Caius

Lightning Fighters repair log #2

Jan 062015

Found this Konami Lightning Fighters PCB buried somewhere in the pile so today I decided to take a look at.

I know quite well this kind of hardware since I repaired two of them in the past and I can say it’s not really complicated, the use of graphical ASICs simplify a lot the PCB layout and troubleshooting.

Once powered on I got a solid black screen.Probing the main 68000 CPU revealed that watchdog was active and board was resetting endless.Dumped the two program ROMs gave me bad dump of the one @E15.Once reprogrammed a 27C010 EPROM, board succesfully booted but all colors were clearly wrong:

Schematics of this game were available so looking at them revealed that color RAMs were two 2018 @D18 and D19.Probing these two static RAMs I found some addressing lines not pulsing fine.All of these were tied to the four outputs of a 74LS157 @F19 (whose inputs were connected to address lines of 68000 CPU and ASIC marked ‘053251’ so this was how the two colors RAM were being addressed) .

Piggybacking a good 74LS157 restored all colors.Using my HP10529A logic comparator was a further proof of my suspects that were confirmed definitively testing this multiplexer out-of-circuit where it failed miserably:

Fitted a good 74LS157 brought back the PCB to 100%.

Vendetta repair log #2

Jan 022015

Got this original Konami Vendetta PCB from a batch of faulty boards I recently bought:

Board was really brand new as it was come out from the factory but once powered on I was greeted by a flashing white screen sign that the watchdog circuit was active and the board kept to resetting:

Usually the watchdog is on because there is some troubles in the main code execution.So I started with my multimeter the check the main CPU (a custom marked ‘053248’) area and found an high resistance between ‘D1’ (DATA LINE 1) of the CPU and the program ROM:

Obviously, for the proper CPU operation, all its address and data line must be daisy chained with the main code ROM as confirmed also by schematics:

So I used a provisional patch wire and board booted fine:

But external appearance matters too.So, following the path of this data line, I found the point where the track was interrupted (picture on the right was taken with USB microscope) and I patched it with some AWG30 wire:

Job done.

Super Pang PAL redump added and verified

PAL Updates Comments Off

Dec 282014

Today I dumped the only PAL from an original Super Pang PCB.Equations are the same of the ‘CW-P’ dump already in the database but device (a PAL16L8) is marked ‘POKER’ on mine board like the PAL from Pang dumped by me some time ago.Equations are the same of the Block Block PAL as well.Dump is tested as working in a GAL16V8 replacement.

The Maint Event repair log

PCB Repair Logs, Repair Logs Comments Off

Dec 252014

My friend Luca sent me this original Konami The Main Event PCB (a decent wrestling game):

After booted up game showed a clear sprite issue:

In these Konami boards sprites DATA are stored in 40 PIN 4Mbit MASK ROM so I went with my logic probe on the two ones @K4 and @H4 and found that the one ‘799B05’ @K4 has some DATA lines inactive.This was confirmed also by the MASK ROM test:

Reprogrammed the DATA into a 27C400 EPROM replacement gave me correct sprites:

Next issue to troubleshoot was the absolute lack of sound.Using my HP10529A logic comparator I found a 74LS74 @G5 with bad outputs but this was not enough to restore sound.Probing the audio Z80 CPU I found that all the control lines were silent so this convinced me to replace it (I had confirm it was really bad as I tried it in another board).At this point I had sound but only some speech samples randomly played.Analyzed the 2018 SRAM @F5 and found weird activity on DATA/ADDRESS lines.Desoldered and tested it confirmed it as bad:

Sound was finally fully restored.Last issue I had to solve was that some Player 1 inputs were not working, for example COIN 1 were stuck LOW as shown in TEST MODE:

As show in schematics inputs are handled by some 74LS253:

Probing the one @E12 with a logic comparator gave me problem on the two outputs, this was confirmed by out-of-circuit testing:

After replacing it TEST mode reported all the inputs working again:

So the board was 100% fixed.

Super Pang repair log

PCB Repair Logs, Repair Logs Comments Off

Dec 252014

Got this original Super Pang PCB from my friend ‘Mikidaffy1983’

He asked me to desuicide it (picture above is actually from the board already desuicided) and, as usual, I followed instruction here:

https://www.arcadecollecting.com/dead/pre-cps.html

All went good but when I tried the board I noticed wrong colors on some backgrounds/sprites:

Studying a bit the hardware I found that the color RAMs are located @8C and @9C (two 6116) so I started to analyze them with my logic probe, this revealed that some data lines of 6116 @8C were inactive.Desoldered and tested it out-of-circuit confirmed it was bad:

Fitted a good 6116 RAM brought colors to normal.

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