Amiga 5(00) alive

The Nicotine Amiga

Following the A1200 upgrades and recapping I've turned my attention to the old A500.

Digging this old beast out as old games don't really play too well, or at all, on the A1200. Hunter is one example, which is still one of my original boxed games that I'd like to play and doesn't work on Whdload. 

This was my first Amiga although I didn't get this new. Instead it was from someone who had already modified this computer with additional Zorro cards in a custom baseboard. The external floppy drive still exists, but I got rid of the base board years ago (somewhat regretting that now). 

Once I had my A1200 there was little to bring me back to the A500 back in the 90's as all I really wanted to do was play the new AGA games. This meant the A500 becoming boxed up and rarely taken out again. Something did stop me selling this on, which could have been the memories of upgrading from my old Speccy and seeing what I'd been missing all along. 

Firing up the old hardware

A quick test of this computer looked promising. Old floppies are still working, which is a surprise with the age of the floppies and hardware. 

I sat down for a long session of First Samurai and Simulcra and then I started experiencing random glitches and system crashes. Not being sure of the cause I attached an external GoTek and tried more games. Some worked well, but other crashed. Something subtle is failing. 

Cracking open the case

Although I've had a childhood history of opening nearly every object with screws, I didn't ever open up my A500. It's been opened up prior to me owning this as the hardware was upgraded to 1MB chip ram. There's also a mystery hole in the case, next to the floppy, which could have been for a switch.

Dusty, but not too bad

First impressions were not as bad and I expected. It was a bit dusty inside, but no leaky caps or modification surprises. I wondered if this was a very early 500 model but this is a later Rev 6A. 

The upgraded chip ram appears as socketed chips along the bottom of the board. Whoever soldered these managed to flick solder around the board. I was able to remove this solder with a brush and ensure that no future solder would short something on the board.

Closer inspection shows something has happened to the jumper pads next to the ROM chip. The pads have been destroyed when the additional memory was added.

A quick clean with Isopropanol helped remove some old flux off the underside of the board and mopped up the old grime from the top side.

Repairs and future proofing

Reflowing some of the old solder around the jumper pads and memory modules was done to ensure the connections are as good as possible. Glitches could be down to poor memory solder connection. Some pins didn't seem to have much solder at all, others didn't appear to flow onto the motherboard pads properly. 

Running the A500 again with games still seemed to have graphics glitching, although I've not had a crash which stopped the system running. 

Moving on next to capacitors. 

Retro Bench Capacitor Kit

Retro Bench sell a capacitor kit for all revisions of the A500. There are more capacitors here than my Rev 6A needed as some revisions came with different values. The guide was excellent with colour coding used to identify caps and clear specification of polarity.

The only real issue with the replacement kit was the size of the 3300uF capacitors. They were much taller and wider than the originals. This means the shielding doesn't fit back level and soldering the capacitors close to the board is also difficult due to the wider spacing of the legs. 

This job didn't appear to be required as all removed caps looked in good condition and leak free, but doing this now is a good idea for future proofing. 

Firing up the A500 again and there's still some glitching going on. One game caused a reboot without Guru Meditation and subsequently rebooted 3 times. All caps were reinspected and look fine, next suspect is the power. 

Crashes were happening with the A1200 PSU and I didn't even bother trying the original A500 supply as it is probably in much worse shape. Instead the new Mean Well PSU was put into action.

New Mean Well PSU

This power supply worked perfectly and from what I could tell all games ran without a problem.

Finally

The good news is that no more crashes or odd graphic corruption (so far). PSUs are getting old and problems can be subtle. 

Great fun and some frustration getting this old computer up and running. I'm hoping it says this way for years to come.