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Sansui computer turntables

mootej

mootej

Active Member
Several of the high end Sansui turntables use a 4-bit microprocessor including the XR-Q7, XR-Q9, XR-Q11, XP-99 and a few others. I saw a few posts of failed processors in these turntables that meant the unit was scrap. The microprocessor was basically hard-programmed at the factory with the ROM hard-wired, so it not possible to use anything but the exact chip with the exact suffix code, generally unobtainium. A bunch of the old 80’s handheld video games used the same processors and some folks are downloading and dumping the Internal ROMs for these video games using an undocumented test mode for the chip and then setting up an emulation. They get the assembly code, basically the program for the device. I think it requires disconnecting the chip. This might be a possible solution to getting these dead turntables back in business. Once you have the program, a suitable current chip might be used to emulate the original chip.

So the final question, anybody dump the roms on any of these chips? I don’t yet have any of these turntables or ic chips but I think it would be a neat project.
 
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I haven't, though I own multiple XR-Q9 and 11, and an XP-99. The major problem with these is not usually the CPU but the auto tonearm mechanism. It is a ridiculously complex electromechanical design that fails with age. A fix for this was devised by forum member @Watthour a while back. I've yet to have time or patience to do the repairs on my own units here (the XP-99 works, the others don't) and all have the issue with the tonearm mech, the CPU's are fine.

Do you have a link for the process being used to dump the ROM? I assumed these NEC CPUs used a mask ROM and thus was inaccessible to be dumped, so I'm interested to see what trick they are using to do so.
 
https://github.com/lmiori92/ucom43-tools

That’s the first thing I found but I haven’t gone much further than buy a broken XP-99 which is being shipped. :-). Turns out the NEC ucom43 (qr-x5 x7 x9 x11) had a development chip that had an external rom. It had 63 pins but probably could be adapted over to the 28-pin mask ROM. Or probably something more current could be used if the assembly code was downloaded from a good chip.

but you’re right, probably mostly mechanical…

but still, I’d love to have the assembly code! If just to poke around. It looks like many of the later models all used the same masked cpu/prom. Not an NEC chip but a Fujitsu.
 
I do have a couple of NOS CPUs for the XR-Q9 and 11 set aside (purchased from Nies Ista's Sansui Parts shop in Holland years ago when it was still operatng). They would be good candidates for dumping the ROM, assuming such is technically possible. These seem to be pretty robust, and I've yet to personally see a failure of the CPU IC in the XR-Q and XP turntables. But if they can be dumped, I'm certainly in favor of doing so.

I have dumped and cloned ROMS in modules from my cars, various arcade ganes and various computer hardware. I store a large library of ROM images for devices I own and may need to repair in the future.
 
I’ll dig into that site a little more, build the downloader. There are some upd554c-118 mb8844-1145L and upd546c-107 on eBay for like $10 that could be used for practice…. No idea what they were originally used for …
 
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