Acorn Archimedes A3000 Repair

[Roxbury]

Well inspired by your success AK I thought I would have a go at my A3000 with battery corrosion as well. Looks like I'll be needing to get hold of similar components!

[Arcade King]

Well inspired by your success AK I thought I would have a go at my A3000 with battery corrosion as well. Looks like I'll be needing to get hold of similar components!

[ATTACH=JSON]{"alt":"Click image for larger version Name:\tIMG_1537.jpg Views:\t7 Size:\t356.1 KB ID:\t2114864","data-align":"none","data-attachmentid":"2114864","data-size":"medium"}[/ATTACH]

 

repair log coming? :D

I have a couple of those 9 pin mini dins left if you want to replace yours.

[Roxbury]

 

repair log coming? :D

I have a couple of those 9 pin mini dins left if you want to replace yours.

 

Cool thanks for that, will definitely use 9 pin mini din. Don't suppose you have any keyboard connectors spare :P

 

[Roxbury]

Have removed all the components in affected area now. Will need to clean up the board further now that everything exposed.

 

[Arcade King]

Have removed all the components in affected area now. Will need to clean up the board further now that everything exposed.

 

[ATTACH=JSON]{"data-align":"none","data-size":"thumb","data-attachmentid":2116332}[/ATTACH]

 

PM me your addy if you want those bits

[Roxbury]

Have now finished checking all traces in affected area. Thankfully good schematics available. Only 30 odd traces to fix..............

[Roxbury]

 

Have made some progress. I pulled just about everything with corrosion out. I used the schematics from here to go over everything in the affected area to find all the broken traces. I then put some laquer on the board to preserve tracks that were still working.

 

 

Some patches put on the top, and replaced all the components/sockets. Thanks to @Arcade King for sending the 9 pin mini din mouse connector!

 

Most traces fixed underneath board. Tried to be neat, but so many traces needed that is hard to do.

 

Placed chips back into sockets, and a new battery. Tested the power supply, still working ok.

 

 

Time to try it out - plugged the keyboard in as well so I could clear the CMOS by holding DEL while booting. If you don't do that after battery change you can't boot up. And success! Just tried the easy way with the mono composite connection.

 

 

Things to do next:

Clean case & keyboard thoroughly

Build RGB cable

Bypass the audio filter

Building Amiga Mouse adapter

Test keyboard & mouse

Get some games running!

 

Edited March 28, 2020 by Arcade King

[Arcade King]

Awesome work mate, It's like new.

I fixed up your doubled up attachments also.

[Roxbury]

Built a Scart RGB video cable. Pin out for the A3000 connector below:

 

 

The A3000 also has a 3.5mm stereo plug for sound out so you are not reliant on the internal speakers.

 

 

 

I did my usual trick of buying a decent old scart cable from a tip shop then modifying. I am showing the 9 pin connector prior to adding backshell.

 

[Roxbury]

When trying out the scart cable, the colours were a bit off. After checking all the connections, it was time to look at the video circuit. Underneath diodes just before the RGB socket, I noticed some more corrosion.

 

 

I removed all the diodes, and found a couple more broken traces.

 

Added a couple more trace connections, soldered in some new diodes and RGB output now working fine.

 

 

While I am at it, the A3000 has a low pass audio filter that is recommended to be removed. This will improve the audio output. This is a simple mod, with more details here https://stardot.org.uk/forums/viewtopic.php?t=13630

 

For this model the steps are:

 

- Disconnect the +ve leg of electrolytic capacitors C65 and C70

- Solder a wire from Pin1 of LM324 IC39, to +ve leg of C65

- Solder a wire from Pin8 of LM324 IC39, to +ve leg of C70

 

See pic below after mod completed.

 

[Roxbury]

Some of the keys on the keyboard don't work. After confirming all the traces from the keyboard ribbon connector, it's time to look at the keyboard membrane ribbon connector itself.

 

There is some corrosion you can see inside the ribbon connector under the plastic. First thing I tried though was adding some conductive paint to the exposed "pins". This helped with one of the failing connections.

 

 

I identified the pin connected to the keys that weren't working by looking at the membrane and tracing the connections from the key pads. I carefully peeled the plastic on the membrane ribbon back to expose the underlying tracks.

 

 

I began carefully scraping away the existing conductive material. As this was very poor due to the corrosion damage, I scraped it all away.

 

 

I used some painters tape to make a guide for applying the paint with a small brush. I really recommend doing this, makes it much easier and neater.

 

 

After leaving to dry overnight, all keys working now.

 

[Roxbury]

I don't have an Acorn 3 button mouse, but the good news is that an Amiga mouse can be used with an adapter, the only disadvantage is there is no third button.

 

 

I found an old 9 pin cable with the right plug for the Acorn socket. Simply solder a 9 pin male socket on the other side and connect the matching connections together. One thing to note the mouse socket on the A3000 is in a bad spot underneath, and there is not much room to plug the cable end into the socket. I had to remove the casing from the socket connector on the end of the cable I used, otherwise it wouldn't fit through the case hole.

 

After carefully removing the case and resoldering the 9 pin connector pins, placed some heat shrink around the end to help keep together.

 

​

 

Edited April 10, 2020 by Roxbury

[Arcade King]

Thanks for putting the info up for the audio mod, I haven't done it yet.

[Roxbury]

The floppy drive that came withe this Archimedes doesn't work properly. When inserting disks, they don't really click into place. It feels like something in the mechanism isn't working fully. Rather than trying to fix this, I have gone for a Gotek USB floppy emulator solution. I have opted to use the HXC firmware which costs 12 euro to purchase. However I understand that the FlashFloppy firware will also work on the A3000 if you want a free option.

 

To use a Gotek you will need a longer floppy drive ribbon cable, and to extend the floppy drive power cable to reach.

 

As far as I know there isn't a floppy image manager program available for the A3000.

 

The HXC firmware has an OSD option where it will overlay the screen using one of the RGB outputs to display the selected file name and list of files on the USB stick. This requires a couple of wires to be soldered to the goteck for sync and video signal, recommend using the green signal. it is best to use probe hooks to clip onto a leg or IC to pick up the signal rather than soldering directly to the computer motherboard.

 

 

I chose to pull the green signal from D14, just behind the RGB connector. I pulled the C sync from L24 pin 1 or 2. There is a jumper over pin 1 & 2 of LK 24. I removed the jumper, hooked onto the base of one of the pins then placed the jumper back on.

 

 

When pressing one of the Gotek buttons the screen overlay comes on, allowing you to see what files you are cycling through. When you stop pressing the buttons, the image goes away after a few seconds.

 

 

Good thing about the Gotek and the A3000 is that it fits in perfectly, and even the screw holes line up.

 

[Roxbury]

Well have now finished most things I want to do with this Archimedes project. Only other thing I want to do is make a joystick adapter, although this will require a bit more research and planning. It's not so simple!

 

I have to say, as a long term Amiga lover the Acorn 3000 is a very nice computer, with some really good capabilities. I was really shocked to find the soundtrack in Lemmings (one of my favourite Amiga games ever) is noticeably better on the A3000. There are some great games out there for it, so I am really happy to have this up and running nicely now. Last pic is of Pacmania running - a very nice arcade conversion. If the A3000 had become more mainstream for games, there could be some real quality conversions on it.