Quantum Prodrive possible repair

[Bolle]

The white thing is the parking brake. I think it is supposed to keep the heads locked in the parking position. It should flip over and release the heads once the platters are spinning.

If it doesn’t swing over it must be stuck.

I would check again if it is really not sticking to the rubber bumper. The bumper might still look ok but might already be sticky enough to hold onto the light plastic piece that only moves from the platter airflow. Not a lot of force behind that so not a lot of stickyness is needed to hold it.

 

[bibilit]

I have removed this part from two drives to get them working again.

No issue so far.

 

[Bolle]

Problem is that the heads might move while the platter is still spinning up. Insufficient platter speed means not enough airflow to keep the heads from touching the surface.

I would guess that most drives are smart enough not to move the heads as long as the platter isn’t at full speed but the brake has to be there for some reason.

 

[Brett B.]

The rubber bumper in question is attached to the magnet, correct?  I found one there and it's in good shape.  I understand that there's one under the platter too, but the head doesn't appear to get stuck there and it moves freely as long as it can't get stuck on that parking brake deal.  I will check it again.

 

[Franklinstein]

I posted in this thread about rubber replacement a fairly detailed description of what these bumpers do and where they are on both the ELS and LPS drives. I figure silicone of some sort would be a perfect replacement material for them. You can probably use silicone beads if you can find them; the bumpers don't have to be perfectly cylindrical, just with dimensions in the ballpark of the originals. I'd like to find something made of silicone shaped roughly like a glue stick that I could cut to size.

The "parking brake" is Quantum's AIRLOCK armature. Its function is to prevent the head armature from moving out of the landing zone in the event the drive experiences shock. It utilizes the air current generated by the spinning platters to move the arm out of the way once the drive spins up, and it's spring-loaded to automatically deploy when the drive spins down. You'll notice that in older drives such as the LPS, the lower capacity versions have an odd black plastic platter on top. This is because the air currents required aren't generated without two platters. However, this problem was solved in the newer ELS drives: the single-platter drives have a wicked-looking attachment at the top of the spindle that generates enough air to move the AIRLOCK armature.

The head armature really don't have any torque so the slightest stickiness to any of the bumpers will keep it from moving. Your drives are probably sticking on the bumper underneath the platters (if you use an ELS drive), though if the AIRLOCK armature doesn't move once the platters are at full speed, there could be something unusual causing it to stick.

 

[pinto_guy]

I might have found a solution that does not require removing the voice coil top magnet. I simply use a water hose washer, the flat kind that's usually orange/brown. I cut about a quarter of it, and insert it between the two magnets, in the space directly to the left of the preamp PCB. Somehow the dimensions are just right. This piece of rubber fits snuggly by friction, and it prevents the actuator from touching the gooed crash stop bumper. I "fixed" two drives that way, one single and one double platter, and they both work. See photos below.

 

[corbinq27]

I might have found a solution that does not require removing the voice coil top magnet. I simply use a water hose washer, the flat kind that's usually orange/brown. I cut about a quarter of it, and insert it between the two magnets, in the space directly to the left of the preamp PCB. Somehow the dimensions are just right. This piece of rubber fits snuggly by friction, and it prevents the actuator from touching the gooed crash stop bumper. I "fixed" two drives that way, one single and one double platter, and they both work. See photos below.

View attachment 31955

View attachment 31954

I was poking around on eBay and saw this device:

Quantum ProDrive ELS Repair Insert - Fix your classic Macintosh hard drive! | eBay

This ABS plastic insert corrects the stuck head problem common on Quantum hard drives used in old Macintosh computers from the 80's and 90's. Take care to keep the disk's platter covered. Seat the left side of the insert into place.

www.ebay.com

This looks somewhat similar to your fix.

has anyone tried out one of these devices from the eBay listing? does it work? It would seem to me using a water hose washer would probably be significantly cheaper!

Also, I've seen on some Quantum hard drives that there's a sticky rubber bit under the platters as well. Does that not affect this particular kind of Quantum drive?or does this fix also get around that?

 

[ymk]

has anyone tried out one of these devices from the eBay listing? does it work? It would seem to me using a water hose washer would probably be significantly cheaper!

Also, I've seen on some Quantum hard drives that there's a sticky rubber bit under the platters as well. Does that not affect this particular kind of Quantum drive?or does this fix also get around that?

I make those and they do work. You can check the item feedback.

It prevents contact with the sticky rubber and won't interfere with the parking mechanism.

You don't need to expose the drive internals more than this:

 

[Daniël]

It would seem to me using a water hose washer would probably be significantly cheaper!

You'll have to take off more if not all of the upper cover, increasing the risk of dust contamination, as well as the top head magnet to fit those, which incurs the risk of disturbing the head too much vertically and breaking the drive. So yeah, it is cheaper, but also riskier. Just depends on what you're willing to spend and risk when trying to fix one of these.