Namco System 86 - Rolling Thunder, Sky Kid DX

PCB problems and fixes
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Magic Knight
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Namco System 86 - Rolling Thunder, Sky Kid DX

Post by Magic Knight »

For some time I've had problems with my Rolling Thunder board - often it wouldn't start, or would reset mid-game. I found that the custom chip '98' was a little loose, and poking or gently moving it would result in the game being ok, but obviously this was a bit of a nuisance.

Today, I was playing Sky Kid Deluxe, which uses the exact same hardware. It's a direct ROM swap + one custom chip between the two games. While playing a game, the machine suddenly went funny and crashed. It now won't start at all, just gives garbled graphics. It seems to be stuck resetting itself over and over. I thought it might be this same 98 chip, and poking it does sometimes make the game freeze completely.

I swapped all ROMs over and found that they are all fine, so the Sky Kid Deluxe ROMs are all ok. Rolling Thunder doesn't work on the Sky Kid DX board.

Now, while swapping the ROMs and poking about, the 98 chip on the Rolling Thunder board fell off completely. However, the game runs perfectly fine! It runs far better than it did with the chip on there. I found on the Internet that this chip is responsible for "lamp/coin output". Now, presumably this means it's got something to do with cabinets. So, if anyone knows, can they please confirm that this custom chip is probably not needed, and also, what they think I should try with my broken board.

Thanks in advance.
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trmatthe
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Re: Namco System 86 - Rolling Thunder, Sky Kid DX

Post by trmatthe »

Can you post a photo of the loose custom IC and any part numbers or text printed on it please? A photo of the board showing where the IC goes would be good for context too.

It's very rare that the manufacturers will add unnecessary ICs due to production and pick 'n' place costs, but is possible. Details on the chip will be invaluable in answering this though.

cheers
tim
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Magic Knight
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Re: Namco System 86 - Rolling Thunder, Sky Kid DX

Post by Magic Knight »

I swapped back the ROMs again to check if SKD would work without the chip and it did, so I pulled the loose one off its PCB, so the game gets further than before but still won't start.

I found the schematics for Rolling Thunder, this chip has a NOT Reset output, so it's possible that occasionally that line was being pulled low, resetting the game. This chip was used on older boards too, I've got one on both Toypop and Skykid. Rolling Thunder and these other System 86 boards were among the first JAMMA boards, so maybe it's part of a leftover design from pre-JAMMA days.

Here are the two chips. You can see how easily they can come off:
Image

Their position on the board, just in front of that other custom chip:
Image
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trmatthe
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Re: Namco System 86 - Rolling Thunder, Sky Kid DX

Post by trmatthe »

OK. I grabbed the Rolling Thunder schem and had a hunt around. Point 1E with CUS98 is in the top left corner of page 4. This is the snippet:
rolling_thunder-1e-cus98.PNG
The scan isn't too clear, but it looks like it outputs to the coin mechs, possibly acting as a coin lockout. It takes a /RESET signal and is linked to CUS60 @ 6A, possibly taking a couple of inputs from CUS60 to pins 12-14 of CUS98. CUS60 appears to generate the high order sound address lines. The scan is too poor to figure out entirely what it does, but it's certainly not a left-over component. Based on all of this I would have to advise reattaching it.

If you really don't want to reattach it, go to the sound test and compare the sounds to MAME. I suspect you'll be missing a few. I've also struggled to find out what Switch1 does, but it maybe the "screen advance" function in the video test mode.

cheers
tim
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Magic Knight
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Re: Namco System 86 - Rolling Thunder, Sky Kid DX

Post by Magic Knight »

Thanks for that. I've found the Gaplus schematics as well, it also uses this chip, and its schematics are much easier to read. The chip is connected to the coin counters, solenoid and lamp outputs on the edge connector. It takes input from the 56 custom chip, which is used for I/O. The switch is the reset switch input, which goes to the switch output. That seems to be everything. I've tested the sounds and they're all there. When I go to get it repaired I'll take it with me and explain it all to them. Hopefully it's nothing too serious. Just looks like it's continually resetting over and over.
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Re: Namco System 86 - Rolling Thunder, Sky Kid DX

Post by P-man »

If you remove the cus98 from a Pac-land, the game wont boot... that much i do know :)
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Re: Namco System 86 - Rolling Thunder, Sky Kid DX

Post by mastercello »

Rise from the grave - have a Rolling Thunder here with CUS98 missing, but it is booting - only it crashes sometimes and also Shows a weird error, the man char is falling down and dying below the Screen. :wtf:
Anybody any clue?
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