Solved Wonderboy monsterland credit issue
- Thread starter jizzfu77
- Start date
check if you have 5volts on (O) and (P) parts side edge connector of the board,inputs are usually tied high.
if you have 5volts then press the coin button and it should go low.
if it goes low follow to the logic ic inputs which is usually a ls367 buffer or ls368,check the outputs of these logic chip.
cannot find schematics,also as you have changed the optoisolator check where it’s output goes.
if you have 5volts then press the coin button and it should go low.
if it goes low follow to the logic ic inputs which is usually a ls367 buffer or ls368,check the outputs of these logic chip.
cannot find schematics,also as you have changed the optoisolator check where it’s output goes.
Last edited:
thanks, if i am not wrong credits go to an ls257 (ic135). Schematics attached.
Hi, had a look at the schematics.
Are all your dipswitches off (sw2)?
I presume you have replaced ic54,there are 4 data bits which come out of ic154 and they goto the 8255 ppi chip from D0-D7 when you activate the credit switch, not sure which data bit is for credit?
Using a logic probe or scope look to see the data bits change when you press credit, if you see changes then i suspect the 8255 ppi.
Are all your dipswitches off (sw2)?
I presume you have replaced ic54,there are 4 data bits which come out of ic154 and they goto the 8255 ppi chip from D0-D7 when you activate the credit switch, not sure which data bit is for credit?
Using a logic probe or scope look to see the data bits change when you press credit, if you see changes then i suspect the 8255 ppi.
yup all sw are off, i changed the ic157 because the coin is on pin 15 on the connector, then go to ic157. I dont know if the 8255 is for credit or for coin meter, in my board the uln2003 is not present so no coin meter. I will check the D0-7 but if i push the credit button the signal goes low.
have you got a bootleg pcb or original?
inputs at the edge connector for system8 credits are O and P Parts side.
anyways if the outputs go from high to low on the opto you need to see if databits do-d7 change at the 8255 chip When you press credit switch.
inputs at the edge connector for system8 credits are O and P Parts side.
anyways if the outputs go from high to low on the opto you need to see if databits do-d7 change at the 8255 chip When you press credit switch.
checked d0-7 on the 8255 it has some actvity i think because are signals from the roms, nothing changes when i press the credit. On the opto i have the signal from high to low on INPUT, in output i have some activity and when i press the credit that activity lower by a bit (but not to zero).
Still the same, no changes when i press the credit button. The game works fine if in test mode (so no credit required) but you will start with all power up and 99 thunder.
NOTE: the opto pin 16 is connected to pin4 on the ic135 (74ls257), maybe i can try to check/change this one.
Last edited:
not visually broken, it gave values up to about half, beyond half it marked 0ohm.