using it. I found the solution
by scoping D551 and saw a waveform which was similar to a sine wave and
when I turned the flyback screen control up and down, the waveform would
go higher or lower in amplitude. This coincided with the hum bar only
appearing when there was a bright scene. D551 and C218 are located at
the bottom of the HV winding from pin 8 of the flyback.
Thanks to all who replied with suggestions, and especially to Charles
for providing the much need technical information :)
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: number63 (at) inetsonic.com
I may be starting to get somewhere on this now.
With video from test generator connected to video input, the band on the
screen stays in one position, it doesn't roll. If I adjust the screen
control on the flyback, I can make the band go up or down the screen
depending on which way I turn the control. If I adjust focus, it does it
just a bit, maybe moves it an inch or so. I'm wondering if I could have
an ABL problem, or maybe even leakage in the flyback?
Does anyone have a partial schematic for the flyback/ video circuitry
they could email me?
I found the SAMS listing as # 2919
Thanks,
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: number63 (at) inetsonic.com
My second updated message:
Well, I really felt that I had a chance to get this problem fixed with a
new STRS5141G regulator. I installed a new one, and it's the exact same.
The washed out band which crawls up the screen is what is bothering me
the most, because it wasn't there when I first got the set running. Does
anyone have any ideas on this?
Thanks.
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: number63 (at) inetsonic.com
My first updated message:
I have now replaced every electrolytic cap on the deflection board
except for the one by the standby transformer and the one by the relay.
Also replaced every elctro. cap on the CRT board. Still have the lines
at the left side of screen.
Today, as I was replacing some caps, I noticed another problem. On
brighter scenes, there is a 6" high band across the screen which slowly
rises up to the top of the screen. When this band is seen, there is no
chroma inside of it, and the video is washed out inside of it. Also
inside the band, there seems to be a bit of ripple from the horizontal.
This wasn't apparent for the first while I was working on the unit, but
I don't have any idea if I did something to make this problem or not, or
if was there all along and I just didn't notice it. I back-tracked by
re-installing all the original caps from the point where I knew I never
saw the problem. I am somewhat suspecting the regulator IC, STRS5141G
but I don't have one in stock. While I was at it I replaced the vertical
output IC LA7838. Nothing has helped. Made sure I installed all my caps
with the correct polarity.
Thanks for any help.
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: number63 (at) inetsonic.com
My original message:
This is a 27" Mitsubishi TV model CS2723C, chassis WM1-A-C23R. On the
very left side of the screen, there are about 8 faint lines that run up
and down the whole height of the screen. These lines are about 1/4" wide
and spaced apart by about the same amount or a bit more. They only show
up under certain screen brightness and colors. I have changed about a
dozen caps in the power supply and around the flyback, etc. Some of
these caps smelled fishy.
Does anyone have a tip with a specific part that has solved this
problem? I've spend too much time on it.
Thanks for any help.
--
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
email: number63 (at) inetsonic.com
------------------------------------------
To REMOVE your email address, click here:
http://www.tech-assist.org/unsubb.html
To CHANGE your email address, click here:
http://www.techassist.net/forms/change.html
------------------------------------------
***NEW*** Tips Added Instantly!!!***
Submit Repair Tips here:
http://www.tech-assist.org/secure/tip/
Other related posts:
- » [TechAssist] Mitsubishi Tv CS2723C chas WM1-A-C23R, thin lines down left side of screen [FIXED]
