A500 PSU just popped!

[Powerpie5000]

Ok, I've been out of the loop for a few years now when it comes to the Amiga and therefore decided to buy another A500 to tinker with (not impressed by the prices of Amiga hardware these days!). I just got round to checking out the Amiga tonight and the first job was to give it a quick visual check. It looks good and clean and has never been opened before (seals intact). Checked the trapdoor for any extra RAM and was greeted by the old A501 expansion (gulp!).. Inevitably the RTC battery has puked all over both the expansion and it's metal shielding, but it appears to have been contained to just the expansion board as far as I can tell. Ok, no problem as I'll just get another RAM expansion.

Anyway, I hooked up the RGB cable, PSU, mouse and joystick and was ready to see if it boots. It powered up for about 5 seconds before the PSU gave up with a fairly loud pop followed by a crackling/fizz and dodgy BBQ smell! I didn't even get the chance to switch to the correct input on the TV! The power LED came on and the floppy drive made it's usual click/tick noise and then it died. The power supply is one of the weaker and lighter 2.5A models. I'm now hoping it hasn't taken the A500 with it! I'm also hoping it's just age that made it blow and not something wrong with the A500 itself that caused it to go.... What do you guys think?

Do I buy another old Amiga PSU or try and source a newer third party model from somewhere? I'll open this one up tomorrow and see what has failed inside.

 

[Watson]

I think it would be better to source one of the newer power supplies rather than buying an old one.

 

[Powerpie5000]

I'm just hoping the blown PSU hasn't taken out the Amiga with it! No way of testing though without having to fork out more money for a working PSU.

 

[levo-ace]

It is relatively unlikely to have blown the AMIGA , i have had smoking psu's due to dodgy caps and the AMIGA has always been fine . If you open the psu , the cause is nearly always obvious ( burnt or popped cap , blown apart transistor or diode , etc.. ) .

Fixing is easy , if you can get the part!

post some pics and parts can be sourced , or i could fix it for you? I am also in the UK!

 

[miggymad]

The A500 was probably stored away for a long time before you got it, the battery leakage being a clear indicator there. Your best bet is to source another working PSU locally or thru here to ascertain the A500 is still good to go.

If you need a PSU for testing, send me a PM and we'll work something out

 

[Powerpie5000]

Thanks for the suggestions and offers to help guys, much appreciated ?. I decided to just order another PSU as I'm going to need one anyway. The faulty PSU went out with a bit of drama and something is rattling inside, so I'm expecting a little bit of mess and it's a relatively weak 2.5A unit anyway. The shell and leads are in good shape though with little to no yellowing or any damage etc.... Might be good for a Pico or SFX PSU mod?

The seller said the unit was working before it was sent to me. I suppose even with the A501 battery leak it could have still been working. Maybe it's just bad luck that the PSU blew too. So basically I've ended up with clean looking Amiga (boxed) that may or may not work, a dead PSU and a rotten A501 expansion board. I'm still reluctant to return the Amiga though as it looks in pretty decent condition and has never been opened or tampered with (original seals intact). Even the metal shielding around the ports and through the vents still looks clean and shiny as far as I can see without opening it! It's also an early model with the red power LED made in Germany. Lets hope it still works!

 

[miggymad]

I know you may be reluctant to break the original seal but that battery leakage that has potentially migrated to the shielding needs taking care of ASAP before it has time to move onto more delicate areas of the A500.

 

[Powerpie5000]

It looks like the battery leakage was pretty much contained to the A501 expansion itself thanks to the shielding it uses. I can't see corrosion or any signs of battery leakage to the metal parts or pins in the trapdoor bay itself.

I'll probably open it up any way as I have some little expansions in mind. Just need to see if it works first.

 

[Powerpie5000]

Received my replacement PSU today and will test it out tomorrow. It looks in very good condition and is the heavy 4.3A version. Too tired to try it now though as I'm just about to go to sleep.

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[Timtheloon]

Glad you got a new PSU hope it all works fine

speaking of PSU’s which of the original A500 PSU’s are the best, I always thought the heavy ones were but I’ve seen reports that lighter ones are better, what is the general consensus here?

 

[cugar124]

i have a lightweight one works great with vampire

 

[miggymad]

I have various Amiga power supplies here, ranging from the usual heavyweight A500, lightweight ones for A600/1200, Goiath and the more modern ones.

I tend to tailor the power supply for the machine and what's inside it.

My standard A1200 gets the lightweight whilst my all black A1200 gets the more modern PSU because of the Vampire V2
The rest sit in a box until needed.

 

[Powerpie5000]

I've heard the lighter 4.5A is better as it's more efficient. My A500 came with a light 2.5A PSU and it blew. The replacement PSU I bought is the heavy 4.3A type.

OK, So I finally got round to testing the Amiga again and all I get is a black screen through both RGB scart and RF output. The replacement PSU works fine. The Amiga powers up, and the drive clicks once. Inserting a disc causes it to spin for a second and then it stops. Resetting using the Amiga keys works and the caps key works (led goes on and off).

The drive led will light up after about 30 seconds of leaving the Amiga powered up. Inserting a disk at that point just ends up with it constantly spinning and not reading.

Not sure where to go at this point. Do I just return the whole thing and not bother, or should I open it up and first make sure all the chips are seated properly? ... This probably means I won't be able to return it if it turns out to be a duff board.


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[miggymad]

Here is the defacto fault finding list
​​​​from http://www.amigalove com. It is quite good, especially for those machines that refuse to start and gives possible areas to check first.

https://www.amigalove.com/viewtopic.php?f=6&t=324

 

[Powerpie5000]

Thanks for the link. So it looks like it could possibly be a CIA U7/U300 problem. I'll have to look more in to this.

There's definitely a signal being sent to the TV and the screen goes straight to black when I power up the Amiga instead of showing the usual light grey before the KS screen.

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[miggymad]

Sometimes its as simple as pressing the chips down into the sockets again to fix things. However, I would recommend that you get yourself a diag ROM before doing anything more as it might highlight any other problem areas.