GURU Boot issue when power cycling

[VirtualTed]

Hey guys,

I’ve been reading the boards for about a week now and I think it’s time for me to ask for a little help.

I’ve got an Amiga 600 (PAL, 1.5 JUNE BUG REV.) which likes to intermittently go to a black screen with a red-text  software GURU ERROR about 20% of the time when I cycle my power supply.  The sequence looks like this…
•   Power cycle
•   Power light comes on
•   Screen flashes
•   Guru Error (8000 0004, 8000 0003, 8000 000B, etc.)  The range of errors is pretty broad, but the first two come up most often.

However, when I CTRL-A-A then I never get an error.   In this case, the power light comes on, screen flashes, hard drive light comes on, then I get the classic insert disk screen.

I have tried using original Kickstart 2.05 and a Kickstart 3.1 with the same results.   I am also running these tests with nothing plugged into the motherboard.   The MB has been completely removed, and all I have plugged in is the video (composite) out and the power supply.   When testing the soft-reboot, I obviously have the keyboard plugged in.   So, just to be clear, no hard drive, disk drive, expansion, etc.

I’ve checked the front and back of the board and I see no corrosion with a magnifying glass.   The capacitors all look good to me.   I’ve also done a variety of tests with at least 4 different memory checkers to thoroughly test the chip ram.   No errors were found.   None of the chips seem hot to me although a few are somewhat warm.   I’ve re-seated the Kickstart chip about a half-dozen times with no noticeable difference.  Honestly, the board looks brand new compared to some of the others I've seen pictured.

The rate of failure on cycling the power can vary.   For a while it was closer to 50%.   Every time I power cycle, I wait 3-4 seconds – I’m not flipping it on/off quickly.

Finally, the keyboard Caps-Lock does not blink more than once whether it boots normally or errors.  So, it doesn't seem to be telling me anything.

I would appreciate ANY advice I can get as I have spent many late-night hours reading through the forums and trying to diagnose this.   I really want to get my Amiga to 100%!

THanks.

[VirtualTed]

Hey Mechy,

No chipram installed, not even the keyboard for my on/off testing which results in the guru error.  The board has not been re-capped - visibly they look great but I understand that this doesn't rule out a problem with the capacitors.  I was thinking of chasing that as a problem, but I'd be really disappointed if it came back and had the same issue.  So, I'm trying to rule everything else out first.

[VirtualTed]

Hmm.  I didn't really consider that it could be a PSU problem.  It SEEMS to be working well enough.  I don't have another to test with, but I might pop it open and see if there are any obvious issues.

[VirtualTed]

Well, I guess I will have to roll the dice and hope that this fixes the problem.  At $85 it's a pretty expensive gamble (I'd love to spend that on some other Amiga stuff).  

Anyway, I appreciate the advice and I'll update this thread on what the results are of the recap.

(And if anyone else has any other suggestions, I'll be keeping an eye on this thread in the meantime.)

Thanks guys.

-VT

[VirtualTed]

Well, I spent a bit of cash on getting the board recapped.  No improvement in the results I'm getting.  The A600 still intermittently starts with a GURU 8000 0003, 8000 0004, or something close to it (but mostly those two).

Soft-kicking it never results in an error.   Keyboard and RAM expansion are not plugged in - it's just the board.

Any other thoughts?  I will be receiving an A1200 soon and I'll check it with that PSU, but something tells me that won't be the issue.

-T

[VirtualTed]

Too bad. But at least you can rule that out. When you say power cycling you are talking about turning the switch off on the actual power supply yeah? Not at the wall socket?

Correct, I'm flipping the switch on the PSU, not the wall.   Doesn't seem to make a difference either way though.

[VirtualTed]

Thanks guys, very helpful and thoughtful posts and I do appreciate it.

I seem to have much better luck if I wait longer to switch the power on/off.  If I wait about 5 seconds, it seems to have the fail rate I mentioned in the first post.   If I wait a full 30 seconds, it seems to boot properly.  

I would think that 5 seconds is enough time to clear memory and "start over", but maybe not?   I haven't switched it on/off enough to make a decisive claim that this fixes the problem, but I have yet to see it fail if I wait 30 seconds to turn it back on and I think I've done it about 15-20 times now.

How long do you guys wait between power-cycling your Amigas?

-Ted

[VirtualTed]

Well, I guess I'll give it a shot with the new PSU.  I cracked it open once and it "looks" great in there, so I dunno.  Don't think I'll replace caps until I tried the other.

[VirtualTed]

Just thought I would update everyone on this, even though it's been a while maybe it will be helpful for someone else.

This problem continued to remain even after using another power supply.  Otherwise, the machine is perfectly fine.  I just have to wait longer to power-cycle it.  If anyone run across a solution, please keep me (and this thread) in mind, because even if I don't fix it, I would love to know what the real problem was and I'm sure someone out there may have something similar.

Thanks for all the help.

-T

[VirtualTed]

Gurus at power cycling are not uncommon - just make sure to give the machine enough time between flipping the switch off and then back on again. This used to happen with my dad's A2000 even back when it was "new" in 1990/91. Waited a few more seconds before power on and all was well.

Thanks Matt.   I think I'm coming to that realization.   The machine is perfect otherwise and I'm forgetting how these older devices need a little more time between flipping on/off the switch.