Total Carnage "Bad U99"

Hammerheadx

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I have two Total Carnage PCBs that come up with a "bad u99" error; one continues to boot up to garbled graphics but plays the attract mode, the other you hear the bootup "bong" repeatedly.
  • I have swapped out working U99's, no change
  • I have swapped out working U115s, no change
  • I have replaced the U115 single wipe sockets with double wipe, no change
Anything else I can try?
 
Not likely, I have complete TC and STV board sets that work correctly, so using those to debug what's wrong with these two.
 
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by Total Carnage the Williams Custom Chips should've been soldered in and I know from personal experience they're not overly pleasant to work on
 
I have two Total Carnage PCBs that come up with a "bad u99" error; one continues to boot up to garbled graphics but plays the attract mode, the other you hear the bootup "bong" repeatedly.
  • I have swapped out working U99's, no change
  • I have swapped out working U115s, no change
  • I have replaced the U115 single wipe sockets with double wipe, no change
Anything else I can try?
Bad PLD's can cause the false bad U99 error. (As the PLDs control mapping of the CPU reading the U99 and the U99 reading graphics data).
 
 
So not the security chip. The PLD at U53 which is involved in the graphics mapping of U99 to the graphics roms.

If you swap U53 from your Smash TV to TC what happens? I don't think it'll work - but I'm wondering if it will now be different - possibly reporting U99 good, but ROMs bad?

The Smash TV PLD is setup to map 3 sets of 4 ROMs 0x20000 bytes in length. Total Carnage needs the map of 3 sets of 4 at 0x40000 bytes in length. (And Mortal Kombat needs the map of 0x80000).

The only other game that has the 0x40000 ROMs is Super High Impact (not original High Impact) - if you can get access to one of them I'd be curious if swapping the U53 fixed your TC.

(So I know this because my SmashTV U53 failed, and I fixed it by using a Super High Impact PLD and burning new ROMs that fit the SHI mapping).
 
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