exxos's Atari, Amiga & retro forum

I'd have thought a gentle sand perpendicular to the rotation would give a higher degree of grip rather than scratches parallel to the direction of travel.

stephen_usher wrote: 18 Sep 2021 21:58 I'd have thought a gentle sand perpendicular to the rotation would give a higher degree of grip rather than scratches parallel to the direction of travel.

It would but if the pulley is small as the case usually is with drive motors and has flanges to keep the belt in place, this might be the only option to rough it up enough. The large pulley as you rightly say could be roughed up transversely.

PhilC wrote: 18 Sep 2021 22:09

stephen_usher wrote: 18 Sep 2021 21:58 I'd have thought a gentle sand perpendicular to the rotation would give a higher degree of grip rather than scratches parallel to the direction of travel.

It would but if the pulley is small as the case usually is with drive motors and has flanges to keep the belt in place, this might be the only option to rough it up enough. The large pulley as you rightly say could be roughed up transversely.

Yeah, the drive motor is flanged and quite narrow, not figured it out yet.

Sorted out a few things today with the Seltron FDD.

Number 1 was that the drive motor pulley was either not as clean as I originally thought it was, or it's picked up a load of junk as a result of me playing around with the replacement belts.

As I was planning to lightly sand it anyway, I took the motor out for better access and got it cleaned and sanded.

I also disassembled the whole top hub that grips the disk and cleaned it with IPA, re-lubed the bearings, and reassembled, and at the same time removed the main drive-wheel off the bottom of the drive hub and cleaned, re-lubed all the bearings for that and re-assembled with the now lightly sanded drive wheel which is more grippy now.

So, drive wheel and hub assy all spin nice and freely now, though I am still getting drive belt slippage. More on that later.

Next, I did a random capacitor removal from the motor control board, and the cap was reading half it's stated value, so now I don't trust any of the caps on there and have ordered replacements. Annoyingly I can't find my big box o' caps, as it's in another box somewhere meaning ordering more!!! One looks quite nasty, and the heat shrink has split so it needs to go.

Now, slippage. The new belts I got are not fabric reinforced, so have a bit of stretch in them, and don't work very well, so my hunt goes on. I do have some more coming, but they may suffer the same fate. The original belt does drive the disk, but is still slipping on the motor pulley. It isn't slipping on the disk drive pulley, probably because a) I sanded it and it's quite grippy b) there is a much larger surface area to grip.

Whilst running a Locksmith speed test, I used a smooth bar to tension the belt and seemed to have some luck in increasing the overall speed, but I think until I know the caps for the motor control board are good, then I won't necessarily be getting a useful result.

Of note, the motor does have additional mounting holes to adjust the tension, and whilst it is now at maximum, I may just be able to tweak it to add a little more.

One other thing that did spring to mind is that I'm wondering if the motor drive pulley originally had a rubber coating, now long gone, to help avoid slippage? I haven't seen it before, but I suppose it is possible, as the spindle is not much wider than the motor spindle itself.

On another positive note, I have at least worked out how I can trim the 4mm belts down so they fit ok!

So, mixed progress. Isn't that always the same with old micros?

stephen_usher wrote: 19 Sep 2021 18:49 So, mixed progress. Isn't that always the same with old micros?

Yep, about normal 😁

Feels like progress though and I have a path forwards.

Ok, capacitors have arrived, so that's a start. At least I can swap them out and see if there is any improvement.

I'll measure all the old ones once removed, see what they look like compared to the one I previously removed that was 'particularly unwell'.

@PhilC Looks like today is the day for Apple ][e soundcards as my Mockingboard arrived just now with some software too :)





Will hook it up and give it a try later.

@rubber_jonnie looks cool. I've got to download some software to test it with once I've built it.

@PhilC Got it plugged in just now and tested, with the included software and it works just fine, so need to try some of the supported games now. Starting to look like a proper Apple ] [e now with the addition of a few cards 😁

My only minor gripe is that the onboard speaker plays through the Mockingboard, so speakers are a necessity. I'll have a dig through my cables to see what I can use as an extension. Need to copy the disks I was sent to images too, so I can drop them onto my FloppyEMU.