Amiga 500 intermittently reboots for no reason!

[circlip]

Well,

I ahd another go, and shook the PSU a bit. It sounds like it has something rattling inside, and I can feel something big shifting in there.

Is it safe to open the power supply with it unplugged without electrocuting myself or something?

@ Jope: Sorry about the Keyboard mistake, I just called it a "keyboard unit" maybe I should call it a "main unit" or something, or A500 unit next time?

@weirdami, NZ couldn't be as bad as Papua New Guinea or Indonesia with their power outages, I've lived in both, annoying when chatting or working on an important file!! :crazy:

The rattling in the PSU sounds like a small loose screw or something.

[DrDekker]

Make sure you've got the sound hooked up to your TV or WHY and listen out for 'machine gun' style interference (technical term - ahem).  If you hear such noises - it'll probably caused by a faulty PSU.

[circlip]

I've never received so much help from a forum before guys, so thanks for all your hints and tips! We shall get this thing going somehow!

Hi DrDekker.

I plugged it directly into the Audio/Video ports of the TV, and I didn't get any noises. If you meant for me to use the A520 Modulator, I haven't got the right cable for the RF OUT, I'm only able to use the A/V ports.

I'm still intrigued by the rattling noise though.

[meega]

circlip wrote:
I've never received so much help from a forum before

You've been going to the wrong forums then! :lol:

[DrDekker]

circlip wrote:
 If you meant for me to use the A520 Modulator, I haven't got the right cable for the RF OUT, I'm only able to use the A/V ports.

The audio ports are just fine.  Also check the keyboard connector on the motherboard - a bad connection here can sometimes cause random reboots.

Another cause can be the keyboard controller chip located on the keyboard.  On early models the chip is socketed (red LED for floppy drive?) - on later models (yellow/orange LED - e.g. A500+) the chip is soldered directly.  If it's the former - just lever the chip out a little and press it back home.  Since the fault is random (ish), it could be just a poor connection.  If the capslock light flashes in a particular sequence it usually indicates there's a mainboard fault or the keyboard controller chip has gone west.
 

[circlip]

Hi DrDekker again.

The led colours on the keyboard are: power=orange, floppy=greenish

The Caps Lock light doesn't have any sequence as such, either I switch it on and it's steady, or I switch it on and it just flashes continually. Want me to crack it open again? (this is gettin fun. :-) )

[meega]

The led colours on the keyboard are: power=orange, floppy=greenish

That sounds like an A500+ ... (or I suppose it might be a late A500, I can't recall which way round they are on my 500+, are they the right way round?). What colour is the boot screen when there is no floppy in the drive, what version Kickstart is it?

Ed: ok, you're running it into some green-screen monitor (as you said in another thread), so what does the boot screen tell you...

[circlip]

Yes, meega, it's a green-screen. But I have plugged it into the tv once or twice. Startup screen "white with blue floppy with words "Workbench 1.3"", so I'm assuming it's a kickstart 1.3 if I'm correct.

EDIT: Does anyone think a motherboard replacement will (hopefully) fix my problems? I found a cheap one which I could buy next week. It has no chips.. so if a chip is the problem, I might make no headway.

[meega]

There is a difference between Kickstart and Workbench, an A500Plus will also boot into 1.3 and give the blue Workbench display if you put a 1.3 system disk in the floppy drive. Try removing the floppy, and give it the three-fingered salute (Ctrl+Amiga+Amiga) and tell us what it shows then.

(But you should know if it's an A500Plus, because it says that on the badge on top of the case.)

And further eds: I might just be wasting your time, you might well be entirely correct. The keyboard looks like either an A500 or else a US layout, A500Plus uses the International keyboard with a different Return key.

Also, apologies if I'm getting this wrapped around the wrong way... Rereading your posts makes me think it is indeed an A500.

[circlip]

Hi meega,

Well, I don't have workbench yet...

(that was a floppy I simply tried to boot unsuccesfully with, after reading further into transferring files to an Amiga (I'm getting workbench 1.3 hopefully next week))

But basically it asks for WorkBench 1.3... white screen, blue coloured disk icon. There is no "Plus" badge anywhere.

EDIT: If anyone wants screenshots of anything for further investigating (inside or outside of the A500) I can make them asap.

[Tomas]

Do you have a multimeter handy? then you could check if the psu is giving out the right voltages.

[Tomas]

circlip wrote:
Yes, meega, it's a green-screen. But I have plugged it into the tv once or twice. Startup screen "white with blue floppy with words "Workbench 1.3"", so I'm assuming it's a kickstart 1.3 if I'm correct.

EDIT: Does anyone think a motherboard replacement will (hopefully) fix my problems? I found a cheap one which I could buy next week. It has no chips.. so if a chip is the problem, I might make no headway.

Most likely it is either a chip, bad contact or psu. I would rather invest in a whole machine as a500 goes for very cheap anyways.

[circlip]

I do have a multimeter, I can give it a shot. I saw an Amiga 500 on ebay for about 50 bucks (excluding postage) and I don't want to fork out that much if I can avoid it.

EDIT: Ok, I have the pinout diag, here on the bottom of the PSU.


------\    /------
* +12V \  / * SIGNAL GROUND
        \/       |
         * -12V  |

* SHIELD GROUND *| -5V
------------------

So where should I put each probe? I especially don't know how to test the 5V lines. Forgive me, I've only tested a few "simple" things with a multimeter, never an A500 PSU. :-?

[meega]

circlip wrote:
Hi meega,

Well, I don't have workbench yet...

But basically it asks for WorkBench 1.3... white screen, blue coloured disk icon. There is no "Plus" badge anywhere.

Yep, I believe it's an A500. You were quite correct - but I seem to remember a big red LED, on early ones at least...

When you get the Workbench disk, make sure you get the Extras disk that goes with it as well - and enjoy the font editor  ;-) I think it's just the two disks that you need (but there are one or two others with some versions). Also, you probably won't need them for a lot of games - they often just use the ROM.

When you get your system disks, COPY THEM and use the copies for everything. Never work with the original disks - make them write-protected and leave them that way. The originals are your source disks, make as many copies as you require for your own needs.

[circlip]

Thanks meega, I was thinking of doing that actually. Also if my A500 does its reset thingy, will it ruin the disk?

@Tomas and anyone, check my edited post above with the pins. The diagram really didn't turn out, but you get the idea.

[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. :-)