18 Mar
2005
18 Mar
'05
10:13 a.m.
Hello,
I have two RK05J drives, both exhibiting the same problem.
They are *not* currently connected to a system. I have them on the bench
cleaning them up and getting them ready to connect to a PDP 8/e system after
a long period of storage.
There is the I/O terminator card installed in the proper slot in the drive
electronics backplane.
When the drives are powered up, the "power" and "load" lights are on,
and
the door release is activated so that the door can be opened and a disk pack
inserted. However, the blower motor that provides the air circulation for
the drive never starts up. I've checked both blower motors to assure that
they are not seized, and the both spin very freely. I traced the power
wires from the blower motor to a barrier strip, where I checked for
110V AC power, and there's nothing there. So, somewhere in the
circuitry, something isn't right. Any ideas?
Thanks,
Rick Bensene
The Old Calculator Web Museum
http://oldcalculatormuseum.com
18 Mar
18 Mar
3:07 p.m.
Is there a safety lock switch (perhaps on the back) that is normally
activated when installed in a rack that is not activated now while it is on
the bench?
Thanks,
George Wiegand
Vintage Data General Computer Hobbyist
----- Original Message -----
From: "Rick Bensene" <rickb at bensene.com>
To: <cctech at classiccmp.org>
Sent: Friday, March 18, 2005 10:13 AM
Subject: RK05 Help
Hello,
I have two RK05J drives, both exhibiting the same problem.
They are *not* currently connected to a system. I have them on the bench
cleaning them up and getting them ready to connect to a PDP 8/e system
after
a long period of storage.
There is the I/O terminator card installed in the proper slot in the drive
electronics backplane.
When the drives are powered up, the "power" and "load" lights are on,
and
the door release is activated so that the door can be opened and a disk
pack
inserted. However, the blower motor that provides the
air circulation for
the drive never starts up. I've checked both blower motors to assure that
they are not seized, and the both spin very freely. I traced the power
wires from the blower motor to a barrier strip, where I checked for
110V AC power, and there's nothing there. So, somewhere in the
circuitry, something isn't right. Any ideas?
Thanks,
Rick Bensene
The Old Calculator Web Museum
http://oldcalculatormuseum.com
_____________________________________________________
This message scanned for viruses by CoreComm
3:39 p.m.
AFAIK, the RK05 will not function without a controller attached. There are
motor control relays which provide power to both the blower and the spindle
motor and will likely not engage until the power supplies are valid, ACLO
and DCLO are inactive, etc.
--tom
At 03:07 PM 3/18/2005 -0500, George Wiegand wrote:
Is there a safety lock switch (perhaps on the back)
that is normally
activated when installed in a rack that is not activated now while it is on
the bench?
Thanks,
George Wiegand
Vintage Data General Computer Hobbyist
----- Original Message -----
From: "Rick Bensene" <rickb at bensene.com>
To: <cctech at classiccmp.org>
Sent: Friday, March 18, 2005 10:13 AM
Subject: RK05 Help
Hello,
I have two RK05J drives, both exhibiting the same problem.
They are *not* currently connected to a system. I have them on the bench
cleaning them up and getting them ready to connect to a PDP 8/e system
after
a long period of storage.
There is the I/O terminator card installed in the proper slot in the drive
electronics backplane.
When the drives are powered up, the "power" and "load" lights are on,
and
the door release is activated so that the door can be opened and a disk
pack
> inserted. However, the blower motor that provides the air circulation for
> the drive never starts up. I've checked both blower motors to assure that
> they are not seized, and the both spin very freely. I traced the power
> wires from the blower motor to a barrier strip, where I checked for
> 110V AC power, and there's nothing there. So, somewhere in the
> circuitry, something isn't right. Any ideas?
>
> Thanks,
> Rick Bensene
> The Old Calculator Web Museum
> http://oldcalculatormuseum.com
>
>
>
>
> _____________________________________________________
> This message scanned for viruses by CoreComm
> 
4:15 p.m.
I agree with Tom's statements. I had two RK05s that I messed with
standalone for a while and things did not seem to work properly.
When I cabled them up to the RK11D in the PDP-11, everything
was fine and they worked perfectly. I may have had the exact same
problem that you describe when I tried to test things with
standalone drives. Motors didn't run, etc. until the drive was
properly attached to a valid controller (in my case RK11D).
If you really get stuck and need to see what controls
supplying power to the blower, RK05J engineering drawings
are on bitsavers at:
http://www.bitsavers.org/pdf/dec/disc/RK05J_schem_Mar78.pdf
Ashley
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org]On Behalf Of Tom Uban
Sent: Friday, March 18, 2005 3:40 PM
To: General Discussion: On-Topic and Off-Topic Posts; General
Discussion: On-Topic and Off-Topic Posts
Subject: Re: RK05 Help
AFAIK, the RK05 will not function without a controller attached. There are
motor control relays which provide power to both the blower and
the spindle
motor and will likely not engage until the power supplies are valid, ACLO
and DCLO are inactive, etc.
--tom
At 03:07 PM 3/18/2005 -0500, George Wiegand wrote:
in the drive
Is there a safety lock switch (perhaps on the
back) that is normally
activated when installed in a rack that is not activated now
while it is on
the bench?
Thanks,
George Wiegand
Vintage Data General Computer Hobbyist
----- Original Message -----
From: "Rick Bensene" <rickb at bensene.com>
To: <cctech at classiccmp.org>
Sent: Friday, March 18, 2005 10:13 AM
Subject: RK05 Help
> Hello,
>
> I have two RK05J drives, both exhibiting the same problem.
> They are *not* currently connected to a system. I have them
on the bench
cleaning
them up and getting them ready to connect to a PDP 8/e system
after
> a long period of storage.
>
> There is the I/O terminator card installed in the proper slot > electronics backplane.
>
> When the drives are powered up, the "power" and "load" lights
are on, and
> the door release is activated so that the
door can be opened
and a disk
pack
> inserted. However, the blower motor that provides the air
circulation for
> the drive never starts up. I've checked
both blower motors
to assure that
> they are not seized, and the both spin very
freely. I traced
the power
> wires from the blower motor to a barrier
strip, where I checked for
> 110V AC power, and there's nothing there. So, somewhere in the
> circuitry, something isn't right. Any ideas?
>
> Thanks,
> Rick Bensene
> The Old Calculator Web Museum
> http://oldcalculatormuseum.com
>
>
>
>
> _____________________________________________________
> This message scanned for viruses by CoreComm
>
19 Mar
19 Mar
4:46 p.m.
New subject: VaxStation parts needed
54-19288 (-01) SCSI/FDI adapter
4MB DSIMM
Please contact me off-list
TIA,
Glen
0/0
18 Mar
18 Mar
6:53 p.m.
Hello,
I have two RK05J drives, both exhibiting the same problem.
They are *not* currently connected to a system. I have them on the bench
cleaning them up and getting them ready to connect to a PDP 8/e system after
a long period of storage.
There is the I/O terminator card installed in the proper slot in the drive
electronics backplane.
When the drives are powered up, the "power" and "load" lights are on,
and
the door release is activated so that the door can be opened and a disk pack
inserted. However, the blower motor that provides the air circulation for
the drive never starts up. I've checked both blower motors to assure that
they are not seized, and the both spin very freely. I traced the power
wires from the blower motor to a barrier strip, where I checked for
110V AC power, and there's nothing there. So, somewhere in the
circuitry, something isn't right. Any ideas?
IIRC one of the 2 relays on top of the PSU chassis (rear left) controls
the blower, the other one controls the spindle. And the blower relay is
controled by one of the pwoer fail signals.
You'll need the prints, of course, but that might give you a place to
start looking.
-tony
22 Mar
22 Mar
7:26 p.m.
OK, some time back I wrote about a couple of RK05J drives that I have, which
were
connected up to a PDP 8/e, via RK8E.
A few folks wrote back and said that the drive had to be connected to a
controller
to come up. Not so. It won't "READY" a disk, but it has enough brains
locally
to fire up the blower motor, light the LOAD light, unlock the drive door to
allow
a cartridge to be put in, and once a cart is inserted, allows it to be spun
up, but
the heads will never load and the drive will never go READY without the
controller
attached.
Last time everything was powered up (over a year ago), though I was having
problems
with the RK8E, the drives worked fine. They powered up, blower motors ran,
and you
could load a cartridege, spin it up, and the drive would go ready. I could
issue seeks
and reads and writes...but there'd be data errors when doing so, as it
appears that
there's a stuck bit somewhere in the RK8E. All that aside, it's been a
little over a year,
and I've pulled the machine out of storage and am in the process of trying
to get
it back into running condition.
The 8/e seems happy. I powered it up over a long period of time with a
Variac,
watching the main supply voltages come up, and all went well. The 2 4K core
planes seem to be fine, and the 16K solid state RAM board also seems fine.
I can exam/deposit stuff, toggle in small programs (light chasers, etc.),
and
they work fine, and reliably over time.
The problem is the RK05's.
I've disconnected them from the RK8E, have installed the terminator card in
one
drive. I power it up, and the blower motor doesn't start. But, the POWER
and LOAD
lights light up on the front panel, and the drive door unlocks with a clunk.
I've checked all the power supply voltages (+15, -15, +5) under load, and
they
all are within spec, with minimal ripple.
The "CONTROL & INTERLOCK" board in the electronics package in the drive
has the circuitry that controls the blower motor. There is a "safety" relay
which gets pulled in when all of the DC power supplies are good, which
is done by some circuitry on this board. The result is a "DC OK" signal,
which
is active when the drive is powered up. A derivative of this signal drives
a driver that energizes the "Safety Relay", which has multiple contacts.
One set of contacts applies power to the blower motor, and others do things
like dump the charge in
the NiCd battery pack into the head windings to do the emergency head
retract when power dies. I've traced the circuitry from the DC OK signal
generated on the CONTROL & INTERLOCK board, all the way through the
harnesses
and to the relay, and from the relay to the motor, and all are healthy.
The safety relay does pull in as expected when he unit is powered up.
However, the blower motor will not run. I've checked
the relay contacts...they are fine. 120VAC is present on two of the
three wires that go into the blower motor. There is a 5uf motor start
capacitor that, from what I can tell, seems fine. But...the motor
doesn't spin. The funny part is that both RK05's act this way.
I'm puzzled. The motors aren't seized -- they spin very freely.
I've put an ohmmeter across the windings of the motor and there
are no shorts or opens.
I'm really stumped! Could the start capacitor be bad? I don't know
much about how these types of AC motors work. I swapped the start
capacitor with one from another "parts hulk" drive that I have, and
it didn't make any difference.
Any ideas, anyone?
Rick Bensene
The Old Calculator Web Museum
http://oldcalculatormuseum.com
7:37 p.m.
a cartridge to be put in, and once a cart is inserted,
allows it to be spun
up, but
the heads will never load and the drive will never go READY without the
controller
attached.
Are you sure? It's been a long time since I've done this, but I thought
an '05 would load the heads without a controller connecteed, provided
there's a pack installed, power is good, etc.
The safety relay does pull in as expected when he unit
is powered up.
OK, so far, so good.
However, the blower motor will not run. I've
checked
the relay contacts...they are fine. 120VAC is present on two of the
three wires that go into the blower motor. There is a 5uf motor start
capacitor that, from what I can tell, seems fine. But...the motor
doesn't spin. The funny part is that both RK05's act this way.
I'm puzzled. The motors aren't seized -- they spin very freely.
I've put an ohmmeter across the windings of the motor and there
are no shorts or opens.
I'm really stumped! Could the start capacitor be bad? I don't know
Could well be. It's actually a 'run' capacitor I think (there's no
starting relay for the blower motor).
Baiscally, the motor has 2 windings. One is directly across the 120V AC
input. The other has the capacitor in series, 120V AC across the lot. The
result is that the currents in the 2 windings are not in phase with each
other (due to the capacitor in series with one of them). These windings
magnetise alternate poles in the motors stator, so you get 2 out-of-phase
magnetic fields in the stator, which appears a a 'revolving' magnetic
field. In effect the rotor is dragged round by this field (yes, this is
a simplification, but it should give an idea as to what's going on).
much about how these types of AC motors work. I
swapped the start
capacitor with one from another "parts hulk" drive that I have, and
it didn't make any difference.
Any ideas, anyone?
What I would do now :
Remove a blower (disconnect the 3 leads at the barrier strip, undo the 4
allen-head screws hoding it in place, take it out.
Strip it down. THe ring round the intake comes off by some self-tapping
screws under the foam. Then the impeller comes out by undoing the
setscrew. Then a coupleof nuts to hold the motor to tbe blower housing.
The motor also comes aaprt (4 little metal clips). Pull out the rotor and
bearings.
Look at the windings. Damaged insulation is, alas, common on these
motors. Shorted turns will mess things up, alas.
It's then put the motor back together and wire it up on the bench with
the staring capapcitor. Try powering it up. Measure the voltages across
the 2 windgs (one should be 120V, the other somewhat less due to the
capacitor, but certainly not zero).
Try a new capacitor if you can get one. Capacitors do go off, even when
not in use.
-tony
24 Mar
24 Mar
12:59 p.m.
Well, as Tony surmised, the blower motor itself was bad. The odd part
is that there were two RK05's in the system, and both of the blower motors
were toast. I'm wondering if there was something environmental about the
storage (dry, insulated/sheetrocked garage, but no heat) that did something
to the motors that caused them to die in both drives. I took the blower
motor
from the parts drive, and it was fine. It was made by
a different
manufacturer,
and seemed much more robust. I now have one drive that will work.
I'm hoping that I can, with the procedure Tony mentioned for tearing
the motors down, perhaps cobble together another motor, or perhaps take
the motor to a motor repair place and see if the windings can be repaired.
It's interesting that in order to remove the blower motor, you have
to destroy the foam seal that seals the motor to the electronics bay, in
order
to get to the fourth allen head cap screw that secures the motor to the
drive
base. I have to improvise and make my own new foam filter I put the good
motor back in the drive.
The 2nd drive, as it turns out, also had the upper head crashed at some
point in time, it has a lot of oxide on it, and shows signs of getting hot,
so to get
that 2nd drive running (once the blower motor issue is resolved), I'll
have to replace the top head. My question now is, do the heads have
to be replaced in sets, or can one head be replaced? Once a head is
replaced,
does the drive have to be aligned in any way? I've read the head
replacement
procedure, and it suggests it, but I don't have an RK05 alignment pack,
which
pretty much precludes doing that. Is there a chance that just replacing the
head, being careful to make sure it is properly seated and that the torque
on the holddown set screws is correct, that the drive will "just work"?
I have a good set of heads from the 'scrap' drive.
By the way, an RK05 drive will indeed load the heads, go READY and give
"ON CYL" status with no controller connected, so long as the terminator
is installed in the last slot of the electronics backplane in the drive, and
a good cartridge is installed.
Now that I have one drive that seems healthy, the next step is to figure
out what is going on with the RK8E...it seems that one bit in all reads
from the drive is stuck on. Probably a bad bus driver,
I hope.
Rick Bensene
The Old Calculator Web Museum
http://oldcalculatormuseum.com
7:48 p.m.
Well, as Tony surmised, the blower motor itself was bad. The odd part
is that there were two RK05's in the system, and both of the blower motors
were toast. I'm wondering if there was something environmental about the
storage (dry, insulated/sheetrocked garage, but no heat) that did something
The insulation on those motors is not brilliant to say the least. We have
particular problems over here, because it has to stand 240V -- the motoe
may only have 120V between the ends of its windings, but there's 240V
bwetween one end and chassis ground when the drive is set for 240V mains.
I've had the darn things catch fire.
Do you have a megger? If so, I'd stick it on the dead motors (windings to
frame) and see what happens.
to the motors that caused them to die in both drives.
I took the blower
motor
from the parts drive, and it was fine. It was made by a different
manufacturer,
and seemed much more robust. I now have one drive that will work.
I'm hoping that I can, with the procedure Tony mentioned for tearing
the motors down, perhaps cobble together another motor, or perhaps take
the motor to a motor repair place and see if the windings can be repaired.
The bad news is that the stator laminations are spot-welded into the
case, and only one end plate is removeable. Rewinding that would be an
'interesting' project, therefore.
It's interesting that in order to remove the blower motor, you have
to destroy the foam seal that seals the motor to the electronics bay, in
order
to get to the fourth allen head cap screw that secures the motor to the
drive
I seem to rememeber there is a way to get a tool onto that screw, maybe
you need a ball-ended allen key or something, which can be used at an
angle. Or maybe you can just push a normal key past the foam, and if the
latter is in good condition (which it won't be now), it'll just deform
out of the way.
base. I have to improvise and make my own new foam
filter I put the good
motor back in the drive.
FWIW, taht foam seal is not essential by any means. I've run plenty of
drives without it.
The 2nd drive, as it turns out, also had the upper head crashed at some
point in time, it has a lot of oxide on it, and shows signs of getting hot,
so to get
that 2nd drive running (once the blower motor issue is resolved), I'll
You may have to replace it, it may just need a really good clean (I've
heard that even quite badly mangled heads will clean up anf fly again).
have to replace the top head. My question now is, do
the heads have
to be replaced in sets, or can one head be replaced? Once a head is
You can replace a single head. Of ocurse you replace the assembly (head,
spring leaf, mounting block), but you don't need to replace the other
head as well.
replaced,
does the drive have to be aligned in any way? I've read the head
Yes. In fact if you remove a head you need to do the alignment even if
you put the same head back in again.
replacement
procedure, and it suggests it, but I don't have an RK05 alignment pack,
which
pretty much precludes doing that. Is there a chance that just replacing the
head, being careful to make sure it is properly seated and that the torque
on the holddown set screws is correct, that the drive will "just work"?
It'll work, but you won't be able to use the packs in any other drive, or
vice versa (this is, of course, an 'interchangeability adjustment' -- a
drive with misaligned heads will read its own packs).
There are 2 screws for each head. One clamps the head tail into the
positioner carriage. The other forces the head forwards as you screw it
in. The procedure is to loosen the first one, back out the second one,
push the head as far into the positioner as you can, then with the
alignment pack loaded, slowly screw in the second one until the head is
aligned. Clamp up the first one, then back out the second one a bit
(it'll have no effect), to prevent it moving the head later due to
thermal expansion, etv.
Therefore, if you then remove the head you haven't a hope of getting it
back in the right place without an alignment pack.
I have a good set of heads from the 'scrap'
drive.
By the way, an RK05 drive will indeed load the heads, go READY and give
"ON CYL" status with no controller connected, so long as the terminator
is installed in the last slot of the electronics backplane in the drive, and
a good cartridge is installed.
Thought so. By 'good cartridge', all the drive checks for is the sector
pulses from the hub notches. It doesn't matter whart's on the disk
(there's no servo, or clcok track, or anything like that).
-tony
7036
days inactive
7043
days old
9 comments
6 participants
participants (6)
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acme＠gbronline.com -
ard＠p850ug1.demon.co.uk -
ICS＠Core.com -
rickb＠bensene.com -
uban＠ubanproductions.com -
wacarder＠usit.net