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Street Fighter II Hyper Fighting repair log

Aug 232010

Got this board off ebay, sold as having graphics corruption. There was slight corruption on the title screen and a fair bit in-game, shadows were the worst part but the Ryu character suffered really badly too.
As I have a spare board set for CPS1 games I started by swapping the B board over from a champion edition board. The fault disappeared
I swapped the 3 eproms over from the Champion Edition board to the Hyper Fighting board (these are the only difference between the 2 games) and the fault came back.

I know the first picture is from a Champion Edition, I had the CE ROMs fitted at the time of taking a picture

There is not much to the B boards so took a wild guess that the problem was with one of the 42 pin maskroms. I systematically swapped them over one at a time tested the board after each swap. Turns out that the very last maskrom has one of its address lines stuck, swapped this one for the one off the donor board and all fixed. Replaced the 3 eproms for Hyper Fighting and all the faults are now cleared up.

Bubble Bobble repair log #1

PCB Repair Logs, Repair Logs Comments Off

Aug 012010

This game was completely DOA. Checked the clock signal, all fine. Checked /RESET line of Z80, stuck low.
I replaced resistor R30 (330ohm) which is part of the Z80 reset circuit, it fell in half on removal.
The /RESET was now HIGH but all the address line were stuck.
I pulled both the Main and Sub Z80’s, both failed tests.
Also found 2 dead EPROMs. Burned 2 x 27256 eproms( a78-07 and a78-08)

All seemed to be firing up after that.

X Multiply repair log #1

PCB Repair Logs, Repair Logs Comments Off

Aug 012010

Started off as a physical problem with corroded legs on MASKROM’s giving corrupt graphics on sprites.

Three legs were corroded on MASKROM T44.00, which is an NEC 23C1000. After a little asking about, I was told the EPROM equivalent was a 27C301 (non JEDEC).
I obtained a 27C301 eprom and burned a T44.00 from MAME. Pretty much all the graphics were back but there were some white blocks around the ship sprite and certain enemy bullet sprites. Found a broken track from pin 20 (chip enable). Repaired this and the white boxes are now gone from the ship sprite. There were still white boxes around the projectiles. I have now confirmed that with an original ROM the game works fine.

I took a closer look at the pinouts from a 23C1000 MASK ROM and a 27C301 EPROM. MASKROM’s have less pins than their EPROM equivalent mainly due to not have programming pins but also this ones only has one enable pin (pin 20) and the EPROM has separate /OE and /CE pins. I lifted pin 2 and soldered a wire from this to pin 22 on the EPROM and fired the game up, all the graphics are now 100% working. I initially thought this corruption was down to the speed of the EPROM but now I know otherwise.

Graphics fault

Fixed

Bomb Jack repair log

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Aug 012010

Received an “untested” Bomb Jack board from eBay.
It appears to be a bootleg/original hybrid. The A board was a bootleg, the one with only 2 x AY-3-8910’s on it and the B board is from an original.

The game was missing the green and blue colours and sound was stuck in a constant repeating loop from power up.
The RGB, sync and video ground go to a 5 pin header on this bootleg, not a 6 pin header, the previous owner was clearly not had an adapter or plug for anything on this board and had soldered the wires directly on, had also melted all the plastic supporting these 5 pins so a couple were shorting to ground, easy fix. The sound had a corrupt EPROM, I erased and burnt a new one, still no change. The RAM had already been socketed so I tested it and it came up clear. Checked the Z80 with the logic probe and found the address lines were all high except for a couple that were pulsing. De-soldered it and tested it, it failed on pretty much everything, replaced it and now the sound was working but seemed to be lagging behind when compared to MAME. I put in a new RAM and the fault was fixed. Swapped the RAM back and fault returned. This RAM works fine in my other boards so am putting it down to RAM speed.

Double Dragon repair log #1

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Aug 012010

Got a broken DD board off Ebay. Original fault was the picture was white with black blocks.

The board had many repairs done in the past, some bad some good, so I started by removing them all and checking them through. One of them was a length of kynar replacing a lifted track but was going to the wrong place! fixed that but made no difference at all.
Some of the RAM had been socketed but had used badly cut down sockets, replaced these also.

After a long time inspecting the underneath of the boards and fixing a LOT of broken tracks I noticed a few chips on the CPU board had a lot of flux around the solder points but no sockets had been fitted here. They were all 74LS273 chips and one was a Fujitsu! Put the probe of the Fujitsu chip and most of the pins were dead. Desoldered to find a lot more broken tracks. Tested the old chip, it failed miserably. Put a socket in, pulled the schematics for the CPU board and repaired all the tracks that were broken. New chip inserted and fired it up, all back to normal.

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