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MSX2+ - Sony hbf1xd Upgrade

mbliss11

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Documenting my upgrade attempts of a Sony MSX HBF1XD to an MSX2+ capable machine. This involves replacing the vdp on the board with an upgraded version (9958) and replacing rom. There is also a latch upgrade that can be performed as well.

All chips came off the board smoothly and socket came in for the vdp yesterday. Put new chip in and a few bodge wires later and it works….kinda. MSX software that is supposed to detect an upgraded VDP does not appear to. Additionally software specifically made for the MSX2+ series looks….interesting….

Have a new VDP on order and will try it out hoping it’s just a bad chip and I didn’t Bork anything up. Pics attached. I am also on msx.org with a thread in there they don’t have capabilities of easily posting pics.
 

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Users on msx forum were saying they were getting similar behavior on a 9938. I scoped pin 21 out of socket which would have been composite video but was just getting solid 5v which suggests it’s not a 38. That would have been the first fake chip I have gotten. Who knows could still be fake but I am thinking it could just be faulty.

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Well - I am getting hit hard by the counterfeit chip market. Ordered 2 chips and both have been duds. The second just came in today….

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Comparison with the marginally working one:

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I am suspecting that the first chip I got was one maybe. Although I tried scoping its composite video pin out of socket and didn’t get a signal when it was on. Users on the MSX forum posted that they had similar screens running the software I did with a 9938 so it’s possible.

Yea I am learning the hard way how difficult it is to source :/
 
Funny; but now, the more scuff marks you see in the IC, the better. Fakes are usually sanded and repainted so they look new. Also, look for VDPs with the same marking style of the originals; but for sure, right now is hader than ever. A pity that there's not (yet) a pico9938/58 like the pico9918, really cool device
 
Funny; but now, the more scuff marks you see in the IC, the better. Fakes are usually sanded and repainted so they look new. Also, look for VDPs with the same marking style of the originals; but for sure, right now is hader than ever. A pity that there's not (yet) a pico9938/58 like the pico9918, really cool device
Yea this could create more of a demand for a modern alternative
 
Alright happy to report that chip just arrived and it’s real and works as it should :) attaching pic of seller info I got from eBay. I have one more chip coming in I am going to wait to test that one too before I closer the system back up

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Nice job! Even though you scoped the composite pin, I wonder if the resistances between pins on the bootleg chip are similar to the 9938.
Yea good question something I can explore more. The last chip that I ordered should be arriving sometime this week maybe I'll do some more probing with that marginally working one again.
 
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