Need S1985 and MB64h444 sony HB-F1 chips

By lovemsx

Resident (41)

lovemsx's picture

17-12-2010, 22:40

Hello I need the IC and the S1985 MB64h444 seem that burned ... where can I find? is hard?

Tank's
Taconi

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By sd_snatcher

Prophet (3204)

sd_snatcher's picture

18-12-2010, 00:44

The Yamaha S1985 is nearly impossible to find. But the Sony MB64H444 is even more hard to find than the S1985.

Are you really sure both of them are burned? If you really want to revive the machine, you'll need to resort to rebuilding their functions using discrete chips on a daughterboard. Here's the use of those chips on Sony Machines:

- S1985: YM2149 (PSG), Intel 82C55 (PPI), I/O address decoder, subslot controller, DRAM refresh
- MB64H444: MemoryMapper (not really used on your machine), SpeedController.

Probably you'll need to:

1) Replace the DRAMs with SRAM
2) Bypass the MB64H444 completely
3) Implement a daughterboard to replace the S1985 functions

If you ask me, that's too much trouble. Give yourself another MSX for christmas. :santa:

By lovemsx

Resident (41)

lovemsx's picture

18-12-2010, 01:24

my ic's vram is very hot... i go replace it.

By Leo

Paragon (1236)

Leo's picture

18-12-2010, 05:51

bas has s1985 , i got one from him
you should check more than just heat, check the 5v voltage

By lovemsx

Resident (41)

lovemsx's picture

18-12-2010, 09:15

hi
the 5v voltage is ok.
Let me explain what happened, was expanding to ram it, and dropped a piece of wire between the + 5v and +12 v, conclusion: the entire network has 12v 5v. why I think he burned some ic's. V9938 have been exchanged, and TTLS. I changed the settings, change the lack vrams. I'm waiting to reach the ic's. the memories of VRAM warm more than the Rams, and the chip heats mb64h444 not even a little, like a refrigerator hehe.

tanks