24 Apr
2004
24 Apr
'04
5:53 a.m.
A few initial questions after a couple of these beasties turned up at
the museum:
Does anyone have OS install media for these? We've got the manuals, but
no floppies and I'm not sure what state the hard drives are in yet.
Don't suppose anybody has schematics / service information?
Predictably, the batteries inside the machines are toast and have taken
half the circuitry with them (grr!). I'll clean everything up and then
bypass the tracks which have been damaged / eaten away. Presumably
there's a trick to starting these things after battery failure by
feeding power straight to the internal relay - any ideas what voltage it
needs though? And once running will I still need to keep the relay
energised or will the PSU circuitry take over (even in the absence of
batteries - I'm just going to remove the damn things completely)?
I've got one hard drive to spin up and become ready after dumping half a
can of WD40 onto the bottom spindle bearing - it wouldn't even turn
before that. Now it just sounds like a sick cat. :-/
Hopefully it'll last long enough to get any useful data off it though.
I notice what seems to be a SCSI connector on the system board - can I
pull out the ST506 disks and just run a more modern (and hence reliable)
SCSI disk from here? Or is the SCSI connector (if that's what it even
is!) just designed to support a tape drive, and the machine always
expects the boot drive to be an ST506 disk?
cheers
Jules
24 Apr
24 Apr
9:20 a.m.
Hi Jules,
i got that one formTony Duell some times ago :
There's a trick if the machine won't power up
at all...
The power switch on the MG1 is software-controlled (!), and it runs off 5
AA NiCd cells on the power distribution board (these also keep the RTC
running). They're charged when the machine is running, but of course if
you leave it powered-down for too long, they go flat, and you can't turn
it on agaain.
The way round this is to connect a 9V battery (a PP3 or similar) to 2 of
the pins of one of the connectors on the power distribution board (I can
get the exact details). The machine will then power up, and you leave it
running until the NiCds are charged
The connector is J13 ...
Btw: do you have a spare power supply (or maybe some schematics) ? Mine
is dead, so i never got my machine up and running :-(
Bernd
On Sat, 24 Apr 2004 17:53:22 +0000, Jules Richardson wrote:
A few initial questions after a couple of these beasties turned up at
the museum:
Does anyone have OS install media for these? We've got the manuals, but
no floppies and I'm not sure what state the hard drives are in yet.
Don't suppose anybody has schematics / service information?
Predictably, the batteries inside the machines are toast and have taken
half the circuitry with them (grr!). I'll clean everything up and then
bypass the tracks which have been damaged / eaten away. Presumably
there's a trick to starting these things after battery failure by
feeding power straight to the internal relay - any ideas what voltage it
needs though? And once running will I still need to keep the relay
energised or will the PSU circuitry take over (even in the absence of
batteries - I'm just going to remove the damn things completely)?
I've got one hard drive to spin up and become ready after dumping half a
can of WD40 onto the bottom spindle bearing - it wouldn't even turn
before that. Now it just sounds like a sick cat. :-/
Hopefully it'll last long enough to get any useful data off it though.
I notice what seems to be a SCSI connector on the system board - can I
pull out the ST506 disks and just run a more modern (and hence reliable)
SCSI disk from here? Or is the SCSI connector (if that's what it even
is!) just designed to support a tape drive, and the machine always
expects the boot drive to be an ST506 disk?
cheers
Jules
9:34 a.m.
A few initial questions after a couple of these beasties turned up at
the museum:
I have one. I also have schematics, technical notes, and so on.
Does anyone have OS install media for these? We've got the manuals, but
Yes, but on 3.5" (720K) disks. You can put a 3.5" drive in place of the
standard 5.25" 80 cylinder one, at least temporarily, to do an OS install.
no floppies and I'm not sure what state the hard
drives are in yet.
Don't suppose anybody has schematics / service information?
Yes I do, inclduing schematics of the bits that weren't in the oficial
manuals...
Predictably, the batteries inside the machines are toast and have taken
half the circuitry with them (grr!). I'll clean everything up and then
Well known problem. The 0.1" header connector between the power
distribution board and the mainboard often suffers, BTW. Clean things up
with a dilute solution of citric acid, the battery electrolyte is alkaline.
The power distribution PCB is drilled to take the better-grade of AA cell
holders that RS components sell (sold?). Fit those and pop in normal
non-tagged AA NiCds. Easier to replace next time you need to do it.
bypass the tracks which have been damaged / eaten
away. Presumably
there's a trick to starting these things after battery failure by
feeding power straight to the internal relay - any ideas what voltage it
YEs, you connect a 9V PP3 battery to a connector on the power
distribution board. I can look up the exact details.
needs though? And once running will I still need to
keep the relay
energised or will the PSU circuitry take over (even in the absence of
batteries - I'm just going to remove the damn things completely)?
I think you need the batteries to act as a shunt regulator for the RTC
chip. You certainly do on a Torch XXX.
Once you've jump-started the machine, it will stay running even if the
NiCds are totally flat. You can disconnect the 9V battery once it's going.
I've got one hard drive to spin up and become ready after dumping half a
can of WD40 onto the bottom spindle bearing - it wouldn't even turn
WD40 is not really a lubricant!
before that. Now it just sounds like a sick cat. :-/
Hmmm.. I prefer healthy cats...
Hopefully it'll last long enough to get any useful
data off it though.
I notice what seems to be a SCSI connector on the system board - can I
No it's not. It's a 50 pin header that's connected to some of the signals
on the hard disk controller chip (NEC 7261 or something like that -- I
know I have some data on it).
It was going to be used for an SMD interface. Pull out some of the chips
on the mainboard (ST506 buffers, data separator, etc), connect an adapter
board to this connector. Problem was, the DMA controller couldn't keep up
with the SMD data rate, so the adapter was never produced.
Mind you this is the machine where early models have a graphics
'processor' that's bit-serial and actually slower than doing the
operations using the 32016. That's why later machines have lots of empty
IC locations on the mainboard.
pull out the ST506 disks and just run a more modern
(and hence reliable)
SCSI disk from here? Or is the SCSI connector (if that's what it even
is!) just designed to support a tape drive, and the machine always
expects the boot drive to be an ST506 disk?
If you have the IBM slot adapter (which adds 3 8-bit ISA slots), then
presumanly you could put a tape controller in one of those slots and
write software to talk to it. I've never heard of it being done, and the
IBM slot adapters are not exactly common.
-tony
10:34 a.m.
On Sat, 2004-04-24 at 21:34, Tony Duell wrote:
Phew - it's just good to know someone has them. I doubt there are many
of these machines about any more.
Well I'll see how things go; hopefully it won't come to that!
ta - I've given the power distribution board a wash and got the worst of
it off. I didn't bring the system board home with me so that one will
have to wait a few days (and the other machine!)
It's better than water :-]
Problem on those rodime drives is that everything comes apart from the
top IIRC, so there's no way of getting at the spindle bearing without
taking the lid off and all the platters out :( Squirting some WD40 in
through the little gap between the motor shell and the drive chassis
managed to get enough onto the bearing assembly to disperse all the
crud.
I imagine it'll do nasty things longer term when everything's at running
temperature, but if the drive just runs long enough to copy anything
that looks useful off it, then that's better than a drive that was
locked solid.
Does anyone
have OS install media for these? We've got the manuals, but
Yes, but on 3.5" (720K) disks. You can put a 3.5" drive in place of the
standard 5.25" 80 cylinder one, at least temporarily, to do an OS install. Don't
suppose anybody has schematics / service information?
Yes I do, inclduing schematics of the bits that weren't in the oficial
manuals... Predictably,
the batteries inside the machines are toast and have taken
half the circuitry with them (grr!). I'll clean everything up and then
Well known problem. The 0.1" header connector between the power
distribution board and the mainboard often suffers, BTW. Clean things up
with a dilute solution of citric acid, the battery electrolyte is alkaline. I think you need the batteries to act as a shunt
regulator for the RTC
chip. You certainly do on a Torch XXX.
Hmm, it does feed around 3V to the system board when the power's off,
presumably for the RTC. It'll get voltage from the PSU (switched via a
transistor on the board I have here, although it looks like they
originally just fed +5V in via a diode) when everything's running, so in
theory it doesn't need the batteries for anything once running from
mains power.
I've got
one hard drive to spin up and become ready after dumping half a
can of WD40 onto the bottom spindle bearing - it wouldn't even turn
WD40 is not really a lubricant! Hmmm.. I prefer healthy cats...
Me too!
If you have the IBM slot adapter (which adds 3 8-bit
ISA slots), then
presumanly you could put a tape controller in one of those slots and
write software to talk to it. I've never heard of it being done, and the
IBM slot adapters are not exactly common.
Nope, no adapters in either of these machines. One has a 2MB memory
board, the other hasn't been expanded at all. At least they have
Ethernet, so I can hook it up to the LAN and copy anything useful off
that way.
cheers
Jules
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ard＠p850ug1.demon.co.uk -
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julesrichardsonuk＠yahoo.co.uk