Re: Problem with Electrohome G07- only half picture

Ok, I think I officially found the culprit. This one was definitely
tricky. I checked the pots (V lin and V height) carefully, but I wasn't
thoroughly convinced they were bad. I did a test by wiggling the V. Height
back and forth and noticed for a second that the picture would correct
itself and then go bad. I checked R407 and visually it didn't look good
even though it tested ok at 4.7K. I replaced it and the picture was rock
solid. I twiddled all the pots and all seems good now. That resistor must
have been going bad. The other thing might have been simply resoldering the
Pots but I'm pretty sure it was R407.

phew! I think we're done now.

Matt

----- Original Message -----
From: "John Robertson" <jrr@flippers.com>
To: <rasterlist@vectorlist.org>; <rasterlist@vectorlist.org>
Sent: Wednesday, July 30, 2003 3:01 PM
Subject: Re: RASTER: Problem with Electrohome G07- only half picture

> Good point, I had not read deeply enough into your original post, I would
> agree that a bad linearity pot could cause 1/2 screens...my suggestions
> were for NO vertical deflection. Sorry!
>
> John :-#)#
>
> At 02:17 PM 30/07/2003 -0700, Matt Rossiter wrote:
>
> >I'm beginning to think now that I might have a flakey V. Lin pot or
> >something in that circuit is flakey.. Everything was fine until I
started
> >adjusting the linearity - then the left half of the screen slowly started
> >closing in. I'm sort of glad though - because typically games don't just
> >fix themselves permantly. Plus - I'm not quite so confused now about the
> >screen cut evenly in half. It could have been 3 quarters out or any
ratio
> >for that matter.
> >
> >Matt
> >
> >
> >
> >----- Original Message -----
> >From: "John Robertson" <jrr@flippers.com>
> >To: <rasterlist@vectorlist.org>; <rasterlist@vectorlist.org>
> >Sent: Wednesday, July 30, 2003 11:08 AM
> >Subject: Re: RASTER: Problem with Electrohome G07- only half picture
> >
> >
> > > Hi Matt,
> > >
> > > I would suggest that you recheck the capacitor job you did...I
instruct my
> > > staff to make sure the capacitors (particularly the larger ones) are
flush
> > > to the board to reduce the risk of breaking traces if the capacitor is
> > > jiggled in normal use/re-installation of board).
> > >
> > > I suspect the large cap on the vertical deflection circuit has a
cracked
> > > trace or possibly a cold solder joint. I see this every now and then
on
> > > boards that had someone elses' work on the capacitors...
> > >
> > > John :-#)#
> > >
> > > At 10:19 AM 30/07/2003 -0700, Matt Rossiter wrote:
> > >
> > > >This morning I took another stab at trying to fix this problem with
my
> > > >centipede monitor. This time I decided to unplug the yoke and start
> >tracing
> > > >signals from the yoke connector pins. I still had a hard time
finding
> >any
> > > >thing unusual. After about 20 minutes I re-connected the yoke - and
> > > >badda-bing! Out of nowhere I finally got a full picture on my
centipede.
> >I
> > > >honestly don't know what fixed the problem. I did take some readings
> >from
> > > >the wires on top of the yoke - so I figure maybe there was a loose
> > > >connection somewhere - but that doesn't seem to make sense why I'd
get
> >just
> > > >half a picture. I'm stumped - but at least my Centipede works!
(knock on
> > > >wood).
> > > >
> > > >
> > > >Matt
> > > >
> > > >
> > > >
> > > >----- Original Message -----
> > > >From: "Sean McLachlan" <sean@lithoflexo.com>
> > > >To: <rasterlist@vectorlist.org>
> > > >Sent: Monday, July 28, 2003 7:54 AM
> > > >Subject: RE: RASTER: Problem with Electrohome G07- only half picture
> > > >
> > > >
> > > > > You do if the monitor is mounted vertically. ;)
> > > > > I had a G07 that was doing the same thing, and one of the 400
series
> > > > > resistors was burnt open. I don't remember which one, it was so
> >obviously
> > > > > fried I replaced it without much thought. Rogers R420 suggestion
> >rings a
> > > > > bell, though.
> > > > >
> > > > > Sean McLachlan
> > > > > MIS Manager
> > > > > LithoFlexo grafics inc.
> > > > > 801.484.8503
> > > > >
> > > > > -----Original Message-----
> > > > > From: owner-rasterlist@vectorlist.org
> > > > > [mailto:owner-rasterlist@vectorlist.org]On Behalf Of SteveT
> > > > > Sent: Monday, July 28, 2003 8:58 AM
> > > > > To: rasterlist@vectorlist.org
> > > > > Subject: Re: RASTER: Problem with Electrohome G07- only half
picture
> > > > >
> > > > >
> > > > > Matt
> > > > > If it displays the right half of the picture top to bottom -you do
not
> > > >have
> > > > > a
> > > > > vertical problem.
> > > > >
> > > > > Matt Rossiter wrote:
> > > > >
> > > > > > Hey all,
> > > > > >
> > > > > > I brought home a Centipede that had a dead monitor. I replaced
the
> >caps
> > > > > and
> > > > > > installed a new HV unit. It now powers up, but only displays
the
> >right
> > > > > half
> > > > > > of the picture with a line running down the middle -looks like a
> >typical
> > > > > xy
> > > > > > failure but on a raster game. So, basically I have a vertical
> > > >deflection
> > > > > > problem.
> > > > > >
> > > > > > Here's what I've done so far...
> > > > > >
> > > > > > 1) Tested the transistors in the vertical output circuit - X401
and
> > > >X402 -
> > > > > > they test fine out of circuit. I believe the signals are good
too
> >when
> > > > > > testing in circuit.
> > > > > > 2) FR401 (the fusible resistor) is fine.
> > > > > > 3) Checked the signals on IC 501 and they look good. Swapped in
a
> >new
> > > >IC
> > > > > > just to be sure.
> > > > > > 4) Checked other resistors and capacitors within the vertical
output
> > > > > > circuit.
> > > > > >
> > > > > > I just can't seem to trace down the problem, but it could be
> >something
> > > > > > simple I'm missing. Has anyone else run into a similar problem?
> > > > > >
> > > > > > Matt
> > > > > >
> > > > >
> > > >
> >
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Received on Wed Jul 30 18:28:42 2003