looking at the top left of the pcb is the sound section,there are 2x eproms labeled DG7/DG8 which more likely hold the data for the music and sound samples.
I did a romident so that to rule them as the culprit,all passed ok.
Scoped the sound cpu(z80) and there was normal activity,next i checked the DAC output (circled in red).
so looking at the pinout of this DAC(YM3014) the analogue output comes out on pin 2(Tobuff).
On my scope it showed no output(0v),all other pins looked ok until i got to pin 4(digital i/p).
Now that dont look correct 😟,i should be getting a TTL reading of 5v digital signal but i get 1.6V? this explains why i am not getting a analogue output from the dac.
Next i look at the music synthesiser chip YM3812,here is the pinout.
So pin 21 squirts out the digital signal and this goes to feed pin 4 of the ym3014 dac,decided to remove this Ym3812 and put in a new socket.
Luckily i had a couple of these chips in my part drawer.
Ok now lets fire it up 🤞....................
Ooooooooo yes
Music is back!
Played the game for a while and all is good,another one is saved.If anyone is interested in buying this game send me a PM.
I did a romident so that to rule them as the culprit,all passed ok.
Scoped the sound cpu(z80) and there was normal activity,next i checked the DAC output (circled in red).
so looking at the pinout of this DAC(YM3014) the analogue output comes out on pin 2(Tobuff).
On my scope it showed no output(0v),all other pins looked ok until i got to pin 4(digital i/p).
Now that dont look correct 😟,i should be getting a TTL reading of 5v digital signal but i get 1.6V? this explains why i am not getting a analogue output from the dac.
Next i look at the music synthesiser chip YM3812,here is the pinout.
So pin 21 squirts out the digital signal and this goes to feed pin 4 of the ym3014 dac,decided to remove this Ym3812 and put in a new socket.
Luckily i had a couple of these chips in my part drawer.
Ok now lets fire it up 🤞....................
Ooooooooo yes
Music is back!Played the game for a while and all is good,another one is saved.If anyone is interested in buying this game send me a PM.
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