Thunder & Lightning repair log

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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

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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