Star Tech Journal

Issue: 1992-January - Vol 13 Issue 11


January 7992
STAR*TECH Journal
Electrohome
G07Poor
Filtering &
Vertical
Collapse
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CALL
STAR*TECH JOURNAL
FIRST FoR ALL VouR
TEST EQUIPMENT NEEDS
DIGITAL MUTIMETERS
PARTS TESTERS
CAPACITANCE CHECKERS
OSCILLOSCOPES
LOGIC COMPARATORS
609 /662-1080
OR FAX
--j;;;-t\q~iiil!i4
609 /662-0537
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Also: While you've got that moni-
tor on your bench , here's a list of
some caps that are probably
"baked" open but don't really have
any adverse effects on the pix
quality itself but do provide some
filtering and you've already got it
out, right, so ...
C706 ( 4. 7u @ 250v
on neck board)
C005 (4.7u@ 160v)
C529 (4.7u@ 160v)
C203 (220u@25v)
1191 :!i
1
1
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Address Changes
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C~33 _ _
Illustration 1
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January 1992
STAR*TECH Joumal
Prince's Corn.er
Donald B. Prince
D&RMusic
Bozeman, Montana
Bally/Midway Spy Hunter Blues
The Z80 System
SUBJECT
I recently had the rare pleasure of working on all
three of the Spy Hunter uprights that we own, at
the same time! If you have ever disassembled Bally/
Midway's three board over and under and under
setup, you know what I mean by "pleasure".
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u
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The hard part is not taking the boards apart, but
the reassembly. It's like trying to refold an old map.
Difficult at first, but, this experience was good for
more than learning how to refold an old map. More
importantly, I learned something additional about
theZ80,its support chips, and this particular Bally/
Midway system (which is the same setup used in
Tapper).
30
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...
-
10
11

12
13
141
No video, raster only on monitor. Theme music
plays, but no coin input registered (coin counter
doesn't count, no audio response).
The first likelihood was the +5vdc was missing, but
after measuring all the voltages, everything was
fine.
... 40
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A,,
SYMPTOM
TROUBLESHOOTING
4.,
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The next likelihood was a bad processor or a ROM
bad. I changed the Z80 and the first Spy Hunter
came up and ran fine.
The other one, there was no change, since I had
another board on hand, I changed the CPU board to
eliminate the video board. The game came up,
- .... •
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