Deunan wrote on 2023-03-08, 14:50:Could be a problem with the signals that tell the drive to step the heads, and direction. Possibly some traces got eaten away by the corrosion you mentioned. Did you try running IMD and testing the head movement in alignment test?
The IMD alignment test does nothing - all question marks and don’t hear the heads moving at all
CharlieFoxtrot wrote on 2023-03-08, 15:54:I just recently repaired an ALPS drive (DFP723D33A, 34 pin, media-sense) on my recently acquired model 35SX. It was just a recap […]
polishvito wrote on 2023-03-08, 14:19:I have two 1.44mb ALPS drives and can’t get either to work. Both had ugly capacitor leakage One ended up having some torn pads on the motor board so that one is hopeless.
The other the LED lights up and the disc spins, but no movement from the heads whatsoever. The worm shaft moves easily so not seized up. I even tried switching the motor and controller board with the other drive just to see but no difference. I’ve spent way too much time trying to get these to work but I’m still annoyed and don’t know where else to go when the head assembly won’t even try to move.
I just recently repaired an ALPS drive (DFP723D33A, 34 pin, media-sense) on my recently acquired model 35SX. It was just a recap and cleaning job, essentially, and now the drive works perfectly.
Couple things to check. Like previous poster said, there might be corrosion from the electrolyte on the traces so it might prevent the drive from working. Another thing to note is that electrolyte is conductive, so if you havent't cleaned that crap from the PCB, it may short some stuff and drive doesn't work because of that.
Torn pad isn't necessarily a deal breaker. In fact, I managed to tear one during my recap work due to my mistake: I didn't want to use hot air for desoldering (so much plastic and rubber near the capacitors) so I went with a twisting method and screwed up with one cap. However, it was relatively easy to trace from the pad to the next SMD resistor and I just soldered the new cap to that point. One thing I almost missed before starting the recap is that in my drive there are three bi-polar capacitors on the motor board. "Normal" polarized electrolytic caps won't work there, but this should not affect the head movement at all, naturally. But your drive might be of a different type and there may be bi-polar caps on the control side too, so check that you have used correct caps. If you replaced bi-polar caps with polarized ones, that may cause the problem.
Also, I specifically used electrolytic caps as replacement, like the originals were. Reason is that I wanted to be sure that the drive works after recap 100%. Changing cap type to tantalum or ceramic changes capacitor ESR dramatically to lower value and I have no clue how sensitive that circuit is for ESR. So, to be sure that circuit still has 100% identical specs after recapping, I went with electrolytic caps.
One thing worth checking is the possible ribbon/flat flex cables. They might have fractures and that might be the reason why yours isn't working.
So we must be talking about the same drive models. Mine also had those three nonpolarized capacitors - I actually started replacing them with polarized ones before I caught myself and had to order a bag of nonpolarized.
I used electrolytic caps as well. I did through hole ones on the motor board because I find those easier to work with. Used surface mount cans for the controller board because the space in there was so tight.
I guess I'm presuming that the head movement comes primarily from the controller board, is that right? Just trying to see what I could focus my attention on.
I tried to clean up corrosion as much as I could. Short of trying to resolder/reflow every single little component on the board (which I refuse to do) I don't even know where to direct my energy. Hard /impossible to follow all the traces, especially when they go under the disk motor.
Have you found schematics for these drives? I tried searching but couldn't find this particular model. Same exact two drives that came out of a model 30-286 and a model 55.
Oh and I verified the cables (and the on board floppy controller) work with other floppy drives
polishvito wrote on 2023-03-09, 20:52:The IMD alignment test does nothing - all question marks and don’t hear the heads moving at all
If the direction signal is somehow stuck at one logic level the drive might think all step commands are trying to move the head back, and it will not allow that past track 0. That can be tested - move the head forward by rotating the worm screw with your finger (when power is off). Head should either return on power-on or at least move when IMD tries to seek to track 0. No movement = PCB or IC damaged due to corrosion.
At least the spindle works, correct? And doesn't stop by itself after a few seconds when IMD is running aligment test? That would mean the index pulses are coming through at least.
BTW which motor(s) did you swap with the other drive? Spindle or head positioning? Or both? Even undoing the screws on the positioning motor will rotate it a bit and cause the heads to be misaligned, so the drive won't read now - even the track the heads are stuck at now. Once you get the heads to move you will need to realign the drive, and for that you'll need a scope, steady hands and patience. You can get it somewhat working just with IMD alone but it'll never be perfect and might not read some floppies (or other drives might not be able to read floppies written by this one).
polishvito wrote on 2023-03-09, 21:07:So we must be talking about the same drive models. Mine also had those three nonpolarized capacitors - I actually started replac […]
So we must be talking about the same drive models. Mine also had those three nonpolarized capacitors - I actually started replacing them with polarized ones before I caught myself and had to order a bag of nonpolarized.
I used electrolytic caps as well. I did through hole ones on the motor board because I find those easier to work with. Used surface mount cans for the controller board because the space in there was so tight.
I guess I'm presuming that the head movement comes primarily from the controller board, is that right? Just trying to see what I could focus my attention on.
I tried to clean up corrosion as much as I could. Short of trying to resolder/reflow every single little component on the board (which I refuse to do) I don't even know where to direct my energy. Hard /impossible to follow all the traces, especially when they go under the disk motor.
Have you found schematics for these drives? I tried searching but couldn't find this particular model. Same exact two drives that came out of a model 30-286 and a model 55.
Oh and I verified the cables (and the on board floppy controller) work with other floppy drives
Yeah, I used through hole caps for the bipolar stuff, because I had those at hand, SMD elsewhere.
I didn't find documentation for the drive, although I didn't try to search that much. But I noticed the fact that there is very little available information about this particular drive and I assumed that it is one of the rarer models IBM used. I think it is pretty safe to say that if there is no documentation on Ardent Tool, they don't exist. But to me the layout of the drive looks like you said: you have the motor board which attaches with a short ribbon cable to "main" board, which again has the power circuitry and head control functions. In fact, I'm pretty confident about this because when I put the drive back together, I forgot to attach the ribbon cable connecting the motor board. When I powered on the computer, drive heads moved, but obviously motor didn't turn at all and I got a drive error. I didn't do any extra reflow either, I just used good amount of IPA and brushed the boards. In the end it was pretty much very normal recapping job for me.
So, it sounds like basically you should be good to go. I don't think you should be too worried about the motor board "upper" side: it shouldn't affect the heads and I find corrosion damage very unlikely there. I'd say pretty confidently that the problem is on the main board or then the stepper motor is toast, which I think is still more unlikely of these two.
You could post a close up photo or two of the control board, I could check it out if I spot something unusual compared to my drive.
CharlieFoxtrot wrote on 2023-03-09, 22:08:Yeah, I used through hole caps for the bipolar stuff, because I had those at hand, SMD elsewhere. […]
polishvito wrote on 2023-03-09, 21:07:So we must be talking about the same drive models. Mine also had those three nonpolarized capacitors - I actually started replac […]
So we must be talking about the same drive models. Mine also had those three nonpolarized capacitors - I actually started replacing them with polarized ones before I caught myself and had to order a bag of nonpolarized.
I used electrolytic caps as well. I did through hole ones on the motor board because I find those easier to work with. Used surface mount cans for the controller board because the space in there was so tight.
I guess I'm presuming that the head movement comes primarily from the controller board, is that right? Just trying to see what I could focus my attention on.
I tried to clean up corrosion as much as I could. Short of trying to resolder/reflow every single little component on the board (which I refuse to do) I don't even know where to direct my energy. Hard /impossible to follow all the traces, especially when they go under the disk motor.
Have you found schematics for these drives? I tried searching but couldn't find this particular model. Same exact two drives that came out of a model 30-286 and a model 55.
Oh and I verified the cables (and the on board floppy controller) work with other floppy drives
Yeah, I used through hole caps for the bipolar stuff, because I had those at hand, SMD elsewhere.
I didn't find documentation for the drive, although I didn't try to search that much. But I noticed the fact that there is very little available information about this particular drive and I assumed that it is one of the rarer models IBM used. I think it is pretty safe to say that if there is no documentation on Ardent Tool, they don't exist. But to me the layout of the drive looks like you said: you have the motor board which attaches with a short ribbon cable to "main" board, which again has the power circuitry and head control functions. In fact, I'm pretty confident about this because when I put the drive back together, I forgot to attach the ribbon cable connecting the motor board. When I powered on the computer, drive heads moved, but obviously motor didn't turn at all and I got a drive error. I didn't do any extra reflow either, I just used good amount of IPA and brushed the boards. In the end it was pretty much very normal recapping job for me.
So, it sounds like basically you should be good to go. I don't think you should be too worried about the motor board "upper" side: it shouldn't affect the heads and I find corrosion damage very unlikely there. I'd say pretty confidently that the problem is on the main board or then the stepper motor is toast, which I think is still more unlikely of these two.
You could post a close up photo or two of the control board, I could check it out if I spot something unusual compared to my drive.
Attached a photo - try not to laugh too hard at amateur soldering
polishvito wrote on 2023-03-10, 13:29:Attached a photo - try not to laugh too hard at amateur soldering
I don’t think that is bad at all. It just looks messy because of the through hole caps used, but it is same for me. Solder joints look just fine!
I think you should take a photo of the control board, because problem is there most likely. If your motor spins fine when you insert your disk, we can skip this board for sure. At least for now. And this board looks totally fine, I see zero corrosion and it infact looks to be in better shape than mine: solder joints near the caps all got this dull matte finish due to electrolyte corrosion, but yours look bright and clear.
As some previous poster said, you could try to position the head manually by turning the screw to some other location and check if the head moves at all as it should adjust to track 0 or if it is completely dead. Also, even though you can move wormdrive with your finger, there might be too much resistance for the motor. You have probably cleaned and oiled the wormdrive, but also do the same with the rail on the bottom, if you haven’t already.
polishvito wrote on 2023-03-10, 13:29:Attached a photo - try not to laugh too hard at amateur soldering
I re-read your posts and looking at the photo you sent, I think you may have not recapped the control board at all, or at least that’s how it seems. And most likely there lies the reason why your heads wont move. Caps onthe control side are towards the top of the drive and not visible from bottom. So you need to remove control board, and it is easy: pull that white ribbon cable towards the motor spindle to detach it from control board. After that, you need to disconnect the flat flex cable from top side and back of the drive and unplug the electric conector from the back. After that, the controller board is just attached with two screws.
See my drive disassembled before the recap:
There are four caps on the board, which needs to be changed. They are all 10uf 16V, none of them is bipolar.
386_junkie wrote on 2016-01-25, 11:42:Success! […]
Success!
After installing the drive back in with a floppy inserted at boot... the cat no longer had it's tongue and it wouldn't stop talking, happily chirping away with the reference disk! 😁
Good times! 😀
P.S. If anyone is in the same situ, let me know and I can help those wishing to restore their drive.... it beats $50+ for another one!
All the images are gone, I'm in the same situation in that I have this drive type, although someone had already pulled the caps. And I think they may have damaged the board too 🙁
Im assuming 12v(++) 10uf for all the caps?
