repair log – JAMMArcade.net

Thunder & Lightning repair log

Aug 152024

Got a Thunder & Lightning, a nice ball and paddle game from Seta on the bench today.

At first glance the board looked fine, but there was some worrying rusted pins on one LS close to the 68000 … not sure why, but other chips around weren’t affected.

I replaced the chip and patched the traces with some kynar wire.

When powered up, a working game displays a moving patchwork of tiles for a few seconds before displaying the title screen. In this board case, the tiles patchwork was displayed, but it kept rebooting just before displaying the title screen.

On this board, dipswitch 1 of the first bank puts the game in test mode. Doing so displays a color grid, and after pressing a button you get to the input test. The board worked flawlessly in test mode, meaning the main CPU worked enough to run it. But when pressing the reset button on the board, the following message started to show: “Address Error 2020E6”, before rebooting again …

Not knowing where this address pointed to, I looked into Mame to find the memory map of the game. And I found something very interesting : a PALCE is used as a protection device, using some address lines as inputs and computing a value that’s grabbed later by the CPU … if the value isn’t the one expected, a soft reset is done. That looks reaaally familiar !

Here’s the offending chip (TL-9) :

It was removed …

.. and replaced by a GALV16V8, using the file from the PLD archive. I added a support just in case.

And voilà !

Played a few levels to be sure nothing’s amiss, all is good !

Namco Rompers repair log

PCB Repair Logs, Repair Logs Comments Off

Aug 032024

I’ve had this board in my collection for some years and I’ve made some repair work on before (replacing the cus120 on the CPU board, might put up a repair log on that as well).
I was going through my PCB collection and found that the game would not boot, there was only a black screen and not even the usual klonk sound as Namco System 1 games usually do.

Started with the basics, probed the Program ROMs with my logic probe and I did see some activity on the address and data buses.

Decided to dump the Program ROMs and verify them and they turned out to be ok.

So I started to probe the address and data buses again and found an address line (A2) that was stuck low.

Traced this line back to a 74LS244 at E10

74LS244 is a buffer and according to the Pac-Mania schematics, pin 14 is the output which has its input at pin 6 and there was activity there

This made me quite certain that the 74LS244 at E10 was bad.
But just to be certain, I removed all Program ROMs and the Custom key chip, so none of them would interfer.

And the fault was still there.
I quickly desoldered the 74LS244 and tested it with my tester as bad

I soldered a socket in its place and replaced the IC with a known good one and now the game booted up again

Operation Wolf repair log #3

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Apr 102020

Another few Operation Wolf boards in at the moment. This one is from Unit504.

There is a nice little tag on this telling me the faults which really helps me keep all these boards together and where to start looking.

First job was to look into the gun shot register issue.
I did a quick test and could see the screen flash when the trigger was pulled so I knew that wasnt the fault
Following the circuit I come to the 74F74 IC which is used to latch the gun co-ordinates.

I normally wouldn’t start looking at this part but it was already socketed so decided to pull the chip and test it. It failed an out of circuit test.

I replaced this with a 74ALS74 and it seems to be be fine.
Now all the gun shots register as expected.

Next onto the sound.
None of the sounds were working at all and I didnt believe that all the seperate circuits for making sounds would be dead so looked a bit closer at the CPU side of things.
First off I checked the ROM and it dumped out fine.
Next the RAM. An inspection of the RAM showed signs of corrosion

I removed and tested it and thankfully it failed

Looks like that corroded pin has broken contact somewhere. Anyway, replacing the RAM brought all the sound back to life and completed this repair.

Lightning Fighters repair log #4

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Mar 242020

I got a Lightning Fighters PCB with GFX problems. As you can see, major colors and layers issues:

1) Probing the Konami 053251 custom chip revealed some weak signals on a few pins. This chip is a priority encoder, it deals with colors and layers and seems to be prone to failure in more and more boards of that generation. Unfortunately, you have to find a donor board of the same era to get a working one (good thing anyway is that it is used in a pretty good amount of Konami games).

Here is the result after swapping it with a good one:

2 & 3) Colors and layers are now fixed but we have some jailbars on sprites. This looks to be a sprite’s data issue. Probing the mask ROMs revealed missing signals on a few data lines for 939A05 and 939A06 ROMs. I replaced them with two burnt 27C400 EPROMs. Board is now fixed:

Here is an overview of the chips I had to replace on the board:

Rastan repair log #3

PCB Repair Logs, Repair Logs 6 Responses »

Feb 122016

Here is a picture showing a recently repaired Rastan PCB with the replaced chips highlighted in red.

rastan2-5

I will explain every step of the repair process here:

1) When powered up, the game was starting but was constantly rebooting after about 5 seconds. I checked the reset pin on the CPU but it was constantly high so that seemed not related to that. I checked the signals on the 2 CPU RAMs @ IC10 and IC22 (2x TMM2063 – 64kb) but nothing seemed suspicious. Anyway, piggybacking the one @ IC10 made the game not rebooting after 5 seconds but after a longer time. That was sufficient to let me think it may be faulty so I desoldered the RAM and it was tested bad on my programmer. Replacing it by a new one made the game working and not rebooting again and again. Good.

2) Well, the game was now playable but there was no FM sound (so no music at all), only voices were audible. Schematics are available online so I could see that the FM sound is generated by the YM2151 @ IC63 then it goes to an YM3012 DAC @ IC78 then it goes to a TL074 op amp @ IC100 to finally going to the MB3731 amplifier @ IC101. Outputs signals looked healthy at the outputs of the YM2151 and I had correct sound for the voices so the issue should be located before the mix between FM and voices signals, so before the amplifier: more probably within the DAC or the op amp. The TL074 is composed of 4 operational amplifiers:

rastan2-6

I noticed that every of the 4 output signals on the TL074 @ IC100 were looking weird with a negative voltage (between -1 and -2 V). There is another TL074 chip on the board that is related to the voices and every outputs showed a positive signal of approximately 2.5 V. That was suspicious so I desoldered the TL074 @ IC100 and replaced it by a new one and the FM sound was back ! (the signals on every 4 outputs were now showing a positive analogic signal of approximately 2.5 V).

3) and 4) Ok, so then the game was fully playable with perfect sound but there was some graphical glitches on a few items, as seen here in the attract mode:

rastan2-3

I have a previously repaired Rastan PCB that had one of its gfx mask roms replaced by an hacked 27C010 EPROM so, due to the nature of the problem here (glitches on only a few particular items), I suspected one or multiple MASK ROMs to be faulty. I started replacing these ROMs with the ones from my working Rastan PCB and got the gfx working perfectly after replacing B04-07 @ IC14 and B07-08 @ IC27. As noticed in my previous Rastan repair log, the gfx ROMs on this board are 128kb fitted into 28 pins chips. Finding blank chips with these exact specs is hard nowadays so I used 128kb 32 pins 27C010/27C1001 EPROMs as replacement (I could use a 27C1000/27C301 EPROM to make the modification even easier but I didn’t have one remaining then). To fit them on the 28 pins sockets present on the Rastan board, you have to make the following modifications on every EPROM:

If you use a 27C301 or 27C1000 non-JEDEC EPROM (simplest way):

Connect pins #30, 31, 32 together and connect them to pin #1 with a small wire.
Connect pin #2 to pin #16 with a small wire.

If you use a 27C010 or 27C1001 JEDEC EPROM:

Connect pins #30, 31, 32 together and connect them to pin #1 with a small wire.
Gently bend pin #24 so it won’t plug into the socket and connect it to pin #16 with a small wire.
Solder a small wire on pin #2 that you will plug into pin #22 of the socket.

I did these connections on the underside of the chip. Here is how it looks on my 27C010:

rastan2-2

And this is how it looks after the 2 chips plugged in:

rastan2-1

Now the gfx are fully restored, as well as the rest:

rastan2-4

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