Usually if there is a missing clock on the main CPU of a PCB it's pretty easy to track back to the crystal and it's associated circuitry but on this bootleg Argus it's been a long search following traces and since there's no schematics and not much info about this boardset I'm putting this here in case anyone else has to try and sort this issue.
Hopefully the original boardset will be similar to this.
So the CPU clock was stuck high on this game. There are two crystals,one on the sound section next to the main CPU section and one on the bottom board which I assume is graphics. Both appeared to be working but I had no way of knowing which crystal provided the clock for the main CPU,The sound CPU was getting clock so I had to trace backwards from pin 6 of the Z80.
The first chip it comes from is IC44 near the CPU. It's an LS367 hex buffer and the clock comes from pin 13 so it's fed from pin 14.
That pin this goes through the connector to the bottom PCB. Took a while to trace but it come from IC128 which is an LS32 so I had two inputs to trace. one pin had activity but the other one was stuck so following that one led to IC221 which is an LS08. One input was held high since it was connected to +5V so I followed the other which was still stuck and that led to IC184. This was a fujitsu LS04 pin 6 and pin 5 was of course active.
A quick piggyback and the game was finally running.
Never come across a CPU clock following such a convoluted course before and I haven't even traced it back to it's source yet but since I now have clock it's good enough for me.
Looks like I'm going to have to fix some graphics issues but I bet that's going to be down to fujitus as well. There are a few LS04's so they will be my initial suspects.
Hopefully the original boardset will be similar to this.
So the CPU clock was stuck high on this game. There are two crystals,one on the sound section next to the main CPU section and one on the bottom board which I assume is graphics. Both appeared to be working but I had no way of knowing which crystal provided the clock for the main CPU,The sound CPU was getting clock so I had to trace backwards from pin 6 of the Z80.
The first chip it comes from is IC44 near the CPU. It's an LS367 hex buffer and the clock comes from pin 13 so it's fed from pin 14.
That pin this goes through the connector to the bottom PCB. Took a while to trace but it come from IC128 which is an LS32 so I had two inputs to trace. one pin had activity but the other one was stuck so following that one led to IC221 which is an LS08. One input was held high since it was connected to +5V so I followed the other which was still stuck and that led to IC184. This was a fujitsu LS04 pin 6 and pin 5 was of course active.
A quick piggyback and the game was finally running.
Never come across a CPU clock following such a convoluted course before and I haven't even traced it back to it's source yet but since I now have clock it's good enough for me.
Looks like I'm going to have to fix some graphics issues but I bet that's going to be down to fujitus as well. There are a few LS04's so they will be my initial suspects.