TECH: Frenzy ZPU questions

[JDM]

OK, since I've fixed my Qbert I just had to get another project, this
time 2 Frenzys to make one. The ZPU is missing in the one cab, and the
other one has the normal battery acid damage, although light compared to
some of the boards I've seen.

When I go them home, I clipped off the NiCad and washed the board down
with the vinegar/water mix, and scrubbed it down with an old toothbrush,
followed by a water rinse. The corrosion is fairly minimal, but after
drying really well and plugging the board back in, I checked everything
else (fuses, etc.), crossed my fingers and turned it on. The LED lights,
but there is no blinking and no tones, but I hear the amp hiss in the
speaker. The screen is filled with multi-colored bits. The only thing I
have done so far is removed the reset button, since the corrosion ruined
it and had it permanantly turned on. This is really the only part that
was badly damaged by the NiCad, but I re-soldered all the connections in
the area below just to be sure. I'm getting all the right voltages from
the PS and no ripple. Also, the other boards look great...no corrosive
gas damage.

Has anyone out there have any experience with these boardsets, and can
they tell me basically what direction to start, or if this symptom is a
problem from elsewhere? Is there any repair logs out there that I can
tap into? I've looked the past 3 evenings online, in the group archives,
google searching for both frenzy and berzerk and have turned up very
little. Seems like there is not much on Stern games, or I'm just not
looking in the right place...I have a full Frenzy manual and schematics
sheets,

Please help! and thanks in advance!

Jeff

[Mark Hooks]

I'm in the same boat as you. I spend 5 hours on my Berzerk to play it 5
minutes. Did I mention they really named these games right? Anyway, the
ribbon cables are notoriously bad. It wouldn't hurt to get a new set. I've
found that the header pins tend to get corroded too. Sometimes it isn't too
obvious until you get it under a magnifier. Also, did you check all the
voltages on the boards? The power supplies are a weak point as well. It
doesn't sound like your processor is running since the LED isn't giving any
diagnostic flashes on bootup. Beyond that I'm not a lot of help. Good luck
with it and post us some tips if you make progress.

Mark Hooks

"JDM" <cannonDONTWA...@netscape.net> wrote in message
news:70_Be.302$xe3.144@trndny09...

[Matty-t]

Swap the CPU chip itself with a known good, and check the reset line
and clock. Thats a good start for a locked screen with garbage.

- Matt

[Matty-t]

*AHEM* before I get hopped on, that is AFTER you perform the obvious
checks on the PS voltages, etc, as you plan to do already.

- Matt

[Matt J. McCullar]

I worked on a _Berzerk_ boardset a couple of years ago and it had a bad
transistor on the power supply that kept the processor from resetting.

[Ball Breaker]

I had a Berzerk do the same thing a few years back. It was the LS244
addy. buffer at B6.

Good luck.
Tim in Va.