Hello,
I'm working at this drive out bootleg jamma pcb that has a corrupted image on some screens and it's totally messed up of black on others. I have another one working so I swapped the eprom am27c040 (number
which is causing the issue and also the 2 mc74hc273 on the left with it and the result is the same.
So I need to identify the ic that is failing.
I discovered that lefting the pin 18 the defect is disappearing on some screens (even if the background on others is totally missing) but the eprom gets really hot.
Besides checking the 2 rams on the left of the eprom what could I look at?
Thanks
I'm working at this drive out bootleg jamma pcb that has a corrupted image on some screens and it's totally messed up of black on others. I have another one working so I swapped the eprom am27c040 (number
which is causing the issue and also the 2 mc74hc273 on the left with it and the result is the same. So I need to identify the ic that is failing.
I discovered that lefting the pin 18 the defect is disappearing on some screens (even if the background on others is totally missing) but the eprom gets really hot.
Besides checking the 2 rams on the left of the eprom what could I look at?
Thanks
