Amiga 500 intermittently reboots for no reason!

[meega]

The major risk to a disk is if the machine is actively writing to it (not just reading) when it resets or loses power. That can corrupt the data on the disk, which is why you should never use the original disks as anything other than sources to clone for everyday use. Recovering data from a corrupted disk can be done, with varying degrees of success. Diskdoctor might manage it. Transfer anything you do manage to recover onto a fresh disk. If a disk is corrupt, a reformat will normally allow you to carry on using it. As long as there are no hard errors, it should take and hold a format.

When ejecting a disk, make sure it comes out swiftly and smoothly - sometimes your finger can slip, and the thing gets stuck halfway or pops back in... again there is a risk of physical damage to the floppy surface, but it is quite a slight risk. A good firm press on the button should make the drive eject cleanly. Amiga floppies are amazingly durable, and you should experience few problems. Do beware of hairs trapped in the mechanisms (pet owners), and try to avoid very dusty atmospheres with fans blowing dirt onto the machine.

Ed: as you are in Oz, look out for spiders. :-)

[circlip]

@meega... hmmm... what to do with my cats? :crazy: We don't have A/C in our house, so fans are the buzz at our place, we have them in each room, gets pretty hot this time of year. I remember using one of them for my old C64 PSU, i think they all(??) have overheating problems, well my two C64 PSU's did anyways.

Man, Amiga disk drives are funny aren't they? They should've put a seperate LED for "write floppy" so we know when to be careful around it. :roll:

Edit: euch! spiders, little baby {bleep}roaches... kitty cats, at least we have no snakes in the city! :-)

[meega]

Just don't kill the power, press eject, or reboot when the disk is spinning - if it's working at all then let it finish.

Ed: except of course you are allowed to reboot if you know for a fact that it is only reading and not writing.

[rkauer]

 Just some tips:

 Last series of A500 have the amber LED for floppy and green for power.

 When you open your Amiga again, look for the circuit-printed label (near the expansion RAM header). There you will see the model of the motherboard.

 It must says some like:

 " B52/Rock Lobster (yeah, is the song from B52'S)

   the initials from the crew who made the board

   A500 REV. X.xx ( <- expect for 6 or 6A here)"

------

 For the rebooting issue: with the Amiga opened and not powered on, look for the keyboard header, see if it is properly connected and even further, if the cables are not loosing or peeled. If so, insulate them (one by one).

 The keyboard "cpu" is in the keyboard board. If a problem arise in the unit, the capslock LED will blink a number of times.
 
 If apparently everything is OK, close the Amiga case and go for the next, who is...

------

 The PSU

 Whit it disconnected from the mains and from the Amiga itself, open the brick (four phillips screws). You'll not zapped or anything, just be sure to await half an hour after disconnected from the mains.

 Check for bulking or leaking capacitors. If you spot one, swap it for an identical unit (the values are printed in the capacitor itself).

------

 Hope it helps!

[TjLaZer]

Have you tried running the 500 WITHOUT the keyboard plugged in?  (The actual thing you type on, not the computer itself!)  Yes you can run the Amiga without the keyboard plugged in.  Test to see if it does it's reboot thing...  You can buy a keyboard for CHEAP,  Just bought one NEW for $10 last month.

[orange]

@TjLaZer
hmmm, where did you get it NEW? I'm interested..

I also think he should disconnect the keyboard.
By isolating the keyboard, I mean putting some paper or plastic between keyboard controller and metal shield edge underneath it.

Have a look at it by (easily) removing the 512Kb cover on bottom of Amiga 500, you don't have to unscrew anything for that.
You'll see plastic insulator, make it thicker.

PS. orange is my nick  ;-)

[TjLaZer]

Where else, eBay!  They are on there all the time.

[circlip]

Hi all... sorry @ orange for nick mix up. I just saw "Defender of Faith" and automatically took it for your nick for some odd reason.

Anyways, I'm going to crack open the A500 unit again, and see what the go is.

I'll try the "no keyboard" trick too, and PSU after 1/2 hour of off time. Only problem is that sometimes it won't play up as it should (like last time) so I'll have to check back a few times to see if everything definately is ok. I'll try gently pushing a few chips again too.

Ebay is one of my sources for stuff too TjLaZer, I saw an A520 modulator, new in the box and plastic wrapping! :-o

[circlip]

@ rkauer

It is written on the mobo this:

B52 / ROCK LOBSTER
GRR/I3P/GUAY/FISH
RVW/VFA/DCA
HJM/CJW/TC/SMK
GET/LLK

A500 REV 5

btw, what is a keyboard header? Is it the plug? (sbsolute newbie here.)

[TjLaZer]

Header = pins sticking up from PCB.

[circlip]

So I've checked the keyboard header... seems fine. The wires are ok too... I might put more insulation on under the keyboard pcb someday.

So, one question about the "flashing" Caps Lock key... does it mean it really COULD be the keyboard being the problem? It flashes constantly, no real pattern to it, just on-off-on-off really quickly.

I tried disconnecting the keyboard, and it hasn't reset itself in a while. I tried plugging it back in, and it reset itself constantly at 1 second intervals. Unplugged it again.. nothing. Plugged in again, didn't seem to reset again either.. so I'm thinking probably a broke keyboard. There is a cheap keyboard or two on ebay... should I give it a shot?

Circlip.

ED: meega, I found a little yellow sticker that fell out when I opened the A500 up again. it said "A500 P" and then a serial number. What's the difference between an A500 and A500+ ?

[orange]

er, I think you really should NOT (un)plug keyboard while Amiga is ON, you could damage something.
IIRC the flashing capslock usually is an error code: number of blinks indicate the type of problem (for eg. two lines are short).
But not in this case, if its flashing very quickly.

If you got time and patience, its worth opening the keyboard (all those tiny screws) and checking if something like cocacola has damaged it.

[DrDekker]

Just remembered - I once had an A500 (a very long time ago) that had the same problem.

It took me quite a time to find the cause.

The problem ended up being a dying Denise.  Once replaced, it was rock solid.

[circlip]

oh, didn't realise I had a reply!

Well, I switched it off between plugging/unplugging, just thought it was a good idea.

There seems to be nothing spilled on the keyboard... I still see no sort of "pattern" to the Caps Lock key led "flashing". It just flashes continuously, that's all.

I edited my last post (on page two) but I'll put it again here.

@meega and all, I found a little yellow sticker that fell off the pcb or somewhere, and it said "A500 P", could this mean an A500+ ? What are the differences between the two?

EDIT: DrDekker... is there a way I can test the Denise chip with a multimeter, and how to do this? I could spring for a Denise next week.

[DrDekker]

As far as I know there isn't any means of testing it, but I found out it was the problem by pressing down on the chip when the A500 was switched on and watched out for the reboots.  Sometimes the Amiga would reboot and other times it would stay on for ages.  I then thought it was just a bad connection, but the problem didn't go away until I replaced the Denise.  The original chip must have had a dodgy leg or something.  It's worth a ago replacing the Denise as she's a pretty inexpensive old girl. :-D

[meega]

circlip wrote:

ED: meega, I found a little yellow sticker that fell out when I opened the A500 up again. it said "A500 P" and then a serial number. What's the difference between an A500 and A500+ ?

The ROMS, the custom chips, and the keyboard itself. That's about it. It allows more chip RAM (1MB standard, and another 1MB can go in the trapdoor), and offers some more video output modes from the Enhanced Chip Set (ECS). Does the A500 have a battery-backed real-time clock as standard? A500+ does. It also uses Kickstart/Workbench 2 (ROM and disks), and is mostly backward compatible for software - especially if the programmers actually followed the rules.