myPinballs
Active member
I picked up a reasonable condition SCI Chase HQ pcb to hopefully* use in my chase hq cabinet. It was sold as non working so I cam attempting to fix it up. This version is the one I like more as I think I played this most in theacrades, back in the day. I remember the 'robo-cop' van chase scene as my favourite with the guys shooting at you from the back of the van as you get close etc. Classic 'detroit' haha Anyway, onto the fix attempts.
Currently just a black screen knightmare!!! Top board is ok, not perfect, does look like some traces are a bit tarnished but buzz test ok so far. Under close inspection they look ok. Bottom board looks nice & new.
To start with I checked the following . cpu clock ok, reset chip ok (with higher current 5v supply), reset line to main cpu watch-dogging, all main game roms check sum ok, changed all 3 pals near the main cpu, no difference. There is data on the 68000 for little but then stops with the reset watchdog
I am using the chase hq 1 schematics and they are ok, but things don't match exactly. On SCI we are using the terrible TC0220IOC instead of another suitably terrible one. I really have no idea why you would make a custom chip for I/O and not have some sort of protection for bad connections built into it. Anyway I checked and the reset line output for the main 68000 is indeed fed from the TC0220IOC and the TC0220IOC seems to take the VBL clock and the normal reset line in from the normal reset chip to make the custom reset line output.
So I decided to remove the TC0220IOC and temporarily jumper the normal reset line to the 68000 and see what happens.
Still a blank screen but now I can see data and address on the main 68000 and main roms. I was kind of hoping the game might boot alittle way and do a ram test etc, but I guess Taito have some sort of check/initialise to the TC0220IOC first to see if its ok before anything is outputted on screen, STUPID!!!
So my next thing will be to change this chip, remove the temp jumper and see if I get any video output. I see another thread on here about this TC0220IOC and maybe a group buy so will check that out.
Currently just a black screen knightmare!!! Top board is ok, not perfect, does look like some traces are a bit tarnished but buzz test ok so far. Under close inspection they look ok. Bottom board looks nice & new.
To start with I checked the following . cpu clock ok, reset chip ok (with higher current 5v supply), reset line to main cpu watch-dogging, all main game roms check sum ok, changed all 3 pals near the main cpu, no difference. There is data on the 68000 for little but then stops with the reset watchdog
I am using the chase hq 1 schematics and they are ok, but things don't match exactly. On SCI we are using the terrible TC0220IOC instead of another suitably terrible one. I really have no idea why you would make a custom chip for I/O and not have some sort of protection for bad connections built into it. Anyway I checked and the reset line output for the main 68000 is indeed fed from the TC0220IOC and the TC0220IOC seems to take the VBL clock and the normal reset line in from the normal reset chip to make the custom reset line output.
So I decided to remove the TC0220IOC and temporarily jumper the normal reset line to the 68000 and see what happens.
Still a blank screen but now I can see data and address on the main 68000 and main roms. I was kind of hoping the game might boot alittle way and do a ram test etc, but I guess Taito have some sort of check/initialise to the TC0220IOC first to see if its ok before anything is outputted on screen, STUPID!!!
So my next thing will be to change this chip, remove the temp jumper and see if I get any video output. I see another thread on here about this TC0220IOC and maybe a group buy so will check that out.
