Re: Tech : Electrohome G08-003 image too big

John,

Yes, low HV will cause the image to be too large (commonly refered to as
"bloom"). Check the HV section, caps, header pins, trim pots, etc.

----- Original Message -----
From: "Zitt Zitterkopf" <zittware@hotmail.com>
To: <vectorlist@vectorlist.org>
Sent: Tuesday, February 22, 2011 9:44 PM
Subject: VECTOR: Tech : Electrohome G08-003 image too big

> I’m in the beginning of the process of restoring my Star Trek Captain’s
> Chair:
> http://www.austinmodders.com/modules.php?name=Forums&file=viewtopic&t=2724
>
> having purchase an untested board set and an untested G08 Electrohome
> monitor.
>
> My goal is to verify the boards / monitor as good before I being the
> recapping process.
>
> I verified the board set as working after some initial debug - displaying
> the vector graphics on my Oscope (see thread above).
>
> I received a untested G08 by Fedex ground a week or so ago and began
> debugging it Sunday. Initially; the monitor did not power up; and I detect
> both F400 and F401 as blown. I immediately checked the Deflection
> transistors and detected two of the transistors were shorted. I replaced
> them with NTE388 (subs for MJ21196G according to Bills Classic Arcade
> http://www.biltronix.com/Star_Trek_08.html ) on a quick run to Frys
> Electronics.
>
> I replaced the F4xx fuses with 4A Slow Blow as suggested by Bill and
> F700/600 with 2A slow blows.
>
> The monitor powered up and is vectoring the game; however, it only appears
> to be rendering a "zoomed in" image. IE I can see part of the sega banner
> and other graphics such as the plasma shots coming from the Klingons in
> attract mode.
>
> I've checked the transistors in the deflection portion of the deflection
> board and they seem to be good based upon the dmm diode test.
> I've measured most of the voltages except HV. +9.1 is a little low at
> 8.5V. +400 is low at around 350V but varies based upon vector images. But
> unsure that those would be the cause of the image issue.
>
> I'm not 100% sure as it's difficult to determine but it looks like the
> horizontal MAY be ok / unzoomed... and only to vertical is zoomed.
>
> I'm looking for suggestions as to what to check.
> John
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Received on Wed Feb 23 00:57:11 2011