Help! Cannot get a4000 to boot!!! The humanity, etc etc

Erm, help? :)

I have an a4000 that I KNOW works (well it is refurbed - new caps etc) and was working perfectly until about 4 weeks ago when I stripped it down in preparation for tower installation.

Now that I have reassembled it I cannot get it to boot. I originally tried my Cyberstorm Mk III, but it would not boot, so I thought perhaps the Cyberstorm had gone to the big pinata party in the sky. So, to rule out the Cyberstorm, I tried an A3640 which I KNOW works - tried it in another system works fine, plus it is actually the a3640 that came from this problem system in the first place.

Still nothing. Now, when I originally removed the a4000 mb ram, I mixed them in with my collection of 72 pin simms (of which I literally have several dozen) - I know, that was stupid.

So, Im remembering that a4ks are VERY picky as to what they will accept in the chip ram socket.

By trying various simms I get various green screens, yellow screens, or simply grey blank screens.

Is there anything in particular I should be looking for? Does this sound like a chip ram problem? How many I's in Missississiisppis...ss..i?

Help!

A double sided 8mb Simm should work as Chip Ram (Will show as 2mb), have you got any of those? Give that a try without any other Ram and nothing else connected and see if you get a KS screen :)

Steve.

With no RAM in at all (including no chip RAM), you should get a green screen.

Get everything out apart from chip RAM and a CPU card. (Check int/ext jumper settings). You do not need a daughtercard in the 4000 for it to boot.

With the board I'm working on now, which was booting last time I put it away but was giving a completely black screen, I found that R79 had blown and gone open circuit... I got a black screen with that with chip RAM in, and green screen with no chipram. The LED would go from dim to bright showing it was doing something...

Check R79: it's under the motherboard at the CPU connector end. If it's good, you should get around 1.2kOhm across it even in circuit. If it's bad, your reading will be in the megaohm range.

Do bear in mind the wait which happens when the IDE interface is polled ;)

Thanks Chiark - will measure R79 now and report back...

---------- Post added at 20:50 ---------- Previous post was at 20:47 ----------

R79 = 1.23 k ohms.

All good.

---------- Post added at 20:51 ---------- Previous post was at 20:50 ----------

BTW - how long exactly IS the wait for the ide to be polled? I hear 30 seconds all the time, is that correct?

yep its 30 sec , an eternity when you problem solveing

Damn. it should be 1.2kOhm so that's spot on.

Jumpers set to EXT for the 3640?

Everything else removed?

Any LED activity?

Most important: does the power led go from dim to bright?
Kickstart 3.1 will wait AT LEAST 30 seconds with no HDD attached, I find that if no floppy is connected it will wait even longer. And indeed, if you are troubleshooting it feels like forever.

If your chipram is missing, start your search with criteria: double sided, many chips on each side. That should narrow it down. As pointed out, most double sided DIMM's will work as 2MB Chipram, but it's best if it's NOT EDO. I have even used a 32MB module when I couldn't find a 2. They are easier to come by :)

Oh, and it's 7. (the way you spelled it)

Hey guys, thanks for the help. I have a chip ram module (2mb fp double sided) coming.

When I power on, the power led goes from di (half bright) to bright.

From my limited guessing, the LED going dim then bright means kickstart is working, the processor is working, but there's a RAM problem... ;)

Hi Chiark,

yessum, I believe that is the correct assumption. Most of the simms I have to try are EDO, and the ones that are not are 16 mb or more. So I think it is a chip ram prob.

Interestingly, I got a couple of simms to boot to kickstart... for about 2 seconds before crashing - then they would not do it again, so I think it was just a fluke.

Will update when 2mb chip simm arrives.