Amiga 3000/16mhz woes...

[Castellen]

Does the LED turn on and off when you press caps lock?  If so it indicates that there is some CPU activity.

Does the power LED change between 2 brightness levels just after power up?  This is in the computer's power up sequence.
Sounds like it's running through the power up sequence, so there could be a problem with the CPU itself, or any of the custom logic like Gary.

As suggested, reseat all socketed devices first.

One of the programable logic devices U202, U203, U701, U714 could also be faulty.

One of the small fuses could be open circuit if something has been plugged in incorrectly.


Could be any number of things really.  You're possibly a bit stuck without access to known working spare parts and some test equipment.

[Castellen]

@llwrath:

It's normal for U714 to get fairly warm.

If you're worried about it (they can fail) then you can get these wee self adhesive heatsinks for DIL package ICs, which could help.

These ICs are only used in the A3000, not in any other models (maybe in A2000???)
The good news is you can still buy the part.
The bad news is it's programmable logic.
The good news is I think I have the JEDEC files to program them somewhere... I think...
The bad news is you'll need a programmer, though I have one at work.

If you replace the PAL device with a GAL equivalent, they would probably run a bit more efficient, I.E. cooler.

I also have a few A3000 original spares too, including U714, in working condition.

[Castellen]

Forgot to add, could be a CPU problem with your A3000, hard to say.  To be honest, it could be any number of things.

Not sure if a CPU card will run without the onboard CPU running or not?  Never tried it.

If you have an spare A3630 or A3640 (rev 3.1), chuck it in and see what happens :-)


Other than that, it's time to break out the logic analyser and the digital storage scope!