"franken" MK1 T-unit resets (TL;DR WARNING)

mecha

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"franken" MK1 T-unit resets (TL;DR WARNING)

I can remove an item from my bucket list... sorta. before anyone chastises me for bidding on a semi-working MK1 T-unit board on ebay, know that I only got it for like $12.49.

if I'm understanding its description properly, the seller had a non-working MK T-unit board and I guess an MK2 board that didn't work right, and he swapped the MK roms over and generated a board that works perfectly fine until you get a Game Over. I compared the little ICs part #'s to the manual that came with it and found that the numbers matched... just in case it was like another Y-unit debacle I had a couple weeks ago.

the game's "problems" were listed as scores missing from the high score table and the character intros being messed up. my family previously owned a 5.0 T-unit back in '93-'95 and also did this, but as I came to discover, it's not the same symptoms.

I hooked the board up and played it sans-kick harness and got to endurance match #2, lost, and decided to pack it up, but I knew the above-mentioned symptoms (as I remembered them... I played a lot of MK1 back in the day...) would happen after a Game Over, so I watched it. and sure enough, the high score table was missing scores, but 5 of them, instead of the 3 I remembered. and after that the comic book offer page was solid black with a little trim of the background on the left side. and alas, the resets began.

the seller mentioned that a reset would clear the problem, so I hit the reset button. and it continued to reset, rug pattern looped over and over. so I powered the machine off, and waited. turned it back on, same shit. so I turned it off again and waited longer. this time it powered on and I got the CPU board test, which passes, and then the game resets on the "MIDWAY PRESENTS" screen. Test Mode didn't look any better, I got to the Diagnostics page and the game would freeze up and reset again.

after that I said piss on it.

so I have questions:

1) does the T-unit utilize a protection scheme like the Y-unit's 8-chip PAL, albeit in a different way?

2) if #1 is a NO, can I just drop swap this into an NBA Jam board and be on my merry way?

3) do I start scalping my existing MK2 and swapping roms to see if the problem goes away? :p

also, in case anyone was truly wondering, YOU CAN USE A MK1 Y-UNIT SOUND BOARD ON THE T-UNIT WITHOUT ANY CABLING MODS. (however, the manual outlines that there were different amplifier chips or something on the sound boards)
 
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Sounds like corrupted data on oone of the roms. Start reburning roms one by one.

would you happen to know if the video roms are the same between the different boardsets or do they actually have different checksums? I'd intended on reburning the game roms to run the T-unit Turbo Ninja with it. considering the sound roms were the same, I guess it's not entirely far-fetched. I didn't pop chips out to check for corrosion and shit like my MK2 had yet. might just have dirty chips too, who knows.

EDIT: well, I didn't take into consideration that the rom sockets are entirely different, so there goes that idea. I guess the game roms are a good place to start then lol
 
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I would suggest you just verify the chips against the dump. Will probably save you some time and in the event one is bad, will also identify it.

EDIT: well, I didn't take into consideration that the rom sockets are entirely different, so there goes that idea. I guess the game roms are a good place to start then lol

I don't understand this. The sockets are the same on all T Unit boards.
 
I'm not sure it will help, but here is a topic on the Y & T Unit boards, and here is a topic on possible T Unit security.

I made those threads. :D

I don't think the T-unit has security, the small ICs actually like... do something else. I'll have to compare to my MK2 and NBA Jam manuals I have saved, see if the numbers are identical.

one of the chips on my MK2 board matched, the other was missing the label, just saying.

the surface mount chip is the DMA controller, the TI processor is the rightmost socketed PLCC, and I'm not entirely sure what the 3rd chip does, but I'm leaning towards these all being the same. I found a couple part numbers for oscillators, whether those vary or not, I don't know.

we'll see.
 
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