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PS/2 Floppy Drive Repair

falter

falter

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Jan 22, 2011
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Thought I'd make a separate heading for this.

My Model 70's 1.44mb drive half works - the head moves but the spindle motor doesn't turn. I've read of a few people replacing leaky caps having success at getting these drives going again.. is a leaky SMD cap a likely culprit for no motor?

The second question I have is regarding my Model 30 1.44mb. It works, albeit with some issues. However this aft it kind of jammed up and was making this horrible ratcheting noise while the heads vibrated. I took at look at the internals and noticed there is a sort of corkscrew shaft from the stepper motor that moves the head up and down. At the end closest to the motor is there is a small what looks like brass ring secured by an Allan screw. I noticed this was loose.. Im wondering where that should be locked in and if it is supposed to be a complete ring.. ie. If mine is broken because half is missing.

Many thanks!
 
what's the drive model of your 70 ?
is it an alps ? i have some reason to believe it is...

for the model 30, can you provide a picture of what you talk about ?
 
so, yes, thoses alps drives suffer from capacitors leak.
look at the spindle motor board, there's 2 polarized capacitors near the motor control chip. they are 10 and 4.7µf. and sure they have leaked.

but, there's also another joke they can do... look at the chip solder joints, and i place my bet they are totally oxidized, so badly some joints are not conductive anymore.
and that's why the motor don't spin. so, at minimal, solder joints need to be refreshed, or better, desoldering the chip, and check continuity.
because there's also risks for some pads tracks to be cut.

for the model 30, i ask you picture, because i don't really see what you mean.
i suppose this is a model 30 with a big drive ?
 
Is this the chip you mean, on the ALSP drive? Definitely looks like a few iffy pins there. Darn caps leaks!

https://drive.google.com/open?id=1DTda2OtFwo_Jvi9OLli_9f59vMQBwQYx

I'll have to take a pic of the Model 30 drive the next time I'm using it.. it's installed right now. Maybe I'll take a video. It seems to randomly make abnormal grinding noises and often loses the ability to read known good 1.44MB disks.
 
no doubt than at least the 3 first pin at the right of pin 1 mark need to be at least cleaned and refreshed. pads looks totally oxidized.
and you may check continuity on the very first one on the right on the picture.

this one is directly connected to negative side of the 10µf. this negative point is differential from the main ground, so you can't pick it on the drive chassis to check continuity.
you'll have to pick it directly to the negative side of the capacitor. i'm 95% sure the continuity is gone. and pretty sure the same for the 2 others pin.
the rest i see seems to look good :)
 
I know it's difficult to hear, but if I were working on that, I wouldn't go any further until I pulled that chip off and saw what's underneath it. If a cap has leaked, it's highly likely that there is (or soon will be) further damage on the PWB beneath it.
 
I have replaced the SMD capacitors, at least those on the PCB surrounding the motor, on a couple of these drives. Doing so revived one of the drives however I think I damaged one of the flex cables on the other one. I would be happy to do so, at no cost, for yours if you want to send me the drive or PCBs.
 
if you do it, do the entire drive.
it's not only the 2 polarized near the spindle motor controller, but also thoses on the I/O and power pcb.
sometimes on this pcb, you can also get resistors or coils killed by corrosion, making the stepper motor not working correctly, or not at all.

all is matter on how the corrosion spreaded. sometimes they are easy to fix, sometimes they need "real love" :D
 
whaka said:
if you do it, do the entire drive.
it's not only the 2 polarized near the spindle motor controller, but also thoses on the I/O and power pcb.
sometimes on this pcb, you can also get resistors or coils killed by corrosion, making the stepper motor not working correctly, or not at all.

all is matter on how the corrosion spreaded. sometimes they are easy to fix, sometimes they need "real love" :D
Click to expand...

I'm not sure why I didn't recap the I/O and power PCB. I just spent a couple of hours completely disassembling the drive. Specifically I was interested in replacing the ribbon cable for the read / write heads. I learned a lot doing this, specifically what a PITA it is if you remove the three screws which secure the upper head assembly. I was able to reassemble it however I suspect there is an alignment process that needs to be performed as the upper head assembly doesn't securely lock into position.

It appeared to "function" in a similar manner as before I disassembled it but I used quotations because the drive wasn't functioning before I performed the disassembly. I did this so I can become familiar with what it takes to disassemble the drive. It appears the head assembly can be removed merely by removing the stepper motor which gives you the ability to move the assembly by turning the screw. This will reveal a screw which can then be used to pull off the head assembly.

If I were to do this again I would highly recommend NOT removing the three screws which secure the head assembly. Doing so likely puts it out of alignment and requires removing the stepper motor in order to reassemble it.

I will be replacing the caps on both drives I/O and power PCB boards as neither have been done. Unfortunately the drive which was working is no longer working so I have no functioning floppy drive. Thankfully the system is configured and boots from the hard drive but I can't remove the CMOS battery or that will all change.
 
hmmm yes, upper head never need to be dissasembled. if you're patient, maybe you can get it back to read again.
for realignement of the upper head, you can simply use the lower as reference. when the upper match the exact position of the lower, then you're really near the truth.

but sure if you taken apart the stepper motor too, things get complicated. but patience is often the key for that.

for removing the entire head assembly, you don't need to remove the stepper motor in any way.
you need to move the stepper motor shaft by hand (can be a bit hard sometimes on some drive, but it's doable), till the assembly reach the center of the drive.
then you'll see a screw through a hole in the assembly, letting you loose the head assembly shaft then you can pull it off.
and when the shaft is removed, you can easily remove the heads.

but a picture is always better than 1000 words... :)

 
Last edited:
I've already gone through the complete tear down as I wanted to learn more about how to do it. The drive was non-functional so I figured why not. Today I recapped both drives I/O and power PCBs. Unfortunately no change. I'll buy another one and see what I can put together for a working drive.
 
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