Some questions in order to cure an A4000.

[arkpandora]

Hi,

I am currently jumping from one failing Amiga to another, hoping to bring it one of them to life without a technical intervention that would be beyond my competence.

The current one is an Amiga 4000 Desktop which used to belong to the same seller that sold me the A3000 I describe in another thread.  When I power it on, it only shows a black screen, while the power led either stays half-bright, or flashes for a few seconds before a reset that loops the process.  Sometimes (every minute or so), you hear a single click from the floppy drive.  I am of course unable to reach the startup screen.  The keyboard is responding : the power led answers the manual resets, and the Caps Lock key is operational.  I tested the computer without any Zorro card or hard drive : just with two different floppy drives successively.  I also removed the Fast Ram, removed then replaced the Chip RAM module, without success.

In order to identify the problem, I ask myself (and the Amiga.org community at the same time) a few questions.  At the moment I don't find any precise answer for them.

1. Can an A4000 work with without Fast RAM (only Chip RAM) ?  If so, can you confirm no jumper has to be changed ?

2. How do I know if a bare RAM module of the right dimensions, memory and speed will be suitable as Chip RAM ?

3. Can I use as Chip RAM a 4 Mb or 8 Mb RAM module (assuming the computer will only use 2 Mb) ?

4. Can an A4000 work without a hard drive (only a floppy drive) ?

5. Can you confirm that no hardware change (cable or jumper for example) is required in order to use a low density floppy drive instead of a high density drive as the only internal floppy drive ?

6. Without the IDE and floppy cables, what should the A4000's behaviour be at the switching on ?

Any answer to these questions is very welcome !

[arkpandora]

Thank you very much for your answer !

OK, my PC says that "FPM" means "Fantastic Plastic Machine", but I find out it is "Fast Page Mode".  How do I distinguish a FPM from a non-FPM module ?

I see there's a stain on the motherboard, that shades tracks.  Until now I have never cleaned a motherboard, so I have to add another question.  One would recommend isopropyl alcohol.  Being not more a chemist than an electronics specialist, can somebody tell me what this alcohol's specificity is for that use ?  Here I have denatured alcohol, whose exact nature I don't know : would it be convenient too, that is useful for such a cleaning and not agressive (if alcohol may be) towards the motherboard ?

Thank you again.