Unsticking a Seagate ST-419 head

[Mike Stein]

I've got several ST251-1s that spin up just fine, no funny noises, but then do a bunch of back-and-forth seeks and shut down again. 

It's the usual, "they worked fine the last time;" any ideas what the problem is and if there's anything that can be done? Presumably it's having trouble finding the sync track; weak signal? Any ideas?

m

----- Original Message ----- 
From: "Al Kossow" <aek at bitsavers.org>
To: <cctalk at classiccmp.org>
Sent: Thursday, October 20, 2016 12:23 PM
Subject: Re: Unsticking a Seagate ST-419 head


> The two disks this morning went much better. I tried using a heat gun on the outside of the hda and VERY
> gently freed the heads and got the spindle to turn. Then I pulled the top board and coaxed the spindle motor
> back up to speed. The root disk read without errors, usr has a consistent 28.
> 
> The same experiment didn't work on the usr disk from the first system though :-(
> 
> At least now I have a good root image and probably usuable usr
> 
> 
> 
>> On 10/20/16 2:05 AM, jim stephens wrote:
>>> I actually years ago unstuck drives by removing them, hooking them to cables long enough to allow me to have access to
>>> them external to the system with power, and just holding them in the air and giving them a sharp twist around the axis
>>> of the drive.  That was enough to unstick most.
>>
>