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Mike's Pile of TOS - Atari ST Repair/Refurb

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Great job! This is the thing with retro finds, having to put the effort to get the things to work, keep up the good work and keep us posted! 

 I wish I had the a) time b) space and c) a wife that didn’t think of old computers as shite that should be thrown out.

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A couple of interim tinkerings this evening - the monitor was turning shades of blue/yellow when the RGB connector/cable on the back was not quite straight, even when fully tightened,  so I pushed the cover far back enough to reveal the pins on the underside of the main PCB and reflowed the joints - this is now fixed. I didn't want to take the cover off completely as I am scared of CRTs, so being able to do this was a bonus.


I also ordered a "fully working" NES pad last week in order to solder a standard 9-pin cable to it as per this for use with my Amiga:




It basically takes a NES pad, removes the logic from it and gives a cheap high quality joypad for use on Amiga/ST/etc with the added bonus of rewiring button B to the "up" signal, so up-to-jump games are made much better. My NES pad was yellow, not fully working, and all the rubber bits fell apart on disassembly, so I ordered some new ones and bleached the casing with peroxide cream while I waited for them to arrive.


The bits arrived today so I reassembled it:




I was going to use the cable from a broken Mega Drive pad but the wires were full of some fabric stuff, so I used the one from the broken Cruiser (above) instead. I tested it on the ST with New Zealand Story and it works great apart from questionable diagonal movements on the d-pad, so will do some more tweaking on that. I also couldn't get past level 1-4 but I think that is more to do with my diminishing skills.

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  • 2 weeks later...

Part 4: Floppy Drive Bastard


ST #1 is all done so the only outstanding issue is the floppy drive on ST #2. As mentioned it span up when installed in ST #1 but wouldn't read disks, and both floppy drives were not spinning the motor in ST #2.


I started reading schematics and trawling forums, and set about troubleshooting. The floppy cable on the STFM is soldered to the board rather than socketed, so a quick swap to test it was out of the question - to get around this I popped the cable retainer off so I could get at the pins and test continuity to the plug at the drive end:




All checked out OK so the cable appeared good. I also tested the connection between the solder joints under the board and the pins on the top - again OK but I reflowed the joints anyway. Connected it back up in case this had helped to be met with the same issue.


I then started looking at schematics and started testing continuity between the various ICs in the floppy controller path. I found that the MOTOR ON signal was not reaching the pin on the internal floppy header but was on the external one - these are shared and with the absence of any visibly broken traces I ran a bodge wire from the inductor on this path to the relevant pin on the underside of the board. Hey presto - I now had a spinning drive, but it still wasn't reading any disks - back to how it was on ST #1.


Next step was to replace the electrolytic capacitors on the drive itself as there is definitely a fault on it:




Initial snooping found 4x 10uF and 1x 56uF caps on the two PCBs, a mix of surface mount and through hole. The surface mount ones required stripping a fair bit out of the drive and basically fell off when I prodded them - they were knackered with telltale dried brown gunk and fishy smell when replaced. I replaced them all with through hole ones bent to the side (see pic) and spotted another 10uF cap lurking under a bit of metal so replaced that as well, only to see yet ANOTHER one under a previously unmoved bit of metal. At this point I cursed as I only had 5, so put it back together just in case it would now work - motor now audibly struggling and still no joy.


I am still awaiting new caps so will replace the last one before writing this drive off.


In other news - The CM8833 has entered service in my games room on the Amiga/PS/Saturn/DC and is working well, the broken Sony monitor was collected by someone who is going to try to fix it which was nice.

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  • 2 weeks later...

Can i just say I enjoyed this! It's nice to see old systems get resurrected even if sometimes needs you to have to cannibalise another so that one may live. I'm occasional bodger with a soldering iron so it's good inspiration for a future project to dust off the soldering iron (and soldering skills!).

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If anyone wants to learn basic soldering I would recommend picking up a basic kit with a small (~30W) iron, a 2.5mm chisel tip for the iron, an iron stand, some leaded solder, a set of helping hands and a solder sucker. Wire snips are also useful. You can then get hold of any old broken electronics up to around the early 2000s and have a go at following some Youtube videos (watching out of course for high voltage parts around power supplies).


A basic multimeter with audio continuity checker is also very useful and pretty cheap, and a big bottle of IPA with some cotton buds for the inevitable cleaning is essential.



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3 minutes ago, Fireproofradiator said:

@mikejenkins - I think I'm more or less there with that kit list. All ready to really ruin the kitchen table! Do you have any recommended Youtube channels?

I like Jan Beta from the more hobbyist end of things, and Adrian’s Digital Basement at the higher end. Key point to remember is to heat the things you want to join and feed solder in rather than putting blobs of solder on the iron!

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21 hours ago, gizmo1990 said:

That’s a bit of a dis on poor ol Jan! :( I rate them equally tech wise tbh. They’re both cracking channels with masses of info. 

I can certainly relate more closely to Jan Beta (washing stuff in the shower, less than beautiful soldering, etc.). 

Hey Birt is pretty good too. 

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  • 2 weeks later...

A small postscript - It was extremely sunny and hot today, and I had a day off work, so obviously the sensible thing to do was bleach the battered top case of the keeper ST. I don't have any liquid peroxide (yet) and am a bit hesitant about doing grey plastics with peroxide cream as lots of people have had blooming issues with it, but this case has been sanded to remove graffiti and is generally not in the best shape, so I figured it couldn't get much worse.


After removing the top case and cleaning it with APC, I brushed an even coat of 12% peroxide cream over it, wrapped it in cling film, and left it in the sun for 5 hours. I massaged the cream every hour.






After (apologies for the shadow):




It looks a lot better but is not perfect, and there is still some patchy yellowness on the thin strips around the keyboard as it was difficult to get a layer of cream to stay there. I wouldn't want to try this on anything valuable or otherwise in good condition, and would recommend the immersion method with liquid peroxide instead. It also seems to have attacked what turns out to be the painted blue Atari logo on the badge as a bit of the paint as wrinkled.


We are looking to have another hot and sunny day next week so I will put the keyboard and bottom case out in the sun without any peroxide, as apparently that is what the cool kids are doing nowadays with good results (I will believe it when I see it).


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I couldn't be bothered with seeing if the sun bleaching worked what with the patchy weather, and becoming fed up with disassembled bits of ST lying about the place I did the bottom case with cream and the keys immersed in liquid peroxide. Before:








Considering the state it was in I'm pretty happy with the results, and will look out for a replacement top case at some point. Atari stuff is now DONE, but what's this I picked up this morning?




A new thread is coming up.

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