PCB Repair Logs – Page 102

Twin Eagle repair log

May 012014

Another of muddymusic’s boards here.
This one had graphics issues around the sprites.

Looking as the MAME source you can see that the sprites are held in the MASKROMs marked UA2-3, 4, 5 & 6.
Probing all the pins on these chips revealed that pin 25 on three of these chips was floating. These are 23C2001 MASKROM’s which a datasheet is easily available for.

The last ROM had a signal at this pin and the other three are all linked off it so there is a break somewhere on this trace. I patched this line and tested.
Almost there but still a little issue around the text.

A bit more probing found that pin 11 (A1) of ROM UA2-4 was also missing. Again I patched this from the adjacent ROM and tested.

All appears to be working now.

Kicker (Shao-lin’s Road) repair log

Apr 292014

Bought this PCB (among others) from Ebay as untested/not working:

This, judging from the auction pictures and the GX477 serial, should have been an original Konami Shao-lin’s Road PCB but after dumping the EPROMs it turned to be a Kicker one (the overseas version).Anyway, before powering it up, a visual inspection revealed that one IC was missing:

Now, in absence of any schematics, looking at some PCB pictures on the Net, I figured out the missing IC was a M58725P SRAM pin to pin compatible with a 6116 (or 2016, 2018 etc..).Fitted a socket and a 6116 SRAM, I powered up the board (it uses the Konami Classic pinout, the same used for many other Konami games) and I got this:

These patterns of lines were changing on the screen sign that the board was running fine , infact I could coin-up and hear all the sounds but the video had some issues related to timing signals used to draw display, I presumed.

So, with the fear that one of many custom (with scratched ID) was bad, I started to test the ICs with my HP 10520A logic comparator and logic probe.All was fine until I came across a 74LS74 (location C6) whose ouputs was stuck low.Its data input pin (connected to an output of a 74LS161) had no activity at all but the near via which had to be connected to was pulsing!Infact my multimeter didn’t buzz on this and a closer look revealed this:

Bridged this broken track with a bit of solder, I powerer up the board again and I got:

Board 100% fixed and another classic one preserved!

Insector X repair log

PCB Repair Logs, Repair Logs 1 Response »

Apr 132014

Another one of muddymusic’s PCB’s.
Everything looks fine with this one until it is coined up then the game starts automatically.
If I enabled test mode by switching switch 3 on DSWA then I could see the start button for Player 1 was stuck on.

I initially thought this was going to be a sticking point as all the inputs go to a custom chip however I found that the trace from the pull up resistor array to the custom was broken somewhere.
There were no visible breaks so it must be under the silkscreen somewhere.

Running a patch wire from pin 2 of the custom chip to the resistor array fixed the issue.

Quite a fun game it is too.

Vendetta repair log #1

PCB Repair Logs, Repair Logs 1 Response »

Apr 122014

Got muddymusic’s Vendetta PCB. Game seems to play fine but the blue colour is missing.
Schematics are available for this game which made it simple to find the fault.
I could see all the inputs to the custom 052535 chip but the output of the SIL was constantly low.
I have a scrap Konami PCB that uses these so removed on and fitted it.
Board is now fixed

Spy Hunter repair log #3

PCB Repair Logs, Repair Logs Comments Off

Mar 122014

A quick one here.
Tested a CPU board with known good video gen board and SSIO board connected.
The game had no sync but it appeared the game was running.
Sync could be a bad fault to have as its heavily dependent on the PLD’s found on this board and I have yet to reverse them.
Luckily for me I found the last stage before being outputted to the monitor was to blame. The 7404 chip @ location C4 had stuck outputs, replacing this brought the sync back and the board was fine after that.

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