PCB Repair Logs Mr Do! Bootleg

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Mr Do! (Bootleg)

Mr Do! (Bootleg)
Marquee mr do.jpg
PCB Image Reserved
Pin Out Reserved

Repairer: Arcade King
Forum Thread: Mr Do! (Bootleg) PCB Repair

Got this one from the USA for $10.50 USD, Not sure if its a bootleg or not, its marked MD01-1, I'm going to assume its a bootleg because the game works perfectly fine and does not have the security PAL chip at J2, I checked the bottom of the board to see if there was any sign of the PAL chip ever being there but it would appears there never was. I would rate this boards condition as immaculate.

On first inspection I noticed 3 things wrong, the 20 Mhz crystal was held to the board with tape with the legs broken off. Next was a missing SN76489AN which is a sound chip lastly the PAL chip.

Replaced the crystal and fired her up game was perfect except some missing music but I don't have a replacement sound chip ATM. I have another Mr Do! this one is a original Universal board marked MRD-1102. I did a test to see what would happen if I removed the Pal chips and as I suspected the game graphics went all screwy.

Think I'll keep this bootleg and sell the original as I don't know if that PAL chip can be replaced or not.

Update: Found the SN76489AN's on 2 scrap boards I have, A Choplifter and Wonderboy in Monster Land PCB another Mr Do! fixed

16/9/2007 Mr Do! Bootleg MRD-1102

Had this pcb for a few years sitting in the cupboard waiting for some day when ICBFed fixing it. Thing was all the tri state proms had broken legs (4 of which) and at the time I did not have replacement proms (82s123 or 27s19 32x8) or a programmer to that programmed proms....how things change.

Pulled it out and toasted up replacement proms and put a z80 back on it I pinched for another pcb, fired it up and......NOTHING....

Using the trusty logic probe I went straight those any shitty F branded Fujitsu TTL's and straight away found 3 dead 74ls04's @ L2( something to do with the CPU(Wait)), R7 (gave me sync) and D9(NFI)

At this point still no video but using the scope I could see the program and gfx were running. Found a dead 74ls148 @ R9 which gave me picture game is running but with glitches.

Problem: Game kept resetting and sometimes would not start and eventually wouldn't start at all.
Fix: faulty 74ls04 @ B1 which leads to the CPU reset, I could see using the logic probe it was flaky.

Problem: Character sprites would disappear when characters overlapped in the same vertical row (see vid).
Fix: tough one to nut out but was a missing 220p disc cap @ C101

Problem: some sprites were flickering.
Fix: added a 100p disc from ground(pin 8) to pins 7 and 9 on a 74ls153 @ A5. Seen this on my other Mr Do! pcb. Theres also disc's on B5 ground(pin 8) to pin 9 and D5 same pins.

Problem: Sound very faint.
Fix: Bad LM324 @ E1

Notes: also had to put a MB3712 amp back on as I pinched the one on here for another board yonks ago.

Decided to do the Jrok high score mod to this pcb which can be found http://www.jrok.com/sohs/mrdo_shs.html Be aware if you have a bootleg you need to also reprogram roms 3 and 4 to match the original Mr Do!(mrdo.zip) in mame.

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