Major Havoc repair log

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Guest

Guest
Archived from groups: rec.games.video.arcade.collecting (More info?)

I posted a few weeks ago about my poor Major Havoc PCB that decided out of
the blue to stop responding to input from the spinner (Space Duel
conversion). It's strange because at startup the spinner DOES work but once
you start a game response steadily declines to the point that it no longer
works at all...

Anyhow, I was getting an error on the self test pointing to location 13Q
which is the Quad Pokey Eliminator. After tinkering with the Pokeys and
finding that they are good (swapping in known good ones and also swapping
mine out to another PCB), a search of Google found that the LETA chip
137304-1001 could also be a suspect since it is the chip for the spinner
control (also does trackball control on games like Crystal Castles). The
LETA chip resides under the Quad Pokey Eliminator board on the MH PCB. I
found a spare Crystal Castles PCB that was only good for parts offered on
RGVAC by Scott B. on a FREE FRIDAY offering (Thanks Scott!). It arrived
today. I desoldered the LETA chip from the CC and plopped it into my MH
only to have the same problem - URRGGHH! What else could it be...???

Another few hours on Google found an old posting from Jess Askey who stated
that low +5v can cause the LETA to act funny which can cause odd spinner
response. I checked my +5v and sure enough, it's only at 4.8v. Being the
not so electronically skilled person that I am, I had no idea how to adjust
the voltage on the ARII PCB. Yet ANOTHER search of Google provided that
answer - there is a small trimmer pot on the ARII PCB that controls the +5v
and a simple tweak of the pot yielded a good steady +5v reading and VOILA!
My Major Havoc is again playable. Yea!

Thanks to all on RGVAC who share their finding - the archives of these
postings (some of which are 8-9 years old now) are still helping us dummies
fix their games.

--
-Steve P.
 
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Guest

Guest
Archived from groups: rec.games.video.arcade.collecting (More info?)

Nice!!
Now if I can only find a Space Duel>Major Havoc CP so I can actually
play mine. My MH PCB has been sitting on a shelf now waiting for one to
come along to no avail. It's been like almost 20 yrs since I've played
the game without using MAME.
Jason