Need Sega 315-5308 chip to resurrect a Sega MegaTech PCB

[yavuzg]

Hello everyone,

I've been trying to repair a Sega Mega-Tech PCB. I've come to a conclusion that the "Mega Drive/Genesis" part of the PCB is not working.

What I've done so far;

- Board was not booting initially.
- Replaced the SONY port expander chips (CXD1095Q) - they were getting extremely hot.
- Replaced the faulty SRAM on the "Mega-Tech specific" region (The game selection menu Z80 region)

Now it boots, game selection menu on the second screen shows up but game cartridges do not show up on the list.

Checked the Z80 (on the MD region) and 68K. They just sit, no activity there. Replaced the SRAMs on the MD region with known good parts. Still no juice...

Then I've come to the conclusion that (basically nothing left to check) the Mega Drive/Genesis region is not working on this PCB. My prime suspect is the bus arbiter chip "Sega 315-5308".

I've opened up all my MD/Genesis consoles and I couldn't find this chip. I've read that this chip, along with the other special Sega customs used on this Mega-Tech PCB, resides in the following MD/Genesis models;

- Japanese Sega Mega Drive Model 1 with VA0 or VA1 PCB revision
- Sega Genesis Model 1 with VA2 or VA3 PCB revision.

I do have a VA3 rev Genesis but 315-5308 didn't show up there.

Anyway, if anybody has above consoles (or just the PCB or the chip), want to sell, please contact me...

cheers

 

[yavuzg]

nevermind...

found the console with these specisif chips. will let you know the results here hopefully with a brief repair log...

not too many mega-tech repair logs on the net anyway.

 

[stj]

resolder the original first,
it's a big problem with the stv boards.

 

[yavuzg]

resolder the original first,
it's a big problem with the stv boards.

Don't think the cracked solder is the problem on this board like the sh2 cpus on stv but I'll do that. you never know