Jul 222018
 

I’ve been sent from Portugal a box of faulty PCBs for repair with some Toaplan stuff inside like Vimana and Out Zone (both japanese revision)

Vimana :

Board was booting and played fine except for some little glitches on background:

Backgrounds data are stored in four 28 pin 1Mbit MASK ROMs:

Devices were dumped fine except the one @ROM3 which gave inconsistent readings.Loading the file into MAME emulator reproduced the issue exactly:

I replaced the faulty MASK rom with a 32 pin 1Mbit non-JEDEC EPROM (adding the missing sockets)

Board 100% fixed:

 

Out Zone :

Board booted but sprites were garbled :

Probing a row of RAMs revealed /CE pins on three of them  (the two 6264 @13A-14A and the 6116 @16A) were receiving no signals :

At a closer inspection I found a burnt trace going under them:

I removed two of the three involved RAMs:

Tracing back the burnt trace I figured out it was a GROUND signal that should have been daisy-chained to the /CE lines (grounding also address lines A10-A9-A8 of the 6116)  of the three RAMs enabling the chips.A couple of jumper wires did the job:

 

 Posted by at 10:24 am