Hello group,
I have a disk ii that has poor down pressure when the door is closed. The drive performs fine (how I don’t know) but there’s clearly no where’s near the pressure you feel when I close all my others. I checked that all the washers are in the hub, and both springs are present. Anyone know how to improve this closing pressure? A better way to describe it is it feels like the hub isn’t giving the down pressure on the disk when the door is closed.
If you have the spring and it's reading I'm not sure why you're questioning this. You really don't want any pressure on the disk it needs to touch but nothing more. There should be no air gap but you wouldn't be able to determine that.
Thanks Jeff,
I’m concerned because it almost feels like the door is going to pop open on its own. I know there’s software that supposedly tests this pressure, I don’t know how accurate the test is but if for some reason it says it’s not acceptable, how would you go about correcting it? Both drive doors on my TRS80 model III are really weak also and feel like their going pop open. I own 25 disk iis and this one clearly is noticeable that something’s not the same as the others and I’m just trying to make it as the others.
So, it sounds like you're equating the door latching with the head pressure, is that correct? The door latch is different than the head and the head is independent of the door at least as far as pressure on the media and felt pad.
If I'm understanding here's what I'm thinking you should investigate....
The door latch is a physical mechanism that when you close the latch the top of the latch slides along tracks on both sides:
IMG_6198.jpg
This is the first half and just the movement while the latch is rotating closed. At the other end, the business end is a metal clip which will slide from the top half, over the opening and to the bottom half:
IMG_6200.jpg
Here's where the magic happens....
The metal clip will side over a "nub" located just under the disk opening slot and this is a "ramp" with a "catch" and why you should feel some resistance when closing and opening as the latch needs to move over the nub:
IMG_6201.jpg
What sometimes happen is the metal clips (one on each side) can get bent out or the nub can ge worn down, but in all likley hood your metal clip has been bent out and may need to be bent back into place.
Interesting you brought that up. Maybe I am mistaking down pressure with those tabs possibly becoming weak. I know the tabs your talking about. Tomorrow I’ll take a look at them. I could probably take an entire door setup off another drive and swap it in and if that’s the issue, that should correct it. Then I’ll know that’s the problem and I can adjust the one with issues. I’ll let you know if that was it.
Yes the head pressure is really a function of the spring which should still be fine under most circumstances.
I'm still a bit unclear how you were observing the head "pressure". Is that really just a speculation based on the way the door works? I'm assuming this is the case and will just move forward expecting the head is not the problem rather the problem is just the door "latching" and "holding" force which hopefully you'll find is the result of those metal clips.
I had some time last night to look at the clips, I initially found a drive that I felt closed properly and I took the face, the door and the entire arm with the hub and put it all in the drive in question. Now it closes only slightly better, no wheres near like it did when it was on the drive I took it off. I'm not going to fuss with it anymore though, it reads and writes fine and it will just be a characteristic of this particular drive I guess. I'll try bending the clips a hair like you suggested but I figured the other door with its original faceplace would have still worked together even though they were in another drive.
Most likely it is just worn out. Is it visibly rounded off or smoother or anything, anywhere there is friction?