After some successes doing minor board work on Williams, Bally, Gottlieb system 80 and Game plan, I thought I could handle rebuilding the system 3 mpu in my freebie "Disco Fever" which was booting into audit mode with battery rot issues. Replaced all the Scanbe sockets, relocated game ROM, cut and jumped the chip select circuit, burned a 2716 (which may not work, I haven't burned a good ROM yet) added socket and NVRAM in place of 5101, ohmmeter said it was good and it looked decent. Only lifted one pad which wasn't t connected to a trace.. Eagerly put the boards back in and.... Two LEDs lit, no flicker. Tried it without driver board, same. Back to the bench. Hooked up power 5v & 12v, hit switch and LEDs blink twice... Weird. Start buzzing around with logic probe and notice flipper ROMs are HOT! Power off. Power it back up, nothing . back in game, nothing, dead. Sending it out to a pro is no longer an option, crossed the Rubicon already with a "hack".... And Disco Fever is hardly worth a $325 Rottendog board. So it looks like Firepower sitting next to it is getting some displays, my parts bin is getting bigger, and EBAY is getting some more listings. And I'm gaining experience the hard way this time. Ouch.

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Oh, and my apologies for the photography looking like it was done by Bob Guccione.

Better shots

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Power connections, yellow is 5v

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Select modification. .

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I don't dare order up a proper set of roms for it if it's just gonna fry em. This one's on the bubble right now..

I would absolutely love to do that Hans!, I really would like to keep this game running, cheesy as it is. The trace is cut too... so the single ROM adapter, does that replace the flipper roms as well as the game rom? I have an old EPROM burner here, as well as a UV eraser, but haven't yet been able to produce a working chip. The software verify the chip fine but never had one that actually works in a game.

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Thanks soooo much, PM sent.

Holy schnikes, I just looked at the power connections in that pic above and although I stated "yellow is 5v" I'm pretty sure its 12. Now what did I fry?

Good news is the new NVRAM survived, tested it in another game and it still worked. (you make em tough I guess!) The reset section still works, ROMS are now irrelevant since I have Hans' ROM adapter now with a single chip for everything. Guess next is to inventory what I have around here for chips or grab a random board off Fleabay and start over...

Can't believe I did such a bone head move... doh!

I ordered a set of standard flippers for mine in case i didnt like the banana flippers.

Just a progress report. I purchased an allegedly working system 3 board off Fleabay and as a typical Fleabay board, it doesn't. .. so I'm back to square one. But at least I'm back to square one! Both leds come on and stay on which is more than the one I fried does.so now I really need to figure out my EPROM burner and try to get Leon's test rom. Or throw in the towel and order the reconditioned 3-4 board from K's Arcade for $160, which I probably should have done in the first place but then I would have learned nothing.

Forgot to add, I did buzz around the CPU chip (installed in Hans' ROM adapter) and the CPU is running.I'm seeing good pulse activity at all the address and data lines there.

Update. Finally found some time to give DF some attention. The Ebay board was different from my original in that many more chips were socketed. All Scanbe, yay! So I heated up the irons Monday and replaced the CPU, PIA, RAM, ROM and a few other sockets. There's one Scanbe socket left because I didn't have a 16 pin DIP socket for the bottom right. IC (forget the number) powered it up with Leon's test ROM at ic17 and the LEDs began blinking in unison. Good! Now were getting somewhere. Good pulse activity around CPU and pia outputs. Put Hans' adapter board and ROM back in and both LEDs lock on, no flash. With test ROM in and adapter with ROM it flashes both. Memory test with NVRAM installed flashes one then the other then resumes normal flashing . I'm thinking there's something I'm missing that should be obvious. Like a jumper change for the new ROM adapter or something.. I am making progress but it isn't giving up easily.

Oh, and forgot to add, 200 desolder/solder connections on 7 or 8 chip sockets and not a single lifted trace!

Thanks Hans, I did remove the original ROMS and only replaced the socket in IC17 to use the test ROM in it. I may replace a couple more sockets in that row and try some replacement EPROMs as another test.

More progress, new problems. I finally got it to boot. After replacing the ROM sockets and new EPROMs it no longer boots into audits, but it doesn't boot into game over either. The displays look normal, all zeroes, but there's no attract mode and it won't coin up. So, limbo mode. 40-pin interconnect ? I think i'm done with the MPU aside from replacing header pins, I suspect the trouble lies in the driver board or interconnect.

This morning I decided to have some pinball with my coffee. Then I figured on buzzing around the PIA chops on the driver board on Disco Fever. Accidentally bridged a couple pins on the PIA on the rh side of the driver , pins 21&22 I think. All hell broke loose, blew the 28v fuse, both leds on the mpu came on, displays went fuzzy and dim OH NO! Turned the game off and back on went into audits. Aaaagh! Turned it off and on again.... attract mode!, hit the coin switch, credits! Hit start, and..... BOOGIE TIME!

All the new bulbs, rubbers, wax, etc. Is done, played all day off and on, this game is saved! Thanks to Hans and everyone else for their expertise and help!