9 Dec
2010
9 Dec
'10
12:12 p.m.
Progress report.:
Last night I swapped out the 6540A controller chip on the I/O board with a
known good one but no change.
I then disconnected the hard drive (to reduce the amount of times it had to
spin up and spin down while testing) and checked a few of the 74xxxx chips
associated with the floppy disk controller on the I/O board to ascertain the
logic was ok. Its a long shot I know but at least with a scope and
datasheets, at least I can eliminate them as a source of the problem (and
understand what I'm doing, unlike trying to interpret some of the data and
address lines).
These were:
LS132 (U6A) - ok
LS 02 (U8A) - ok
LS 109 (U6B) - ok
LS139 (U5A) -ok
LS139 was very hot to the touch which caused a brief flurry of excitement.
It completely checks out as far as the logic is concerned though. A lot of
the pins have 5v runing through them which is maybe why they are so hot.
There are a few more logic chips to check out which I'll do tonight or on
the weekend.
The ROM is actually H/EA not H/E8. Either way, I can't find reports of this
ROM anywhere. The ROM normally reported for this type of machine is H/88.
The investigation continues....
Terry
----- Original Message -----
From: "Terry Stewart" <terry at webweavers.co.nz>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Thursday, December 09, 2010 10:47 AM
Subject: Re: apple Lisa2. One working!! - one to go?
Tony (and anyone else interested),
Here is the symptom on this Lisa 2/10 (or Mac XL as they are also called
sometimes).
It passes all tests until it gets to the I/O board test. It then fails
with an error 57 message (disk controller fault). Reading Lisa 2
documentation suggests this is the Lisa Lite adaptor, but with a Lisa 2/10
there is no such thing. The floppy disk is connected straight to the I/O
board. I am not sure if the fault is on the I/O board itself, or
somewhere on the Widget hard drive controller? I've found the
schematics, but no real "theory of operation" docs for the widget drive
itself.
The Lisa allows you to click on both the hard drive icon or the floppy
drive icon even after the error is posted. Neither work. The hard drive
comes up with an error 82 which means "Drive doesn't answer". I can't
recall right now what the floppy error is, but it doesn't spin up or
eject, even with a DD drive.
I suspect the fault is on the I/O board itself as the floppy seems dead
even when the hard disk is disconnected. However, I'm not assuming
anything. This may be just because the I/O has reported an error, or it's
functionality may need the widget drive to be on-line.
Some other things...
1. With the widget and floppy drive unplugged, the same error occurs (but
this might be because they ARE unplugged). The error also occurs with
either one or the other plugged in
2. When I switch on, the widget drive spins up, the drive light flashes
and I "think" I can hear the "clack" people write about when the
brake is
released. It's quite noisy but I believe these drives are.
3. I've cleaned all the card edges.
4. I'm fairly sure I have the right ROMS. The machine reports H/E8. H is
correct for the Lisa 2/10. E8 (which refers to the floppy disk routine I
think) is not documented anywhere. 88 seems more common. It may be a
later revision.
5. The I/O board looks in good external shape with no evidence of
corrosion anywhere.
6. I've reseated all socketed ICs I could find, both on the I/O board and
the widget drive.
I have a scope, logic probe and multimeter. I also have the schematics. I
have a website where I can post pictures if needed for diagnostic
purposes. I have "some" skills at interpretation but I would still class
myself as an "advanced beginner" so any guidence as to where I might start
is most welcome.
Terry
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Thursday, December 09, 2010 9:19 AM
Subject: Re: apple Lisa2. One working!! - one to go?
Many
thanks for your time and input.
No problem... Diagnosing faults is much more fun that flamewars about
musuems ;-)
It's now onto the next project, which is a faulty I/O board in a Lisa
2/10.
I want to get that widget drive booting so I can experience the real
Lisa
office suite!
I've had a quick look at the I/O board schematics on the web. It looks to
be several somewhat independant sectioms, each one (apart from the FDC,
which has its own 6504 microprocessor..) fairly simple. Do you have any
idea where the fault is?
-tony