kixs wrote:

Well done 😀

Hvala

386_junkie wrote:

Come to think of it... this was the same thing that was happening to the FDD I repaired. It (the LED) lit up but there was no noise coming from the drive, no spinning motor, head reading the disk... nothing.

Changing the capacitors bridged a couple that had blown open circuit and put back into tolerance a couple more... it did the job, from seemingly a dead FDD to a functional one. The capacitors charge up and store current before bursting it back out once a threshold is reached... it is likely that the motor which spins the disk is driven by one of these electrolytics.

Before going and butchering the functional drive... it may be worth your while (and a euro or 2 to buy new capacitors) just to replace them, it sounds most likely to be the fault.

Thanks for this info, this would make repairing the FDD a lot easier! I'd need to check if this particular floppy drive actually has caps and which ones it has and how many...now I hope that I actually marked the drive so I won't have to go test all of them again 🤣!

Cheers! 😁

Tetrium wrote:

Thanks for this info, this would make repairing the FDD a lot easier! I'd need to check if this particular floppy drive actually has caps and which ones it has and how many
Cheers! 😁

No probs.

If it does have caps... they'll be around 5 of them. When you open it up you might as well just pull all of them off and replace them all. You might find 1 or 2 might still be ok... but it is better to replace all of them as if there are any still in spec... they won't continue to be.

Once you get the caps off, check under a magnifying glass their values. For me it was; -

22uF - 25v ... x 2
1uF - 50v
0.22uF - 50v ... x 2

Replacing like for like.

All the best.

386_junkie wrote:

kixs wrote:

Well done 😀

Hvala

I didn't expect that one for sure 😁

I had this issue with my PS/2 Model 40SX for the last couple of years, however it was only very recently that I got access to it again (was in storage in another state for over a year... 😢 ).

The floppy drive refused to read any disk, always got a "General Failure reading drive A" error. Reading around I found some people re-aligning heads, some people replacing caps... and so on.

Anyway, I fixed the DALLAS IC on it since the built in battery was totally dead, and then when trying to get it to boot from a bootable disk, it just randomly started working. Got the reference disks off the internets and configured the machine and now it's working perfectly 😀

I probably will replace the caps on the drive anyway since they are so... tempremental after all these years. It deserves a bit of TLC 😀

orinoko wrote:

I had this issue with my PS/2 Model 40SX for the last couple of years, however it was only very recently that I got access to it […]
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I had this issue with my PS/2 Model 40SX for the last couple of years, however it was only very recently that I got access to it again (was in storage in another state for over a year... 😢 ).

The floppy drive refused to read any disk, always got a "General Failure reading drive A" error. Reading around I found some people re-aligning heads, some people replacing caps... and so on.

Anyway, I fixed the DALLAS IC on it since the built in battery was totally dead, and then when trying to get it to boot from a bootable disk, it just randomly started working. Got the reference disks off the internets and configured the machine and now it's working perfectly 😀

I probably will replace the caps on the drive anyway since they are so... tempremental after all these years. It deserves a bit of TLC 😀

Thanks for sharing and shedding more light n these temperamental with age drives.

I'm curious if the "General Failure reading drive A" error is due to one of the other 5 caps on their way out or if this is more to do with head re-alignment. As they're are 5 caps (generally) across the range of 1.44M and 720k drives it would be interesting to figure which cap assists with which function and depending on which cap is on their way out limits the drive to certain functions. How I mean is.. with the drive I was working on, I couldn't even hear the motor spin the disk never-mind accessing the A:\ in command. Whereas the caps on your drive, possibly the one that drives the motor let you go as far as A:\... ( ? )... but the cap that drives the reading and writing of disks was drying out, giving you the "General Failure reading drive A" error, possibly? If this is the case and it is relative to a cap whose dielectric was drying out and becoming increasingly resistive, it may come around again in future.

Regards to the DALLAS IC, this is in the 40SX? Did you replace the IC to get it working again or have you been able to use the system without replacing it? I've had to replace a couple of those chips recently, it's not so bad... just so long as they are socketed. I've a couple of motherboards in the queue for a work over which have these DALLAS IC's but without a socket, so it's a job when I've a little more time to de-solder the IC's first and install a socket in place.

The things we do to preserve our parts! 🤣

386_junkie wrote:

Thanks for sharing and shedding more light n these temperamental with age drives. […]
Show full quote

Thanks for sharing and shedding more light n these temperamental with age drives.

I'm curious if the "General Failure reading drive A" error is due to one of the other 5 caps on their way out or if this is more to do with head re-alignment. As they're are 5 caps (generally) across the range of 1.44M and 720k drives it would be interesting to figure which cap assists with which function and depending on which cap is on their way out limits the drive to certain functions. How I mean is.. with the drive I was working on, I couldn't even hear the motor spin the disk never-mind accessing the A:\ in command. Whereas the caps on your drive, possibly the one that drives the motor let you go as far as A:\... ( ? )... but the cap that drives the reading and writing of disks was drying out, giving you the "General Failure reading drive A" error, possibly? If this is the case and it is relative to a cap whose dielectric was drying out and becoming increasingly resistive, it may come around again in future.

Regards to the DALLAS IC, this is in the 40SX? Did you replace the IC to get it working again or have you been able to use the system without replacing it? I've had to replace a couple of those chips recently, it's not so bad... just so long as they are socketed. I've a couple of motherboards in the queue for a work over which have these DALLAS IC's but without a socket, so it's a job when I've a little more time to de-solder the IC's first and install a socket in place.

The things we do to preserve our parts! 🤣

On my system (actually, both my IBM PS/1 Model 2121 (if I remember correctly), and my PS/2 Model 40SX had this General Failure reading drive A error show up when accessing the drive with known good disks. The spindle would spin for a few seconds and the drive access LED would light up and then after like 3 seconds it would give up and show the error.

To be perfectly honest with you, growing up with an electronics repairman for a dad, he taught me one particularily good piece of advice when working on equipment. If you suspect one or more caps are dead, 'replace them all'. It's as simple as that. I really would not recommend just replacing the one or two caps that may have gone open circuit or become highly resistive. Heck, the caps on these drives are so cheap, you might as well replace them while you have the drive out and showing its guts.

I will admit, I drove my Model 40SX from Adelaide to Melbourne just after Christmas last year, and *maybe* the constant 9 hours long vibrations and bumps while on the road did something to the alignment of the heads? It could just be I had a slightly misaligned head and now it's ok. Either way, I will be replacing the caps on the drive ASAP (I am moving in a couple of days to a larger place so I can have room for the rest of my machines (which are mostly all in Adelaide still)).

Ok this is getting quite long now.

Oooo, the DALLAS chip. Ok so on my Model 40SX, it is thankfully socketed, so I just popped it out, got a hobby hacksaw (they are tiny hacksaws), and cut into and carefully chiseled away part of the top capping, exposing the internal battery wires. I carefully cut one of the wires to the battery so it was disconnected, and then I got myself a CR-2032 battery holder, and matching battery, and soldered it in place.

Anyway, here's a couple of photos 😀

And yeah, I agree - we really do go through a lot for these old machines 😀 I thoroughly enjoy every moment of it 🤣

386_junkie wrote:

No probs. […]
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Tetrium wrote:

Thanks for this info, this would make repairing the FDD a lot easier! I'd need to check if this particular floppy drive actually has caps and which ones it has and how many
Cheers! 😁

No probs.

If it does have caps... they'll be around 5 of them. When you open it up you might as well just pull all of them off and replace them all. You might find 1 or 2 might still be ok... but it is better to replace all of them as if there are any still in spec... they won't continue to be.

Once you get the caps off, check under a magnifying glass their values. For me it was; -

22uF - 25v ... x 2
1uF - 50v
0.22uF - 50v ... x 2

Replacing like for like.

All the best.

I checked, but neither the "bad" drive nor it's potential donor seemed to have capacitors at first glance, though if they do, they are probably hiding under some shielding plate (the plate that some floppy drives had to protect their underside, so to say).

Will check again later though, but I will be remembering this. Thanks again 😀

It's also worth noting that not all PS/1 and PS/2 drives used the same value capacitors. Mine use totally different values to what is listed above. It would be worth checking your drive before going out and buying replacements.

I have a list of the values on my machine at home, I'll grab them and upload them later just for curiosities sake.

Tetrium wrote:

though if they do, they are probably hiding under some shielding plate (the plate that some floppy drives had to protect their underside, so to say).

Will check again later though, but I will be remembering this. Thanks again 😀

Yea, I had to take a plate off the top; -

... was pain in the caps to get it back on too. Physically, the electrolytics you can see on the PCB are tiny, and as Orinoko suggests... if you have them, they may be different values from what I listed.

Your welcome.

orinoko wrote:

I will admit, I drove my Model 40SX from Adelaide to Melbourne just after Christmas last year, and *maybe* the constant 9 hours long vibrations and bumps while on the road did something to the alignment of the heads? It could just be I had a slightly misaligned head and now it's ok. Either way, I will be replacing the caps on the drive ASAP (I am moving in a couple of days to a larger place so I can have room for the rest of my machines (which are mostly all in Adelaide still)).

Oooo, the DALLAS chip. Ok so on my Model 40SX, it is thankfully socketed, so I just popped it out, got a hobby hacksaw (they are tiny hacksaws), and cut into and carefully chiseled away part of the top capping, exposing the internal battery wires. I carefully cut one of the wires to the battery so it was disconnected, and then I got myself a CR-2032 battery holder, and matching battery, and soldered it in place.

And yeah, I agree - we really do go through a lot for these old machines 😀 I thoroughly enjoy every moment of it 🤣

That right there is a proper PS/1... you are not messing around with that thing, it's a beast! I managed to find a PS/1 last year but have not found much time yet to play with it... I will soon though. For now here's a wee snap: -

Learning about your drive to Melbourne it does sound more likely to be the culprit... if in doubt, bump it about! 🤣 Though It's good to hear it's now still working, I've never seen a drive perform that requires its heads re-aligned so I'll keep your experience in mind. Replacing the caps will be good practice, but as the drives are still working for now, you are in no hurry as yet.

I'll need to put some time aside and modify some more of the RTC's, they are quite invaluable and alongside silica packs and heatsinks for chipsets... will help preserve our motherboards for a ridiculous amount of time, hopefully for when I retire...

The force is strong! 😁

386_junkie wrote:

That right there is a proper PS/1... you are not messing around with that thing, it's a beast! I managed to find a PS/1 last yea […]
Show full quote

That right there is a proper PS/1... you are not messing around with that thing, it's a beast! I managed to find a PS/1 last year but have not found much time yet to play with it... I will soon though. For now here's a wee snap: -

Learning about your drive to Melbourne it does sound more likely to be the culprit... if in doubt, bump it about! 🤣 Though It's good to hear it's now still working, I've never seen a drive perform that requires its heads re-aligned so I'll keep your experience in mind. Replacing the caps will be good practice, but as the drives are still working for now, you are in no hurry as yet.

I'll need to put some time aside and modify some more of the RTC's, they are quite invaluable and alongside silica packs and heatsinks for chipsets... will help preserve our motherboards for a ridiculous amount of time, hopefully for when I retire...

The force is strong! 😁

The machine under the thinkpad in that picture is my PS/2, my PS/1 is still in Adelaide unfortunately... But yeah it's a bit of a beast. Or a boat anchor as some would say. At least it has ISA slots in it! Can't stand MCA cos of reasons I wont get into here.

Your PS/1 looks excellent 🤣 Nice tower design too. These things were built with character. 😀

Yeah I honestly don't know if the drive over to Melbourne really did anything. All I know is that last time I used it (in Adelaide), the drive refused to read any disk, and then after I drove it to Melbourne, it read disks. Which is good, cos I really didn't want to have to pull the hard drive and install stuff onto it using another machine etc. I'll definitely be replacing the caps asap anyway, long before it fails again. Electrolytics have a limited life regardless so this is something that will happen again in the future anyway.

If you're in or near Melbourne, I'd be happy to modify the DALLAS IC's for you. I quite enjoy putting on a movie or whatever and working on these things 🤣

And yeah, little R2 watches everything I do. hahaha

My mistake, a beast of a PS/2 😁 Yea MCA is a funny bus... still tryin to get my head round the various types and length (16 & 32 bit bus's). The PS/1 tower is luckily both ISA & VLB... got quite a surprise when I opened her up for the first time. The only MCA system I have is the Model 80, don't intend to get any more.

I'm flying the retro computing flag for Scotland... though let me know how you get on with your drives when you get round to it.

Cheers

386_junkie wrote:

My mistake, a beast of a PS/2 😁 Yea MCA is a funny bus... still tryin to get my head round the various types and length (16 & 32 bit bus's). The PS/1 tower is luckily both ISA & VLB... got quite a surprise when I opened her up for the first time. The only MCA system I have is the Model 80, don't intend to get any more.

I'm flying the retro computing flag for Scotland... though let me know how you get on with your drives when you get round to it.

Cheers

I did find MCA interesting (kinda like I find VLB interesting) but it's mainly the proprietary stuff that has always pushed me away from liking it.

Tetrium wrote:

386_junkie wrote:

My mistake, a beast of a PS/2 😁 Yea MCA is a funny bus... still tryin to get my head round the various types and length (16 & 32 bit bus's). The PS/1 tower is luckily both ISA & VLB... got quite a surprise when I opened her up for the first time. The only MCA system I have is the Model 80, don't intend to get any more.

I'm flying the retro computing flag for Scotland... though let me know how you get on with your drives when you get round to it.

Cheers

I did find MCA interesting (kinda like I find VLB interesting) but it's mainly the proprietary stuff that has always pushed me away from liking it.

Oh i find MCA very interesting too, but trying to find MCA based cards where I am is next to impossible. Actually, I've never ever seen one with my own eyes, always online only. Was very strange when I was a kid opening up an old PS/2 for the first time and seeing these things that looked like brown back to front PCI slots.

ISA, VLB and PCI is way more fun anyway - so much more to choose from and you know you're gonna get *something* when scrapping an old machine.

386_junkie, still in the middle of moving - I'll have my machine area set up hopefully soon. Gonna address that drive once I do!

orinoko wrote:

Oh i find MCA very interesting too, but trying to find MCA based cards where I am is next to impossible. Actually, I've never ever seen one with my own eyes, always online only. Was very strange when I was a kid opening up an old PS/2 for the first time and seeing these things that looked like brown back to front PCI slots.

ISA, VLB and PCI is way more fun anyway - so much more to choose from and you know you're gonna get *something* when scrapping an old machine.

386_junkie, still in the middle of moving - I'll have my machine area set up hopefully soon. Gonna address that drive once I do!

Where do you live?

I live in the eastern suburbs of Melbourne... Why's that?

orinoko wrote:

I live in the eastern suburbs of Melbourne... Why's that?

Ow..nvm, that's one heck of a swim 😁

The PS/2 40 is an ISA machine.

PeterLI wrote:

The PS/2 40 is an ISA machine.

It is... I wonder what they were thinking in the manufacture for this one, possibly an experiment to see how it is taken by the market of the time? Though dropping their own prop bus for the widely used ISA... is not very IBM is it?