Repair Diary #4 - Simpsons (Work in Progress)

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    • xodaraP wrote:

      I've actually found Fujitsu SRAM to be really reliable. Especially the slim 6264s (MB8464 in Fujitsu numbering)

      Their logic ICs are rubbish though.

      Sony is the brand of SRAM I am always having issues with. I've repaired at least half a dozen MVS boards alone with bad colour RAM, and it's always Sony.
      I wish they were just that :D
      Believe me or not i have a wall mostly covered by bad Fujitsu TTLS...
      Worst of them are flip flop and or/and, those are the most ones i always find with floating/bad outputs
    • I have just got a Simpsons board with almost exactly the same fault as yours. Thought I'd see if you got any further with it

      If you haven't done the internal mask ROM test already (not the boot test, but the test in the service menu)

      I'd be interested to know what yours reads. Mine reads all sprite mask ROMs as bad (which knowing Konami boards is entirely possible) - I'm also going to reflow the 2 customs and see if that improves anything.

      I've ordered enough 27C800 EPROMs to replace them all if they are in fact all bad.

      Edit: I reflowed the sprite customs and it didn't have any effect

      The post was edited 1 time, last by xodaraP ().

    • My board has been sitting in the To Do pile since I started grad school unfortunately. I graduate in two months and it'll be great to get back to all of my projects again.

      I think pulling and testing the mask ROMs is a good idea. I've worked on several other Konami boards since I acquired that Simpsons boards and faulty mask ROMs is a common Konami symptom it seems.
    • Indeed. On mine after running the test all my 27C800 compatible mask ROMs have failed (4 graphics and one sound) the other 3 read ok though.

      I've ordered enough to cover them as well as sockets and they'll be here in a couple of weeks

      Good news on your upcoming graduation - what's your new qualification in?
    • It's possible the custom is bad and that's why it's reading them all as bad. But I did notice on those with bad customs they tend to have other issues than just sprites all over the place so hopefully it's not that. The other thing I noticed is that every time I run the ROM check, it comes back with a different bad checksum - so I think the ROMs are genuinely bad. Also the fact that all 5 are the same type suggests it's probably the case.

      Sucks that so many are bad, but as you said hopefully that gets it back up and running (desoldering 210 solder joints is in no way shape or form going to be fun though - not looking forward to that at all)

      Even if the custom does turn out to be the culprit, I'd still prefer to have all the mask ROMs socketed since now or later, they most likely will fail.

      If it does fix it, I'll let you know - I suspect that yours has the same issue as whatever mine is given just how similar the fault is (though I don't think all your mask ROMs are bad - other than the title screen yours is definitely better than mine)