RL02 Question

[allison]

On 03/27/2018 05:34 AM, Aaron Jackson wrote:
>> On 03/26/2018 04:08 PM, Aaron Jackson via cctalk wrote:
>>>>> So, from what I can see, the drive should spin up correctly, but for
>>>>> some reason it goes into fault mode. I am right in thinking that upon
>>>>> load, the heads should continue moving forward until the first track is
>>>>> found, right? I should not have to perform a seek manually from the PDP?
>>>>> If this is not the case, perhaps there is something else wrong.
>>>> I’m not an RL02 hardware expert at all, just a daily user back in the
>>>> day. I’m reading this assuming that at all times the drive is
>>>> correctly hooked up to an RLV12 in a running PDP with the correct
>>>> cable and termination present on the drive? If it isn’t you’ll get a
>>>> fault condition instead of ready after spin up.
>>>>
>>>> A
>>> No worries, your input has been valuable, so thank you.
>>>
>>> For anyone else who might have an idea:
>> ON fault the heads are retracted and will not load till cleared.
>> Least mine behaves that way.
>>
>> Most common problems are wrong drive address, cable issues, no terminator.
>> Others include head lock not removed or the auto unlock style of
>> headlock has
>> the tab broken.
>>
>>> It seems to be hooked up correctly. When it is in the weird flashing
>>> ready state, the boot loader says "Read error" or "Device error"
>>> randomly. The heads oscillate back and forth very slightly as if it is
>>> trying to align itself better on the first track, which doesn't exist
>>> because it hasn't moved far enough into the pack.
>> IF in fault its resetting to retracted on every try.
>> If not something else is wrong.
>>
>>> I'm beginning to think the heads are bad which will be far too expensive
>>> so I may end up giving up.
>> Heads are not that expensive... However you could have a wrong pack
>> or one that has been erased and has no servo tracks. You must start with
>> a known good pack and cleaned heads.
>>
>>
>> Allison
> Thanks for the suggestions, Allison.
>
> Given that the pack was tested before it was shipped, I am beginning to
Did it survive shipment?  Common problem.

> come to the conclusion that the heads are bad. I can see the servo burst
> data if I push the heads on a few mm further into pack, but perhaps the
> heads produce noise which confuse the logic upon load.
Not likely the heads produce noise they are passive.  If there is a loose
or broken wire maybe and thats easily checked with an ohm meter.

However... If you push the heads in you see servo burst that suggests a
alignment or servo system problem.  Its supposed to seek and find the
servo info.

Heads fail only a few ways.  Broken wires, crashed with mechanical damage,
and open windings.  They are remarkably simple other than mechanically
precise.

> Heads are more expensive than what I'd like, from what I have seen on
> eBay.
Cant help that.
> I believe I have a "working" (i.e. non-crashing) down head (as in the
> one on top). If this is head 0 (anyone know?) then I might have a chance
> of getting it working without spending anymore money. Let's see.
I'd have to read the RL02 service docs to remember what head is which.
I'
d suggest diagnosing the problem to see if its a servo/mechanical
alignment issue.

Long short story.  I got my RL02 directly through DEC while I was a
engineer there.
It was a pile of parts in the back lab.  The story was it was pulled
from a customer
site as FS could not make it work at install.  Seems despite being new
just about
everything that could be swapped apparently was and no one could get it
to spin
up.   So I made a deal if I get it working its mine (ok, to be part of
the 11/23 in my
office, which later would become mine).   After assembling it and
testing it sure
enough it didn't spin and would turn slowly for a few moments and quit.
  Drag
out the meter and start testing voltages.  I found the motor starting
cap (known
new) had odd voltages.   A bit of ohming out later it was the crimped
faston
connector at the end of the power line going to the capacitor.   What
was wrong
was crimped but the wire was never stripped so there was no connection. 
The
only thing never swapped was the power wiring harness.  The pile of swapped
boards and even heads was impressive.  I got the drive and word got around
that it was me that solved the riddle.  I troubleshot the problem, and
didn't
swap it to death.

Before you swap out a part that is expensive or unobtainium check to be
sure its the problem.

Allison