Bad Video - Diagnostics?

[Rybags]

U3 = MMU - I would think you'd get very little function if it wasn't plugged in properly.

[1050]

Yeah, and pin 20 is 5 volt power so it wasn't doing a thing with any inputs to it. What I'm wondering about now is what does mattlacey have for voltage now that it's fixed? It was awful voltage, now I assume it's good - why? Several chips would be minus their chip select signals so maybe they were all latched up trying to talk at the same time? Interesting, I'll have to try this when I get one running again.

[mattlacey]

Yeah, and pin 20 is 5 volt power so it wasn't doing a thing with any inputs to it. What I'm wondering about now is what does mattlacey have for voltage now that it's fixed? It was awful voltage, now I assume it's good - why? Several chips would be minus their chip select signals so maybe they were all latched up trying to talk at the same time? Interesting, I'll have to try this when I get one running again.

 

Good call, I'll check it out tonight and report back. Prior to breaking out the scope and checking everything I'd tried pulling chips one at a time (did the majority of them before getting bored), powering it on each time and checking the drop. RAM chips seemed to cause a 0.02V difference, others were generally around 0.04-0.06V each, nothing seemed to make a huge difference in one hit.

 

Now it's up and running I'm trying to work out the best option for getting software running, carts are few and far between in Australia it seems

[BillC]

 

Good call, I'll check it out tonight and report back. Prior to breaking out the scope and checking everything I'd tried pulling chips one at a time (did the majority of them before getting bored), powering it on each time and checking the drop. RAM chips seemed to cause a 0.02V difference, others were generally around 0.04-0.06V each, nothing seemed to make a huge difference in one hit.

 

Now it's up and running I'm trying to work out the best option for getting software running, carts are few and far between in Australia it seems

If you don't have a floppy drive you could use an SIO2PC device to load disk based software from ATR images a PC, this is the least expensive method when there is a PC to use available. Alternatives are SIO2SD/Sdrive/SIDE2 or the variety of programmable cartridges available. Any of these options allows you to use software downloaded from websites.

 

The following FT232RL breakout board should work with the AspeQT drive emulator software, it only needs to be connected to 4 SIO signals.

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