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Hit a dead end, SWC DX issue, any ideas?

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Joined: 02 Oct 2008
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PostPosted: Thu Aug 23, 2018 1:03 am    Post subject: Hit a dead end, SWC DX issue, any ideas? Reply with quote

I have a SWC DX 32M model, it is a later model unit, SN in the 20k's, and has the newer FC9304 ASIC. The issue is that sometimes it will boot up glitchy graphics (you cant even make out anything), but 99% of the time it boots a blank/black screen.

The first obvious step was checking CIC, but it is not a CIC issue, I have tried both the cart bypass, and swapping to a working CIC chip from an early production DX2 I have and that does not resolve it, and this chip works fine in the DX2 on my US SNES. Both CIC chips are 10198S, NTSC chips.

Next I checked the SRAM, since it appears if you remove it the system will boot blank (tested on my DX2), swapping between the units the DX chip works fine in the DX2, but not the other way around.

The programmable logic gates are appropriately board specific and do not appear to be able to be swapped between boards unless someone knows more about the way they are setup on the DX/DX2 units (though oddly there are faint markings on the DX2 chips for the positions on the DX board, 8 and 9 on DX vs 6 and 7 on the DX2). I have seen configuration files for the earlier SWC models, but none for either of the DX models.

the last ditch effort was trying out a swap of the EPROM, since the board layouts are very close (yea, I know, not a horse shoe or a hand grenade), but I figured it may be able to load up something. And my inclinations were correct, the DX eprom loaded on the DX2 HW (it throws an error, but you can navigate the menu), so it looks like there is a valid bios on there, the 1/4/96 one. The DX2 eprom did not load on the DX HW.

So, long winded post aside, has anyone heard of issues with the ASICs going bad in these units, specifically the FC9304 ones (originally the DX would have had a FC9203)? As that seems to be the one part that I would suspect at this point. Most of the other chips are for the FD controller, or IO buffering, which I could check but are less likely to be causing the display issue.

Any input would be appreciated since I have hit the point where the board is scrap if that IC is the bad one, most other chips would have some method of replacement, but that one would have to be pulled off another working board, and I have no desire to do that.

I can post some pictures if any are needed, but I have went over the board a number of times and there are no broken traces, solder shorts, or the like.. There is just a corner corroded by those darn batteries, but that was cleaned and inspected and did not compromise any traces to the point of failure.
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