Re: Gravitar text color/WG6100 issue

Regarding the jitter problem...

Check the output of the 7815 and 7915 regulators (VR1 & VR2) in the video
section of the game board. If one of them is shorted through, jitter will
result. I had a board with this fault and replacing the two regulators
fixed the problem. Also good to do is replace the caps around these two
regs (C111, C121 & C110).

On the monitor deflection board, make sure that all 4 diodes D100, D101,
D102, D103 are all good. An open diode will result in halfwave
rectification instead of fullwave and this will result in a lot more ripple
on the DC power supply lines. If you haven't already, replace C100 and C101
(4700uF, 50V). A lot of standard cap kits do not include them because they
are the largest and most expensive ones. They are very important however.
I have posted an extensive replacement parts here:
http://www.biltronix.com/arcade_electcomp_01.html#wg6100_rebuild_parts

If someone has added an additional ground lead somewhere, just temporarily
remove it. These add-on leads often cause jitter issues because they can
create a ground loop as well as other issues. If removing the extra wire
solved the problem, there are better ways to beef up the ground connection
such as replacing the existing terminals in the original harness connectors
with new gold ones.

Text color problem...

Try adjusting the bias and gain pots on the 6100 neck board to get the
correct color balance. There is a pair of pots for each color. The manual
for the 6100 explains these adjustments.

And yes, some text is light blue (cyan). Screen shots (probably mame) on
KLOV:
http://www.arcade-museum.com/game_detail.php?game_id=8000

William Boucher

----- Original Message -----
From: "Andre Huijts" <a.huijts@upcmail.nl>
To: <vectorlist@vectorlist.org>
Sent: Saturday, March 13, 2010 2:25 PM
Subject: Re: VECTOR: Gravitar text color/WG6100 issue

Forgot to mention that I also replaced the pots on the Gravitar game PCB to
see if these were the cause of the jitter, but they weren't.

Op 13 mrt 2010, om 20:18 heeft Andre Huijts het volgende geschreven:

> Gravitar owners, I've been working on a WG6100 in a Gravitar and I wanted
> to know, do we agree that the main texts on the attract screen are meant
> to be light blue and not pure white ?
>
> When I compare the texts with f.i. the diamond test screen, the diamond
> screen looks like true white.
>
> Can someone confirm this ?
>
> Another question about WG6100: this one has a very minor "jitter" on the
> screen. I'd say that there is very small (extra) AC on the deflection
> signals. It looks like it's mainly on the horizontal deflection but also
> somewhat on the vertical.
>
> It causes the beam to not steadily hit the same dots on the screen. Note
> that the metal screen is INSTALLED on the HV cage !
>
> Any idea where to look. I just did a cap-kit on deflection and HV board
> (using Panasonic high quality caps, 105 degr.).
>
> I did not yet install a LV2000 (it's on it's way). Could it be in the low
> voltage section ? I did _not_ replace the caps there because the LV2000
> will get rid off them anyway.
>
> I've moved out the monitor out of the cab and ran it, and the issue is the
> same so it's no cause inside the cab, it's on the monitor itself.
>
> Any tips welcome, thanks
> !---------------------------------------------------------------------------
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André Huijts
andre.huijts@upcmail.nl

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Received on Sat Mar 13 15:10:23 2010