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Mikie Repair Log

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grobda View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote grobda Quote  Post ReplyReply Direct Link To This Post Topic: Mikie Repair Log
    Posted: 02 Sep 2018 at 1:51pm
Some capacitors and the volume pot were missing, so I replaced these.

The game booted but with corrupt background graphics. It wouldnt coinup and in when set to freeplay it would play but character would not move left. The sound was completely missing.

Graphics;
 I looked at the schematics and found the control logic for the graphics ROMs. Probing various chips around this area found a LS86 @9F with stuck outputs. Piggybacking this made a small difference so pulled it and it failed. Replacing it made the graphics  slightly better. Then found a ls174 at 9G with dead outputs. Replacing this restored background graphics but some colours looked off and there was an interference pattern appearing that got worse with time. Probing back from the colour proms I found another LS174 at 7I with dead outputs. Replacing this restored the graphics.

Inputs;
Coin and p1 left were both multiplexed through a ls253 at 3E. Replaced this and inputs started working.

Sound;
Amp was dead (finger test) replaced it and got speaker hum but no sounds. The Z80 at 4E is the sound CPU and was getting clock signal and reset pulse at boot but did nothing. Suspected it was dead so replaced it and some sound returned but some random sounds were playing and the music was missing. Suspected the 6116 RAM at 7E so pulled it and it failed. Replacing it restored the sound properly.
sporadically obsessed with this sh*t
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Shinydaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shinydaz Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 1:54pm
Sweet, love this game !
Out of room but always room for one more !
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grobda View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote grobda Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 2018 at 5:01pm
Still Fixing Mikie PCB's, here's some info on the PCB;

Locations of IC's with chip names scrubbed off;

Top Board;

9A - 68A09 - Main CPU
10F - 6264 - Main RAM (Marked 5533 on schems)
4E - Z80 - Sound CPU
7E - 6116/2128 - Sound RAM (Marked 2009 on schems)
5C/6C - 76489 - Sound chip

Bank of 6 eprom sockets are program roms, 3 or 5 will be populated depending on size (64 or 128)
Single eprom next to 6116 is sound prog (2764)
Bank Of 2 Sockets are Character/Background Roms (2x2764, or possibly 1x27128)

Bottom Board;

14A - 6116/2128 RAM
15C - Konami 085 Custom

Bank of 8 eproms are sprite roms (8x2764 or 4x27128)

Isolated an slightly cleaned up the sound section of the schematics for ease of use;







Edited by grobda - 15 Sep 2018 at 9:50am
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Shinydaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shinydaz Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 2018 at 5:13pm
Great info, I'm still on the hunt for one.
Out of room but always room for one more !
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TheDaddy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TheDaddy Quote  Post ReplyReply Direct Link To This Post Posted: 08 Sep 2018 at 5:38pm
Nice one. Thanks for sharing, Always comes in very handy.

Dave.

P.S I have a Whizz(Twin Falcons) on the bench tomoz. Cant wait !
AKA Wonderboy.
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