Biting off more than I can chew?

[Simon Carter]

After a little success bringing 8-bits back to life, I took a chance on an eBay bundle of a 2600, a 400, and a 1040ST...

 

The 2600 and 400 were simple enough jobs, however the ST I think is way beyond my abilities to patch up...

 

I was very excited when it arrived as it was a 1040STE, I'd just assumed it was a 1040STFM, thought I'd scored a bit of a bargain (£92 for the 3 computers). Firing it up produced just a white screen, a quick bit of homework led to some solutions, none of which I've tried yet as, upon opening the case, it appears to be a in a very sorry state indeed. From the photos attached, there appears to have been something living under the TOS chips, and also the Yamaha sound chip. It looked like a previous owner had drowned it in coffee, and also sat on the case, judging by the amount of bend in the unit...

 

There's a large amount of crap around the RAM bay (revise that, I've just taken the RAM out and it looks like the remains of an orgy have been dumped in the sockets... ?), and neither the floppy or keyboard appeared to function (no activity from either of the LEDs, and the keyboard appears to have some corrosion on its underside. I do have an STFM I can donate a floppy and keyboard from, but I'd rather not if you guys think it's a waste of time. 

 

There also seems to be a lack of a blitter chip (I thought these were standard in STEs)... just wondered whether a previous owner had removed it

 

Edit: think I found the blitter, I was misdirected by an online motherboard guide...

 

What gives me hope, is that the unit powers up, and I also quite like a challenge! Pics below...

 

Regards

 

Si

 

 

Edited July 22, 2022 by Simon Carter

[TGB1718]

Think of it a a nice long term project

Certainly looks like coffee growth in there.

I wouldn't power it up again until you've managed to clean all that crud off.

Gonna be difficult with the chips that aren't in sockets though.

 

It's not likely the floppy or keyboard will respond to anything until you get the STE to boot

[bfollowell]

I definitely agree with @TGB1718. While most of my repair experience is with 8-bits and I have no direct 16/32-bit repair experience, at the very least, this machine need a thorough cleaning several times over before even thinking about attempting to power it up. Think along the lines of a quart or two of IPA and a couple of good toothbrushes. This one may surprise you after a good and thorough cleanup, but it's going to need that at a very minimum. If there are still issues after that, at least you'll have ruled out all the crud as a direct cause and will be starting with a clean machine.

 

Good luck. I look forward to hearing about your progress.

 

[ParanoidLittleMan]

Considering price it was not bad purchase. At least components are there, nothing relevant is broken.

Fixing is self ? Depends on general knowledge, experience with electronic, computers. Surely need to clean it well, dry . Check contacts, sockets, connectors.

May be some broken components - and that's normal for computer old about 30-32 years.  Ah, and PSU capacitors - if they look old, then they are - best to replace them - electrolyte ones, and they does not cost much.

Just to make it clear - I used 'broken' first time literally. Second time at 'broken components' as case of internal error, not visible from outside.

Edited July 22, 2022 by ParanoidLittleMan
Clarify

[snarkdluG]

I can't really see if it is fungus or just wet dust gather around the legs. Hard to see if any corrosion or rust have accord yet on the board. If it has eaten through the the substrate and gone for the copper traces then there can be some job to do. I think after a good clean it would look a lot better.

[Simon Carter]

I guessed cleaning was going to be the most of it - so a bath of IPA should help deal with most of the rubbish. Off to eBay I go...

 

[Simon Carter]

23 hours ago, TGB1718 said:

Think of it a a nice long term project

Certainly looks like coffee growth in there.

I wouldn't power it up again until you've managed to clean all that crud off.

Gonna be difficult with the chips that aren't in sockets though.

 

It's not likely the floppy or keyboard will respond to anything until you get the STE to boot

The keyboard wont be doing anything, I think - plenty of corrosion on the underside, I'll borrow one from my other ST

[Simon Carter]

23 hours ago, bfollowell said:

I definitely agree with @TGB1718. While most of my repair experience is with 8-bits and I have no direct 16/32-bit repair experience, at the very least, this machine need a thorough cleaning several times over before even thinking about attempting to power it up. Think along the lines of a quart or two of IPA and a couple of good toothbrushes. This one may surprise you after a good and thorough cleanup, but it's going to need that at a very minimum. If there are still issues after that, at least you'll have ruled out all the crud as a direct cause and will be starting with a clean machine.

 

Good luck. I look forward to hearing about your progress.

 

When you say a quart or two (4 pints in the UK ?), are you advocating a full immersion bath? I have 5 litres of IPA ready to go, not sure if completely submerging the mobo is a good idea or not

 

Si 

[351coug]

work your way up to the nuclear option. brush scrub and vacuum and see where you get. 

[bfollowell]

3 hours ago, Simon Carter said:

When you say a quart or two (4 pints in the UK ?), are you advocating a full immersion bath? I have 5 litres of IPA ready to go, not sure if completely submerging the mobo is a good idea or not

 

Si 

No, no, definitely not. At least initially. It just seems filthy enough that it might take that much, when it's all said and done, to get it back into a decent, clean shape.

 

[Simon Carter]

So, gave the STE a scrub down, and I have avenues to investigate, and none of them seem particularly expensive...

 

As expected the TOS Roms are totally shot, removing them cost them some pins, that were sadly left in the socket. New sockets ordered, and TOS roms seem to be available for about a tenner. Not too bad.

 

The Yamaha sound chip I am undecided about - cleaned a lot up, but there appears to be gunk under it, so it could probably do with removing, socketing, cleaning and replacing. My main concern here is the traces leading to and from, don't know if that 'bleeding' would be enough to cause issues. New Yamaha chip, about £6

 

Next issue I found after flipping the board (had a mare removing the rear 'tin foil' surrounding all the I/O sockets). The beige Mitsumi 'thing' appears to have been replaced. By a 4 year old. With no arms. I know my soldering isn't amazing, but come on! That surely cannot be factory work?

 

I've cleaned up the RAM bays as best I can, Ill have more of a go when I have time - any ideas for cleaning up the left hand two bays any better, or will it be a replacement job?

 

As always, TIA

 

Si

 

[Zogging Hell]

You could try some white vinegar in the ram slots if there is corrosion (or other mild acid). Just make sure you neutralise it and clean up after. I've used this on PC motherboards to remove corrosion and gunk from ram slots. You will probably need to do some manual scraping with something small and sharp to clean up all those nicely though.

[Paul Westphal]

I spend much time cleaning and re-capping them before I even fire them up any more. You'll get it running, and it's a good feeling for sure.

 

 

Edited July 29, 2022 by Paul Westphal

[Simon Carter]

So, finally managed to remove the old TOS sockets, horrible job, especially as I don't own a hot air gun. On each of the sockets, a particular pin in a square fitting seemed to be more resistant to flowing to the iron than any others. These were a bloody nightmare to get out. Also think that, either due to my oafishness, or the native 'growth', one of the tracks has come away from the mobo (pictured), am thinking a jumper wire between its origin on the motherboard and the relevant pin on the socket should solve this issue?

 

In addition, the growth under the Yamaha chip is still there are quite hard to remove without taking out the chip, pipe-cleaner and IPA do the job?

 

Lastly, black stuff on the north edge of the Blitter? Tried scrubbing with IPA but it ain't shifting. As @Zogging Hell suggested, some white vinegar to remove.

[TheNameOfTheGame]

Might be time to put it in the dishwasher.

[Zogging Hell]

The difficult pin was probably the ground pin, which when its heating up has a lot more thermal mass capacity (it is almost a heatsink). I would invest in a desoldering gun (the electric kind), they really make a world of difference, and are not to expensive. You literally stick it over the pin to heat the solder, leave it a few seconds and press the suck button while gently 'wiggling' the pin. Really is so much easier and much less risk of damage in my experience. Hot air is really useful for surface mount components but not much cop for thru hole imo.

You could try compressed air to blow that gunk out or a pin with some sort of thin clothe on it. But if that doesn't work the dishwasher may be the way to go as TheNameOfTheGame suggested.

I can't tell from the photo, is that track still attached on one side? Could you resolder it directly to the leg of the chip when you put it back in and then use some solder mask or nail polish to fix the length of wire back where it belongs. Is the via still intact or has that come out?

[Simon Carter]

Managed to get under the Yamaha chip with an interdental brush, wife's idea, bless her. Got the majority of the stuff out, almost like millet.

 

Just need the wife to go without gin for a week or so, so I can get hold of a desoldering gun, would be a decent investment

10 hours ago, Zogging Hell said:

Could you resolder it directly to the leg of the chip when you put it back in and then use some solder mask or nail polish to fix the length of wire back where it belongs. Is the via still intact or has that come out?

This was going to be my solution, likely to be fiddly but who doesn't love a challenge. I normally lose my shit when I have things go wrong, but doing and learning about this sort of stuff keeps me calm...

 

Thanks as always

 

Si

[mickster]

On 8/4/2022 at 7:47 AM, Simon Carter said:

So, finally managed to remove the old TOS sockets, horrible job, especially as I don't own a hot air gun. On each of the sockets, a particular pin in a square fitting seemed to be more resistant to flowing to the iron than any others. These were a bloody nightmare to get out. Also think that, either due to my oafishness, or the native 'growth', one of the tracks has come away from the mobo (pictured), am thinking a jumper wire between its origin on the motherboard and the relevant pin on the socket should solve this issue?

 

In addition, the growth under the Yamaha chip is still there are quite hard to remove without taking out the chip, pipe-cleaner and IPA do the job?

 

Lastly, black stuff on the north edge of the Blitter? Tried scrubbing with IPA but it ain't shifting. As @Zogging Hell suggested, some white vinegar to remove.

A hot air gun can be bought for less than $100 on amazon.  If you want to do work like this even on rare occasion its well worth it to pick one up.

 

 

[mickster]

On 8/6/2022 at 8:33 AM, Zogging Hell said:

The difficult pin was probably the ground pin, which when its heating up has a lot more thermal mass capacity (it is almost a heatsink). I would invest in a desoldering gun (the electric kind), they really make a world of difference, and are not to expensive. You literally stick it over the pin to heat the solder, leave it a few seconds and press the suck button while gently 'wiggling' the pin. Really is so much easier and much less risk of damage in my experience. Hot air is really useful for surface mount components but not much cop for thru hole imo.

You could try compressed air to blow that gunk out or a pin with some sort of thin clothe on it. But if that doesn't work the dishwasher may be the way to go as TheNameOfTheGame suggested.

I can't tell from the photo, is that track still attached on one side? Could you resolder it directly to the leg of the chip when you put it back in and then use some solder mask or nail polish to fix the length of wire back where it belongs. Is the via still intact or has that come out?

I disagree on this a bit.  I have found hot air to be very helpful on removing through hole chips on fragile boards.  The problem with the desolder gun (as compared to air), is that you have to apply the tip to the joint to be sucked out.  Often on fragile boards (for example the xe line of 8 bit computers) this will lift or break the trace.  

 

Both hot air and desolder guns are cheap enough now that they should both be on hand for any type of repair. 

[Zogging Hell]

16 hours ago, mickster said:

I disagree on this a bit.  I have found hot air to be very helpful on removing through hole chips on fragile boards.  The problem with the desolder gun (as compared to air), is that you have to apply the tip to the joint to be sucked out.  Often on fragile boards (for example the xe line of 8 bit computers) this will lift or break the trace.  

 

Both hot air and desolder guns are cheap enough now that they should both be on hand for any type of repair. 

Fair enough (I probably need way more practise with hot air and have never had to work on an XE - thankfully by the sound of it). For a beginner or someone used to a soldering iron/ pump combo though, hot air is a quite a big transition with a larger potential for a disaster if you are not experienced and don't have much to practise on; whereas the solder gun is a lot easier to migrate to imo, and a lot safer/better/quicker than a soldering iron/solder sucker combo. My initial fumblings years ago with hot air were not great on the practise boards I used it on (admittedly I was clueless at the time other than watching some instructional videos on Youtube, which generally make it look a lot easier than it is) and it does tend to spread the heat about a lot, which may or may not be beneficial depending on what you are desoldering and what it is next to. Absolutely agree that both are cheap(ish) now so good to get both, although the OP's missus may miss the gin!

[bfollowell]

I agree with both points. While a hot air rework station is probably better for SMD work, I've had a lot of luck using one with through-hole tech repairing my 8-bits. That being said, now that I have a Hakko desoldering gun, I really can't imagine wanting to use my hot air station nearly as much anymore. In my opinion, it really is the perfect tool for through-hole desoldering work. Your mileage may vary, of course.