Right now it's been confirmed there's no clk at the main Z80cpu, next i programmed the missing eproms, 2 were for graphics and 2 were for sound and sound samples, did a romident on all eproms including 3x bipolar proms.They all passed and have the correct data .
Looking in the schematics the clk is generated in the clk pcb and there's a 10136(ecl) chip at location 5L which outputs the divided clk frequencys .
This is fed to the input of another ecl chip 10125 at location 5J which was already replaced as it was rusty,scoped the output at pin 4 which goes to the counters at location 2b,2c,2d (pin2).
These counters generate the horizontal and vertical signals. Scoped all outputs on all three 74ls163 and were stuck high!
Replaced all 3 with new ls163's,powered on and .......
Ok,good news is we have clk at the cpu and I can see some Mario's scattered on the screen but game is not running code 🤔, data bus and address are active but not looking great. I've not connected my rgb invertor at the moment that's why the colours don't look right and the sound pcb is not connected.
There are 4xtms2532 eproms located at 5f,5g,5h,5k which hold the games programme data, I scoped the CE pin 20 and they were stuck high (not good),all of these bank of eproms CE are derived from a decoder chip ls138 At location 4h,inputs to this decoder looked ok but outputs were high.
Replaced this ls138 with a new one and powered on but still not booting, good news is CE is busy and working. Next I went to scope the work rams which are located close to the program roms at location 6h,6l,6j,6m,6k,6n .all inputs and outputs were busy and RW and CS pins were active, removed all 6x2114 srams and tested them on my pacman pcb,all passed ok except 2 which were bad.fitted new sockets and 6x2114 new srams,powered on ......
Oh yes
,game is running and I can coin and start but tile graphics Don't look right and there's no sprites?
To be continued...
Looking in the schematics the clk is generated in the clk pcb and there's a 10136(ecl) chip at location 5L which outputs the divided clk frequencys .
This is fed to the input of another ecl chip 10125 at location 5J which was already replaced as it was rusty,scoped the output at pin 4 which goes to the counters at location 2b,2c,2d (pin2).
These counters generate the horizontal and vertical signals. Scoped all outputs on all three 74ls163 and were stuck high!
Replaced all 3 with new ls163's,powered on and .......
Ok,good news is we have clk at the cpu and I can see some Mario's scattered on the screen but game is not running code 🤔, data bus and address are active but not looking great. I've not connected my rgb invertor at the moment that's why the colours don't look right and the sound pcb is not connected.
There are 4xtms2532 eproms located at 5f,5g,5h,5k which hold the games programme data, I scoped the CE pin 20 and they were stuck high (not good),all of these bank of eproms CE are derived from a decoder chip ls138 At location 4h,inputs to this decoder looked ok but outputs were high.
Replaced this ls138 with a new one and powered on but still not booting, good news is CE is busy and working. Next I went to scope the work rams which are located close to the program roms at location 6h,6l,6j,6m,6k,6n .all inputs and outputs were busy and RW and CS pins were active, removed all 6x2114 srams and tested them on my pacman pcb,all passed ok except 2 which were bad.fitted new sockets and 6x2114 new srams,powered on ......
Oh yes
,game is running and I can coin and start but tile graphics Don't look right and there's no sprites?To be continued...