Repairing MVS carts with 64mbit proms

[distropia]

Guys, some clarifications:

-The chips I've found are clean and new. Never programmed.

-They are the same brand and model SNK used in their carts.

-They are OTP (One Time Programmable), so once burned, you can NOT erase or change the data on them.

It would have no sense to buy used OTP chips, don't you think so?

Take a look at http://www.minato.co.jp/supinfo/M1882dlist_ver280_100820/dev_html/M1882dev/toshiba_dev.htm
Their programmer can burn the 64mbit toshiba, but unfortunately it is very expensive for me.

Xian Xi: imho I think a repaired cartridge this way should be 99% authentic, because SNK did repairs this way.

I always say I never give up... if you think about it, if anyone of us let a slightly damaged cartridge dies, as the time passes there would be less and less useful carts... that's not good at all!

 

[distropia]

Talking about the Shock Troopers cart...
Thanks to the point of kyuusaku, I reviewed (again) all the traces going from the NEO-273 to the C roms and all were fine.
Then I swapped the neo273 and VOILA, the cart came to life again!

I swapped the 2 and 24 pins on the S1 eprom (used a 27c010a) and now the letters appear correctly.

Finish

Now I have only 4 high meg count carts to repair! Lol

 

[Kyuusaku]

Good news about the fix. Are you fully sure the NEO-273 was bad? IC are so resilient the true fix is usually just reflowing a dry solder pad.

I'm still not convinced about the Toshiba chips, if it were programmable the TC53* designation would conflict with the rest of their mask ROM line (EPROM line is TC57*) so it's likely the couple programmers "supporting" them can only read them. It's probably good that you didn't buy them.

Edit: I Googled for mask ROM datasheets and Oki, Sanyo, NEC, Macronix etc all use 23/53 so that must be the Intel/JEDEC code.

 

[jew90]

Good news about the fix. Are you fully sure the NEO-273 was bad? IC are so resiliant the true fix is usually just reflowing a dry solder pad.

I'm still not convinced about the Toshiba chips, if it were programmable the TC53* designation would conflict with the rest of their mask ROM line (EPROM line is TC57*) so it's likely the couple programmers "supporting" them can only read them. It's probably good that you didn't buy them.

My programmer is a Minato device and supports this chip.

It cannot program it as far as im aware (I always thought this chip was a MASK rom and not programmable (even one time))

 

[distropia]

Kyuusaku: BOTH the neo-273 and the S1 chips was bad. First I checked every chip leg with a usb microscope, and then checked again continuity between the leg and the pad. No cold joints. No bent pins. All looked great and clean.
Probably some kind of shortcircuit in the mainboard broke both chips. Now I have to learn to build my own neo273, made of 4 x 74ls273 arranged in 2 pairs...

About the 64mbit toshibas, now I'm confused (I always thought they were OTP and also it would have no sense to sell mask roms if they're no-programmable at all). To solve this, I've asked eight chinese vendors to provide me the datasheet and some photo of the actual chip they have. For me it was impossible to find the d*** datasheet (maybe 'cos being a mask rom?), but well... let's try them.
Also asked for any 42pin 64mbit in DIP format they could have.


EDIT:
Almost a month after that, and no response from that vendors. Nothing.
So it seems to definitely be Mask Roms, as you said, with no datasheet and no compatible 42pin DIP equivalent. I'll try the SMT chip + pcb adapter to 42pin.
I'm still guessing what mask roms those vendors have in stock... and what code in them......

 

[pier]

Kyuusaku: BOTH the neo-273 and the S1 chips was bad. First I checked every chip leg with a usb microscope, and then checked again continuity between the leg and the pad. No cold joints. No bent pins. All looked great and clean.
Probably some kind of shortcircuit in the mainboard broke both chips. Now I have to learn to build my own neo273, made of 4 x 74ls273 arranged in 2 pairs...

About the 64mbit toshibas, now I'm confused (I always thought they were OTP and also it would have no sense to sell mask roms if they're no-programmable at all). To solve this, I've asked eight chinese vendors to provide me the datasheet and some photo of the actual chip they have. For me it was impossible to find the d*** datasheet (maybe 'cos being a mask rom?), but well... let's try them.
Also asked for any 42pin 64mbit in DIP format they could have.


EDIT:
Almost a month after that, and no response from that vendors. Nothing.
So it seems to definitely be Mask Roms, as you said, with no datasheet and no compatible 42pin DIP equivalent. I'll try the SMT chip + pcb adapter to 42pin.
I'm still guessing what mask roms those vendors have in stock... and what code in them......

can you explain us how did you succeded to repair this cart?

 

[shadowkn55]

Using this.

http://www.neo-geo.com/forums/showthread.php?277452-64Mbit-(8MB)-flash-adapter-board

 

[NexusX]

can you explain us how did you succeded to repair this cart?

Used that to repair a Mark of the Wolves cart a while ago. There is a thread about the repair on here somewhere with pics. They work well. There are a few pros and cons though.

 

[pier]

i hope that one of the pros is that i can use tl866 plus with the 16bit eprom adapter to do it.

EDIT: i definitely want to learn that and try to repair it.