7 Mar
2014
7 Mar
'14
12:02 a.m.
?
So I put in the RL8A disk controller (M8433) and connected the cable ?
to one of the drives at a time. Also connected the terminator on the ?
drive.
?
The first drive that I tested turned on the "READY" light, then ?
nothing more happened. I was able to open the drive immediately.
That does not sound right. You do mean 'ready' -- the one with the drive?
number on it? ?A Drive should only be 'Ready' when it's spun up to speed,?
the heads have loaded, and the head servo has locked.? ?
How much of this depends on a working controller (RL8A)?
Just about all of it. The drive needs a clock signl from the controller?
even to do things like check the motor is n't truning (which is necessary?
before the cover unlocks). If the clock is missing, the 'Fault' light?
comes on, but of course there are many other causes for this.
It's been some yers since I've been isnde an
RL, but I would start by?
checkign all the indicator bubls (you do not want to be getting false?
information becuase of a burned-out bulb!). Then, IIRC, the 'Fault' lamp?
is drven by the logic OR of a lot of signals (I seem to revcall active?
low signals and a '30 NADN gate here). If the Fault light is on, then see?
whic signal(s) is asserted, and trace back from there.
I will check the bulbs and then check what errors that have been asserted.
/Anders
7 Mar
7 Mar
7:39 a.m.
On Fri, Mar 7, 2014 at 3:02 AM, <anders at abc80.net> wrote:
>> So I put in the RL8A disk controller (M8433)
and connected the cable
>> to one of the drives at a time. Also connected the terminator on the
>> drive.
>>
>> The first drive that I tested turned on the "READY" light, then
>> nothing more happened. I was able to open the drive immediately.
That doesn't sound right. IIRC, There is supposed to be a second or
two from power-on to the solenoid clicking that unlocks the lid.
>> How much of this depends on a working
controller (RL8A)?
>
> Just about all of it. The drive needs a clock signl from the controller
> even to do things like check the motor is n't truning (which is necessary
> before the cover unlocks). If the clock is missing, the 'Fault' light
> comes on, but of course there are many other causes for this.
Yep.
About the cover, when should it be unlocked? Is it
open when the power is
off (I suspect that it should be locked)?
The cover should be unlocked when the drive is powered on and
"notices" the disk is not spinning. It should be locked when the disk
is spinning (including spin-up and spin-down) and when the drive is
powered off.
The thing is that the cover is always unlocked on one
of the drives, on the
other drive it seams like it's locked when the power is off.
The other drive is "normal".
> It's been some yers since I've been isnde
an RL, but I would start by
> checkign all the indicator bubls (you do not want to be getting false
> information becuase of a burned-out bulb!).
It's common for used drives to be missing bulbs or have burned out
bulbs. Since I rarely use write-protect, that's the one I borrow when
I need one "right now". I never borrow the fault bulb.
-ethan
1:06 p.m.
Yes, the white indicator with either a "0"
or a "1" on it! It didn't
feel right.
That is totally wrong. No way should a drive be 'ready' at power-up.
Soundsl ike a logic problem for sure.
About the cover, when should it be unlocked? Is it open when the power
is off (I suspect that it should be locked)?
The thing is that the cover is always unlocked on one of the drives,
on the other drive it seams like it's locked when the power is off.
The only time the cover is unlocked is when the drive knows rthe heads
are retrcted and the spindle is stopped. So it is locked when the drive
is not powered
The cover is loced by a little soenoid on the underside of the palte at
the back corner of the disk cartrige housing. On older drives it also
carries the brushes that sweep dsst onto the disk :-). More seriously, if
the drive is unlocked wven when uynpowered, you have a mechncial proble,
Eitehr the solenoid is sticking, or there's a problkem with the lock
slider, or...
-tony
2:51 p.m.
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk
To: <cctalk at classiccmp.org
Sent: Friday, March 07, 2014 9:06 PM
Subject: Re: PDP-8a Restoration/RL01 issues
,
> Eitehr the solenoid is sticking, or there's a problkem with the lock
> slider, or...
The thin wire that connects the lock slider to
the actaul lock runnes in
small plastic cutouts in the lid and on one of my drives was sceased and
held the lock open.
Dave H
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.2247 / Virus Database: 3722/6664 - Release Date: 03/07/14
>
3903
days inactive
3903
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3 comments
4 participants
participants (4)
-
anders＠abc80.net -
ard＠p850ug1.demon.co.uk -
david＠hheng.plus.com -
ethan.dicks＠gmail.com