Stock A4000 040, full ram.

[Vlabguy1]

No boot up.  Screen flickers(no colors etc) briefly when power button is pushed, HD spools up but does not seem like it is getting asked to boot the OS.  Battery has been removed, before I got the machine,  no signs of MB damage from a leaky battery etc.  I see no activity from the floppy.  I insert a floppy, the usual click sound occurs but no data access activity.  Hold the two mouse buttons on power up and nothing.  Would a bad floppy drive boff the whole system from booting up?  Could it be a chip is not seated properly or in need of re-seating?

Any help, suggestions would be nice..

Thanks
Rich

[Vlabguy1]

Update:

Ug took the floppy drive out and installed in to a known working A4000 and voila the machine would not boot... I had no idea.  I also found a another issue, will post pics
soon.

[Vlabguy1]

Will it still not boot when you take the floppy drive out?

I tried taking the floppy drive out and still would not boot.  Makes sense because floppy is shot so even though it is plugged in cabled up .. no boot.  Could not even get to the early startup menu.  All know is my living room is now scattered with Amiga's.  I have not taken the processor card that was in non booting A4000 out to test that in another machine, but the problem seem to follow the bad floppy drive..

[Vlabguy1]

The Caps Lock light not changing after several presses doesn't necessarily mean any one thing. I had the same problem when I needed to reflow Alice's solder.
Compare the Amiga's boot flicker with that of an A1200. The monitor should lose sync momentarily, but it will be for about a tenth of a second. If the monitor just immediately resyncs without losing sync it may be the same problem as I had.
In my case because the joint was dodgy on Alice, it would occasionally boot up. Also leaving it on for a bit longer and then Ctrl-A-A would reboot it.

Do you have an oscilloscope? Check for activity on the SIMM sockets to make sure RAM is being accessed. If it's not, then the machine is probably waiting for one of the custom chips to respond correctly.

The machine should boot fine with just the PSU and the monitor connected, by the way. The keyboard is also useful but not necessary. You don't need the floppy connected.

Also, what is the voltage of the +5V line? It should be over 4.9V on an unloaded motherboard, though it may sink as low as 4.7V when everything is connected.

If you have an SMT rework station, I'd recommended a quick flux and reflow just to be sure. That's what fixed my A4000 (after years of trying to diagnose).

I will try some more testing when I get home. I found it strange though when I took the bad floppy drive out connected to a good working A4000 and it would not boot.  One thing is for sure the Floppy drive is bad.  And on the A4000 that is not working I found a pretty major issue when I removed the motherboard, I will post pics this afternoon.

Rich
ny
Oh ..to all those that suggest I get rid of the A4000 for an A2000.. well I have several 2000's so I am covered.  Thanks.

[Vlabguy1]

Why would a A4000 be so bad?

Anyway the click from the drive is caused by the OS asfair so the CPU is likely running and perhaps Paula/CIA. So checking the graphics related chips is a good idea. Btw, check power supply.

Do you have access to an oscilloscope?

The click I hear in the bad floppy drive is mechanical.  It's the metal disk protector sliding open.  I think I will take a known good floppy drive and put it in the A4000 that is not booting..

Rich

[Vlabguy1]

Added pics.. Enjoy!!

[Vlabguy1]

Just a hunch, but my years of repairing experience are telling me that the capacitor in the pic just may be a good place to start.

Agreed.  I found this after realizing the floppy drive was dead.  Took the whole machine apart.  Burned/melted through the plastic insulator and metal started to rust.  So it has been this way for quite sometime.  Not sure if this Cap is what did the floppy drive in.  Either way it needs work and I have some more testing to make sure this cap didn't do more damage ie the processor card etc.

Rich

[Vlabguy1]

Just a hunch, but my years of repairing experience are telling me that the capacitor in the pic just may be a good place to start.

**Update** Finally got around to pulling pieces from another A4000.  Turns out the
processor card(A3640) is bad.  Despite the fried cap the mother board works with a good
processor.  But Im sure that bad cap effects some functionality.  At least the MB isn't
completely shot.

Thanks all.

Rich