VA0 + MX29F400

[theodor613]

Soldered the MX29F400 IC to the Dreamcast bios but it doesn't detect the chip. It detects the stock bios fine but the MX29F400 shows up as unknown, 5v and read only.

This was listed as a compatible IC for the 5v VA0 Dreamcast.

Edit: I see there is a slight difference in pinout. I'll make the adjustment when i get home.

Edit 2: Made the adjustments and it still doesn't detect the MX29F400. Checked all soldered point and everything is fine.

[SWAT]

MX29F400 not tested and it too small for stock BIOS firmware. It has 512 KB memory, but need 2 MB.
For VA0 you can use MX29F1610, it has 5V logic too.

[theodor613]

(26.07.2017 09:00)SWAT писал(а):  MX29F400 not tested and it too small for stock BIOS firmware. It has 512 KB memory, but need 2 MB.
For VA0 you can use MX29F1610, it has 5V logic too.

Thanks, now I know.

[theodor613]

Ok, so I ordered and received the MX29f1610. Have it in an adapter that wired to the Dreamcast bios ic. Now I am able to program and boot an MX29lv160 just fine with no problems. But the MX29f1610 did not detect still. After I added a 0.1uf capacitor between VCC and GND, the chip is detected and writes. But it writes very slow and it does not boot even though it says it writes complete. Put back the MX29lv160 and it writes and boots fine. Anyone have any suggestion or advice on how to proceed?

[SWAT]

You used DS from github? MX29f1610 fixed after release RC4.

[theodor613]

Yes. The chip detects and writes but slow, 2-3 minute writes time. It never boots. Sometimes a white screen and sometimes I can hear the animation sound. It never gets past that point.

[Gillbert]

You mentioned about a wired adapter, so are you using a SOP socket with extension wires? It may be a problem because of the length of the wires, especially for the address data.

I believe if you solder the MX chip directly on the ROM chip you won't get those problems anymore.

[theodor613]

(08.08.2017 18:17)Gillbert писал(а):  You mentioned about a wired adapter, so are you using a SOP socket with extension wires? It may be a problem because of the length of the wires, especially for the address data.

I believe if you solder the MX chip directly on the ROM chip you won't get those problems anymore.

Yes, i am using a SOP socket with extension wires. The length might be affecting the voltage. Even though with its' current length, the MX29LV160 works perfectly fine. I'll shorten the wires when I get home. The chips I got are blanks, I wanted to program them first then do a full bios ic replacement.

[Gillbert]

I see. Well, try to short the wires as much you can and get them organized, try to avoid cross-wired. Take a special attention for Vcc and GND lines. Good luck

[theodor613]

http://imgur.com/jEubytU

That's how long the wires are. even at half of its current length, it'll still be too long.

[megavolt85]

VA0 = 5V
MX29LV160 = 3V
MX29F1610 = 5V
long wire = resistance

VA0 + MX29LV10 + long wire = good
VA0 + MX29LV160 + long wire = bad
arithmetics is simple

[theodor613]

(08.08.2017 22:04)megavolt85 писал(а):  VA0 = 5V
MX29LV160 = 3V
MX29F1610 = 5V
long wire = resistance

VA0 + MX29LV10 + long wire = good
VA0 + MX29LV160 + long wire = bad
arithmetics is simple

i think i understand what you mean :

VA0 + MX29LV160 + long wire = good
VA0 + MX29F1610 + long wire = bad
Right?


Thanks guys!! it is now working and i now have my chips programmed for my VA0.