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Old 31 October 2015, 00:31   #1
jraclarke
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A500 Floppy Issues

Evening all,

My first post on the board so be gentle....

I've got my original A500 and got it back out about 12 months ago. When I did, I noticed a problem with the disk detection (no clicking). the LEDs were normal and the system checks were as expected (screen colour-flashes etc). An evening of messing around and then unexpectedly it was working again.

I must have had it on a few dozen times since then with no problems - always clicking to detect the disk, each floppy reads with no problem. However, a few nights ago the same problem emerged - no evidence of any disk search at all. I'm no expert, but from what I've read so far I have tried:

- Removing the drive.
- Pressing down each chip (Gary, FAT AGNUS etc.) to ensure they are firmly in place.
- Clean the drive with a cotton bud and alcohol (minus the head - looks clean).
- Gently moving the drive head back and forth a couple of times (moves smoothly).

I don't think it's the head that is the issue, it's actually not that dirty and when the disk is registered, they always load.
The confusing thing is the temporamental nature of it. After the clean, it was working last night, but then a quick test this morning and it was back to normal. Had the same thing the night before, even without a clean.

Could anyone tell me what could be causing this? There are countless problems online to do with the head or dodgy floppy disks, but I can't see many with no "clicking".

It is a Rev 5, 680000 and Epson SMD 400 floppy drive. Give me a shout if there's anything else I can provide!

I would just buy a new floppy drive, but as it's only intermittent I'd like to give fixing it a go.

Cheers,

James
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Old 31 October 2015, 01:24   #2
ReadOnlyCat
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Originally Posted by jraclarke View Post
[...] so far I have tried:
- Removing the drive.
- Pressing down each chip (Gary, FAT AGNUS etc.) to ensure they are firmly in place.
- Clean the drive with a cotton bud and alcohol (minus the head - looks clean).
- Gently moving the drive head back and forth a couple of times (moves smoothly).
[...]
The confusing thing is the temporamental nature of it. After the clean, it was working last night, but then a quick test this morning and it was back to normal. Had the same thing the night before, even without a clean.

Could anyone tell me what could be causing this? There are countless problems online to do with the head or dodgy floppy disks, but I can't see many with no "clicking".
Hello and welcome.

The clicking sound of the drives is created by moving the drive's head one track away from its current position, so if you do not hear that sound when there are no disks in the drive it means that the head cannot move.

This has nothing to do with it being dirty from reading disks and is likely either:
* a mechanical problem which prevents the head from moving
or
* the electronics which control the stepping motor are failing
or
* the stepping motor is failing

Given that giving the head a bit of love seems to help it come back to life this very likely means that the electronics are not responsible for this: these kittens do not come back to life once they fail.

So this is likely either a lack of lubrication in the stepping system which blocks the movement or the motor which is starting to fail and needs a bit of a nudge to get motivated again. The latter being unlikely, motors also tend to fail rather definitely.

As for how to check and fix a possible blocked mechanism I am utterly incompetent so I will leave this to others.
But in the meantime, you can try moving the head very gently along the floppy-in/out axis of the drive to see if that helps at least temporarily (if it resists even just a little bit, do NOT insist).
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Old 31 October 2015, 01:44   #3
jraclarke
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Thanks ROC,

It would be a relief if it wasn't something electronic that was doing this.

I had a go at moving the head earlier and I'm a little worried that I moved it more than I should have (though it did move smoothly). I hope I haven't made things worse.

Should it require a bit of lubrication, what would be best for this?

Thanks for your help so far.

James
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Old 31 October 2015, 03:25   #4
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Originally Posted by jraclarke View Post
Thanks ROC,

It would be a relief if it wasn't something electronic that was doing this.

I had a go at moving the head earlier and I'm a little worried that I moved it more than I should have (though it did move smoothly). I hope I haven't made things worse.

Should it require a bit of lubrication, what would be best for this?

Thanks for your help so far.
You're most welcome as long as you do not mangle my pseudonym into a three letters cold and lonely acronym.

If the head did move smoothly and you did not force it you should be fine.
At least we are now sure it is not mechanically blocked which gives hope that a bit of lubrication will be enough.

Have you tried re-plugging the drive to see if it works again?

Regarding lubrication you should wait for the knowledgeable hardware guys to chime in, anything I could recommend you would probably kill the drive and all pets in your household.
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Old 31 October 2015, 14:20   #5
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Aah, the Epson SMD 400, this is one of my favorite A500 floppy disk drives - it has such a great noisy sound

If it's not a blocked head, then it could be just a loose connection, for example. Check if there is a cold solder joint where the power cable is soldered to the PCB. If it's okay, then my guess is that it's most probably the electrolytic caps that are failing. I have replaced the caps on a couple of Epson SMD 400's and they worked just great after

You can check for bad caps if you open the drive and see whether there is some liquid spilled around the caps.
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Old 31 October 2015, 23:37   #6
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It's a deal ReadOnlyCat! No heartless acronyms. Amigasith, all the caps looked fine fortunately - no evidence of liquid.

Thanks again for the help. I have had it apart again tonight and lubricated the moving parts where I can. I was just about to give up but I plugged her in and she clicked.

It was intermittent at first, but now it seems to search for disks every time it is started (maybe the lubricant working its way in).

However, I think I may have messed things up by removing too many screws to find the problem - is there potential for misaligning the head by doing this (something I only read about after the problem occurred). It is very confused when I insert a floppy and nothing loads. Seems quite a common thing.

So I'll do a little bit of reading in the meantime to see if I can tackle this new problem.....
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Old 31 October 2015, 23:45   #7
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And on top of that. I'm getting an initial red screen error on startup as well - ROM problem, but not sure why this would be playing up now.

(However this does seem to be temporamental itself).

Last edited by jraclarke; 01 November 2015 at 00:29. Reason: Extra details.
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Old 01 November 2015, 21:44   #8
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The other usual suspects you can check: (1) Do you have a 512K RAM expansion with a battery that has leaked? Take it out and try without it. (2) A bad power supply can also cause intermittent issues. PSUs tend to go bad if they haven't been used for a long time. Do you perhaps have another PSU to try?
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Old 02 November 2015, 10:23   #9
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Thanks Amigasith,

Unfortunately no other PSU. I have the 512k expansion, but I can't see a battery on it, am I just being blind? I can pop a pic up when I get home later.

James
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Old 04 November 2015, 00:32   #10
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An update from me, for anyone that's interested.

I realised that the reason that the floppy drive is up the blink is probably the fact that there have been a couple of times that I have plugged in the joystick and mouse while the power was on. I'm guessing this could have screwed the two CIAs, though swapping these over doesn't change anything.

I've definitely managed to misalign the head, but I will take care of this once the drive is fixed (or replaced).

So for the time being I'm keeping an eye out for a decent value spare or repair A500 so that I can try out the chips and a new drive.

I'll keep you posted.
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Old 08 November 2015, 00:16   #11
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Hmm, are you sure the drive is not clicking, or is it just not starting to spin once you insert a disc ?
I am asking because such intermittent disc recognization issues are a very common problem, and have it's cause in some bad contact in the tiny (pin-)switch near the drive's door. To solve this, just put one drop of conatc tspry into the pin and push it down with a screwdriver a couple of times. Afterwards, it will have good contact again for years to come

However, if the drive spins up when you insert a disc, but indeed does not click, then I would have a look at the Agnus 8371 after what I have read in your post. (I would rule out the CIA since you already swapped, them without any change)
You can try to pull the Agus out of it's socket a bit, then push it back in. This normally give it good contact to it's socket again. (be careful not to break the socket! You can also try to push it out from the backside of the mainboard - there is a hole where the Agnis sits)
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Old 13 November 2015, 13:41   #12
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Hi Overdoc,

Definitely the fact that the drive is not clicking (though this is intermittent now). Once it does click, then I insert the disk and it spins up (though I think it's misaligned now).

I've tested the switch (by pressing the pins down with no problems) - on my floppy there is just the one switch which contains two pins - one detects when the write protect is in one position, and the other for when it is in the other position. It doesn't appear that there is a switch just for disk detection alone.

I will try fiddling with the existing Agnus (carefully) tonight, and if no luck then I think I will definitely be looking into replacing it when I can get hold of one.

Is it also possible that both CIAs are faulty anyway?

Thanks,
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Old 14 November 2015, 01:55   #13
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Bit of an update from me. The floppy drive seemed to be ok tonight and was clicking - not sure why, but I nudged the stepper motor along into the correct place and everything worked since. It can tell disks are there. However....

I used the opportunity to try and realign the drive - what an absolute pain! Luckily for me the lower head and stepper motor are attached firmly to the drive so in theory I am only dealing with the upper head (I think). However, three hours of trying tonight and no luck at all, you would have thought I would have stumbled across the perfect position by chance alone. I gave the two heads a clean as well with alcohol.

My alignment technique was that when the disk was (vaguely) recognised and I was given the "disk is unreadable" or "has a read/write error" on what looks like a Workbench backdrop, I would then loosen the two screws on top of the head, adjust the top a little bit at a time, tighten the screws and hit retry.

I will probably work a bit more on the alignment over the weekend and might try to recover the drive at a later date if I'm forced to get a new one. I don't want to lose the loud Epson SMD 400 sound though!
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Old 15 November 2015, 18:52   #14
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I have had the same problem as you with a drive that stopped clicking. I turned out to be one of the CIAs that had failed. I think it was the even CIA, but I'm not 100% sure.
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Old 24 November 2015, 00:30   #15
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Another update from me.

The lack of clicking problem has disappeared completely! However after screwing the alignment, I purchased an external floppy drive and a copy of Xcopy. Luckily, having Action Replay I can boot from df1, even with Kick 1.2, so at least I have a backup option to use my A500 again!

However, I'd really like to get this drive back :-) I've still been trying the manual align, but now using Xcopy's checkdisk to tell me if I'm getting close. A few more hours though and still no luck. Often on the upper head I can get up to the first 8 tracks returning a 0 (ok), but then everything else will return 2 (No sync). The strange thing is even after a partial success, running it again might return a complete failure. The lower head is out of alignment but I have no idea why as it's fixed so cannot move!

Is it still possible that this is just a hardware problem? It just seems so inconsistent. I would have thought I would have stumbled across the right alignment by chance alone by now!

Cheers,

James
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Old 24 November 2015, 12:18   #16
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It could be the track 0 sensor that is off - that way both heads would have trouble hitting a track. This one has to be adjusted first. It is found at the end stop and can be moved around after loosening the screw. It should be fixed with some glue, but I had one drive where it was was loose and thus the drive would only work occasionally as the sensor would move around a little due to vibrations.
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Old 25 November 2015, 00:54   #17
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Thanks demolition.

I took a look tonight. On my drive (Epson SMD 400), the track 0 sensor is mounted to the PCB, which is in turn mounted to the drive casing so it literally cannot be moved. This though has made me realise something. Given the fact that only the top head is movable, yet the lower head and track 0 sensor are fixed, there can only be one thing that I can think of that is causing both the upper and lower reading to fail - the stepping motor.

I ran Xcopy again and watched the positions that it was scanning, it does seem to have a hard time getting from track 0 to 1 and it doesn't feel smooth at the extreme end of the rail, I'm wondering if a failing stepping motor could be putting it consistently between tracks (ReadOnlyCat suggested a failing motor could be the cause though they tend to fail more spectacularly than this).

Anyway, to narrow down whether it's the stepper motor failing mechanically, or one of the chips, I'm going to hook up my external floppy internally. I'm just waiting for the floppy power cable from ebay as my existing internal has the power cables soldered in by the looks of it.

James
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Old 25 November 2015, 11:01   #18
hooverphonique
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Originally Posted by jraclarke View Post
I ran Xcopy again and watched the positions that it was scanning, it does seem to have a hard time getting from track 0 to 1 and it doesn't feel smooth at the extreme end of the rail, I'm wondering if a failing stepping motor could be putting it consistently between tracks (ReadOnlyCat suggested a failing motor could be the cause though they tend to fail more spectacularly than this).
If it moves fine elsewhere, the motor (electrics) and chips will be fine.. have you checked that there's no old hard grease or something in the way?
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Old 25 November 2015, 14:56   #19
jraclarke
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Hi hooverphonique,

Had a look and there is no old hard grease there, in fact I added some new stuff recently. Do you think it could be internally in the stepping motor?

Thanks
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Old 25 November 2015, 16:22   #20
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Hi hooverphonique,

Had a look and there is no old hard grease there, in fact I added some new stuff recently. Do you think it could be internally in the stepping motor?

Thanks
I'd say no, because it needs to turn several revolutions to move the heads end to end anyway, and that seems to work..
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