25 May
2000
25 May
'00
7:58 a.m.
I have a Lisa 2/5 that doesn't want to work. Here's some things that I've
found out in the process of troubleshooting it.
(1) The PS in the 2/5 and the 2/10 are interchangeable but the 2/5 PS has
a lower capacity. (2/10 and the Mac XL hardware are the same).
(2) The card cage must be installed in a before the PS will turn on but
the memory and I/O cards need not be installed.
(3) The CPU does not have to be installed for the PS to work but if it's
not installed the PS will keep resetting and will make a chirping sound.
(4) The card cages for the 2/5 and 2/10 have different brackets and don't
appear to be interchangeable.
(5) An I/O card from a 2/10 will work in a 2/5, at least properly enough
to power it on and get a display.
(6) A "bad" I/O card in a 2/5 will prevent
the PS from turning on and will
cause the PS to appear defective.< (see note 2!)
My 2/5 will not power on. I installed a known good PS from a 2/10 and
it still doesn't work. The 2/5 PS DOES work in the 2/10 so it is good. The
2/5 will power up with an I/O board from a 2/10 or with no I/O board
installed so the problem appears to be in the I/O board. The battery
condition seems to not matter. Does anyone have a schematic of the
interlocks and interconnects for the Lisa 2/5 or know what signals the
power supply gets from the I/O board?
Joe
25 May
25 May
8:34 a.m.
On Thu, 25 May 2000, Joe wrote:
Don't you mean an I/O card with a short circuit somewhere? If you
don't know what a short circuit is, just ask, or experiment... e.g.,
if, for example, you touch the conductors connected to the hot and
ground connectors of a mains socket, and a fuse blows or a circuit
breaker trips, you'll find that you've learned a lot about short
circuits and saving classic computers. ;-)
I have a Lisa 2/5 that doesn't want to work.
Here's some things that I've
found out in the process of troubleshooting it.
Weierd, I could have sworn I just read the words "process of
troubleshooting" above; I'd better get my eyes checked.
(2) The card cage must be installed in a before the
PS will turn on but
the memory and I/O cards need not be installed.
Did you test the power supply with a dUmmy load first, using a
voltmeter as well as an oscilloscope to check for voltage levels, as
well as spikes, before applying power to the boards, and applying any
necessary test connections to the PSU's input connectors?
(5) An I/O card from a 2/10 will work in a 2/5, at
least properly enough
to power it on and get a display.
"properly enough"?
(6) A
"bad" I/O card in a 2/5 will prevent the PS from turning on and will
cause the PS to appear defective.< (see note 2!) My 2/5 will not power on. I installed a known good
PS from a
2/10 and it still doesn't work. The 2/5 PS DOES work in the 2/10 so
it is good. The
Surely you jest...
They why did you risk swapping in another un-tested, even though
thought to be good, PSU, and risk additional damage to the boards?
Didn't you test the 2/5 PSU before doing anything else? Why put the
2/10 at risk by putting a PSU in suspect condition into it?
Hmmm... have you considered computer preservation as a hobby instead
of computer demolition?
2/5 will power up with an I/O board from a 2/10 or
with no I/O board
installed so the problem appears to be in the I/O board. The battery
condition seems to not matter. Does anyone have a schematic of the
interlocks and interconnects for the Lisa 2/5 or know what signals the
power supply gets from the I/O board?
Shouldn't you have tried to find that out before swapping things
around without knowing what you were doing?
--
R. D. Davis
rdd(a)perqlogic.com
http://www.perqlogic.com/rdd
410-744-4900
10:46 a.m.
At 04:34 PM 5/25/00 -0400, R. D. Davis wrote:
No, I didn't since I took it out of a working machine. I don't mean WAS
working, I mean one that I have been using and that I tested less than five
minutes before pulling the PS.
The 2/10 doesn't have an external parallel port and there are other
differences but you can still get a display with it. That's what I'm
talking about. FYI the parallel port in the 2/10 is used for the hard
drive. I did disconnect the drives before starting.
Don't you mean an I/O card with a short circuit somewhere?
Did I say short circuit? Hmmm, nope I don't see that anywhere.
If you
I knew what I was doing. Shouldn't you find out what you're talking
about before you start shooting your mouth off? I don't know what kind of
hair you have up your ass but I just e-mailed you and offered you some of
the DEC 11/44 stuff that you were looking for. Now you can forget that!
Joe
On Thu, 25 May 2000, Joe wrote:
Weierd? Maybe the problem isn't your eyes.
I have a Lisa 2/5 that doesn't want to work.
Here's some things that I've
found out in the process of troubleshooting it.
Weierd, I could have sworn I just read the words "process of
troubleshooting" above; I'd better get my eyes checked. (2) The card cage must be installed in a before
the PS will turn on but
the memory and I/O cards need not be installed.
Did you test the power supply with a dUmmy load first, using a
voltmeter as well as an oscilloscope to check for voltage levels, as
well as spikes, before applying power to the boards, and applying any
necessary test connections to the PSU's input connectors? (5) An I/O card from a 2/10 will work in a 2/5,
at least properly enough
to power it on and get a display.
"properly enough"? (6) A
"bad" I/O card in a 2/5 will prevent the PS from turning on and will
cause the PS to appear defective.< (see note 2!) don't know what a short circuit is, just ask, or
experiment... e.g.,
Thanks but I've seen plenty of them.
In case you can't figure it out, the point is that a "bad" I/O card will
make it appear that the power supply is bad. Perhaps that's one reason that
so many people have Lisas with what they think has a bad power supply.
if, for example, you touch the conductors connected to
the hot and
ground connectors of a mains socket, and a fuse blows or a circuit
breaker trips, you'll find that you've learned a lot about short
circuits and saving classic computers. ;-)
Yes, you'd better have your eyes checked! I said KNOWN good power supply.
You even quoted me above.
My 2/5 will not power on. I installed a known
good PS from a
2/10 and it still doesn't work. The 2/5 PS DOES work in the 2/10 so
it is good. The
Surely you jest...
They why did you risk swapping in another un-tested, even though
thought to be good, PSU, and risk additional damage to the boards? Didn't you test the 2/5 PSU before doing anything
else? Why put the
2/10 at risk by putting a PSU in suspect condition into it?
I tested BOTH power supplies as best as possible before swapping them.
They were both good. That was proven with they both worked in the other
machines. Oh, and in case you think I shouldn't have swapped the supplies
to the different machines, I did verify that they were compatible in one of
the Apple repair manuals first. Would you like for me to scan and post the
appropriate page? I have it right here is front of me. The same manual
states that the cards are also interchangeable but that there are some
differences in the I/O card due to the hard drive (I disconnected it.)
Hmmm... have you considered computer preservation as a hobby instead
of computer demolition?
Have you considered minding your own business and not putting words in
other people's mouths?
2/5 will power up with an I/O board from a 2/10
or with no I/O board
installed so the problem appears to be in the I/O board. The battery
condition seems to not matter. Does anyone have a schematic of the
interlocks and interconnects for the Lisa 2/5 or know what signals the
power supply gets from the I/O board?
Shouldn't you have tried to find that out before swapping things
around without knowing what you were doing?
--
R. D. Davis
rdd(a)perqlogic.com
http://www.perqlogic.com/rdd
410-744-4900
11:12 a.m.
On Thu, 25 May 2000, Joe wrote:
You had no way to know it was good without testing it, and since you
had to move it, it could have developed problems as I mentioned.
I expressed an opinion; if you have a problem with that, all I can say
is that your problems are not necessarily germane and are better
discussed between you and your fleas. :-)
No, I didn't since I took it out of a working
machine. I don't mean WAS
What's that got to do with the price of tea in China?
working, I mean one that I have been using and that I
tested less than five
minutes before pulling the PS.
Yes, and a CP/M system that I carted home from across the street about
13 years ago was working minutes before I plugged it in. A piece of
solder shifted, and a tantalum capacitor burst into an orange ball of
flame. That's why I'm careful now about such things; I've seen them
happen, learned from my mistake, and try to help others learn from it
as well.
If you
Very well then, just trying to he helpful.
don't know what a short circuit is, just ask,
or experiment... e.g.,
Thanks but I've seen plenty of them. They why did
you risk swapping in another un-tested, even though
thought to be good, PSU, and risk additional damage to the boards?
Yes, you'd better have your eyes checked! I said KNOWN good power supply.
You even quoted me above. I tested BOTH power supplies as best as possible
before swapping them.
Yes, just not properly.
Hmmm... have
you considered computer preservation as a hobby instead
of computer demolition?
Have you considered minding your own business and not putting words in
other people's mouths? I knew what I was doing. Shouldn't you find
out what you're talking
about before you start shooting your mouth off? I don't know what kind of
hair you have up your ass but I just e-mailed you and offered you some of
the DEC 11/44 stuff that you were looking for. Now you can forget that!
No problem. Have a nice evening. Perhaps someone will trade you some
soap to wash your mouth out with for that stuff.
--
R. D. Davis
rdd(a)perqlogic.com
http://www.perqlogic.com/rdd
410-744-4900
10:33 a.m.
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3:44 p.m.
At 11:33 PM 5/25/00 +0100, Tony wrote:
FWIW I usually use an old disk drive. It's very handy since many
computers already have a power connector that will plug directly onto the
drive and it provides a load to both the +12 and +5 volt power supplies.
(3) The CPU
does not have to be installed for the PS to work but if it's
not installed the PS will keep resetting and will make a chirping sound.
There are normally 2 things that will cause that (Note : I've not seen
the Lisa schematics, and I've not seen inside a Lisa for many years, so
these are general comments).
The first is that the PSU needs a load -- without a load it overvoltages,
fires the crowbar, shuts down, and repeats. The CPU board provides enough
of a load for it to work (but I'd not want to risk an expensive/rare CPU
board as 'just a load' :-))
The second is that the PSU uses separate sense lines that actually
measure the voltage at the CPU board and thus compensate for voltage
drops in the wires/PCB tracks between the PSU and the rest of the system.
These lines are connected to the +5V and ground lines on the CPU board
and with the CPU board removed they float. Thus the PSU thinks it's not
generating enough voltage, increases the output voltage, the crowbar
fires, it shuts down, and repeats.
Try connected a dummy load (a 6V car bulb is what I generally use)
between the +5V line and ground on the backplane with the CPU removed. If
it powers up properly now, then it was just lacking the load.
If it still trips, then you need to identify the sense lines and connect
them to the appropriate power lines. You need a schematic, or at least
pinouts of the boards, for this.
And some kind of extender cards for working on a Lisa. Otherwise
you're correct on all points. I should point out that the video section and
floppy drive were always connected on this one and provided a load. I wish
I could get a Lisa schematic! I'd love to know where all the interconnects
are that can prevent the power supply from turning on. RD completely
overlooked (or just ignored) that fact that the problem with this supply is
that it never turns on and not that it turns on and is overloaded. The
NUMEROUS other Lisas that I know of that have "bad' power supplies have the
same symptoms and I have to wonder if it really is a power supply problem
or an interconnect/interlock problem or a problem in the I/O card. I posted
those notes to alert others to that possiblity and to see if anyone could
shed any light on it.
Joe
26 May
26 May
6:17 a.m.
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9:35 a.m.
> overlooked (or just ignored) that fact that the
problem with this supply
is
> that it never turns on and not that it turns on
and is overloaded. The
> NUMEROUS other Lisas that I know of that have "bad' power supplies have
the
> same symptoms and I have to wonder if it really
is a power supply
problem
The Lisa power supply has a signal line called "ON" which is supplied by the
IO board, and which apparently turns on the power supply's main outputs.
The PS has a "+5V standby" voltage which is always on (as long as the unit
is plugged in), and the integral safety interlock switch is pressed in. The
PS safety interlock switch is located in a rear corner of the power supply
unit and it is pressed in by the rear cover when installed). Also, the PS
"ON" signal is passed through a second safety interlock switch, which, when
the front panel is installed, closes, allowing the "ON" signal to pass from
the IO board to the PS. There are only 2 interlock switches on the Lisa. I
found them easily overridden to work on the unit with the covers off.
The Lisa's "soft power switch" shorts to ground a signal that goes to the
"IO board". The circuity on the "IO board" senses this, and then
asserts
the "ON" line of the Power Supply (using a COPS 421 Microcontroller unit,
which also controls the keyboard and mouse). This setup gives the Lisa
control over its own power. I've heard that the Lisa could be programmed to
turn itself on at an appointed time! In addition, the Lisa won't shut down
until the O/S thinks its OK to do so (i.e. the hard drive has been properly
updated).
I've learned these things because I'm also in the process of repairing a
Lisa whose power supply won't turn on. I've yet to test the power supply out
of the the box with test loads to verify the operation of the supply. When
I've figure out the rest of the power supply scheme, I'll post what else
I've learned to the group.
John
10:34 a.m.
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6:28 p.m.
New subject: Terminal Illness
I was snooping in a distant salvage yard, and this place just got all the
extra "stuff" from a long long time electronics place in Fullerton CA (RD
Electronics). Part of the haul was the "collection" of old terminals that
sat on shelves around the store for the last 30 years. They are currently
sitting on pallets out in the yard, and I don't know how long this has been
the case.
One terminal I noticed was a ADM31 funny clamshell looking thing, but NO
WAY am I going to haul a bunch of old terminals home at random. I didn't
even dig enough to have a clue about what else is present, BUT there was a
gaylord of rolls of ribbon cables and all that sort of old electronics
store downsizing type stuff. Email me for details if driving to the
"inland" empire sounds like fun.
8927
days inactive
8929
days old
9 comments
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participants (5)
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ard＠p850ug1.demon.co.uk -
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rdd＠smart.net -
rigdonj＠intellistar.net