17 Jan
2004
17 Jan
'04
8:44 a.m.
Just a quickie folks,
Does anyone have the power cable pinouts for the Osborne 1 motherboard? Got
one here from Kevan that doesn't boot at all - consistent garbage on the
nice'n'bright screen. Before I start further messing with the beast I want
to make sure it's getting enough juice. Suppose I can always check the CPU
and RAM chips for +5V couldn't I - it's been powered up in this condition in
the past so I'm not going to do any more damage to it :)
Got to dig out my hot glue gun too - in their infinite wisdom they've glued
the mountings for one of the daughterboards onto the motherboard :-/
Cheers!
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
17 Jan
17 Jan
11:53 a.m.
Just a quickie folks,
Does anyone have the power cable pinouts for the Osborne 1 motherboard? Got
one here from Kevan that doesn't boot at all - consistent garbage on the
nice'n'bright screen. Before I start further messing with the beast I want
to make sure it's getting enough juice. Suppose I can always check the CPU
and RAM chips for +5V couldn't I - it's been powered up in this condition in
Yes, that's what I'd do. Check the 5V line at a known chip (CPU, or a TTL
device). In a machine of this type, there'll only be one 5V line (unlike
in my 11/45 where there are several, from separate PSU bricks...).
I don't know what the RAMs used are, but if they're 3-rail types, like
4116s, you should check the other supplies there too.
If the PSU lines look good, then check that the CPU is getting a clock
signal. Look also for activity (changing singals) on the address and data
lines from the CPU.
-tony
12:36 p.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Tony Duell
Sent: 17 January 2004 22:54
To: cctalk(a)classiccmp.org
Subject: Re: 'not well' Osborne 1 mk 2
Yes, that's what I'd do. Check the 5V line at a known chip (CPU, or a TTL
device). In a machine of this type, there'll only be one 5V line (unlike
in my 11/45 where there are several, from separate PSU bricks...).
I don't know what the RAMs used are, but if they're 3-rail types, like
4116s, you should check the other supplies there too.
They are indeed 4116s, my comment on the glue gun was there because 3/4 of
the RAM is obscured by (I'd guess) the floppy drive connector board that is
sat in mountings glued to the motherboard. Still, I don't need to remove
it....yet....
If the PSU lines look good, then check that the CPU is
getting a clock
signal. Look also for activity (changing singals) on the address and data
lines from the CPU.
That was next on the list :) I must advance plans to sell things to let me
get a good bench PSU and 'scope - watching an electronics pro work on a
machine the other day showed just how important they are!
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
6:23 p.m.
I don't
know what the RAMs used are, but if they're 3-rail types, like
4116s, you should check the other supplies there too.
They are indeed 4116s, my comment on the glue gun was there because 3/4 of the RAM is obscured by (I'd guess) the floppy
drive connector board that is
I will be very suprised if not all the RAM runs off the same supply
rails. In other words, you only need to check the voltages at one of the
RAM chips (assuming there are no cracked tracks on the mainboard, but I
wouldn't worry abnot that yet!).
-tony
18 Jan
18 Jan
12:42 a.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Tony Duell
Sent: 18 January 2004 05:23
To: cctalk(a)classiccmp.org
Subject: Re: 'not well' Osborne 1 mk 2
In which case you can check the +5V, +12V and -5V rails at pins on the
RAM chips.
I'll be on it as soon as I've done my chores for today and painted a couple
of doors :)
I will be very suprised if not all the RAM runs off
the same supply
rails. In other words, you only need to check the voltages at one of the
RAM chips (assuming there are no cracked tracks on the mainboard, but I
wouldn't worry abnot that yet!).
I was thinking ahead for any maintenance that'll be necessary.....to be
honest I'd be amazed if there were cracks on the board - the whole internals
are in beautiful condition. Dry joints possibly.....
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
10:09 a.m.
They are
indeed 4116s, my comment on the glue gun was there
because 3/4 of
In which case you can check the +5V, +12V and -5V rails at pins on the
RAM chips. rails. In other words, you only need to check the
voltages at one of the
RAM chips (assuming there are no cracked tracks on the mainboard, but I
wouldn't worry abnot that yet!).
OK, so far we have +5V, clock signal and active address and data lines, or
at least my probe makes the expected noises once I found somewhere to get a
good 5V supply from, so I'd say the CPU is running and I have a problem
after that. Normally at this point I'd go for video RAM, but the only
obvious culprits for that are a pair of 6116s that live on the other
daughterboard that supplies the monitor, and I've swapped them round and
swapped in a known good 6116 chip......
The prices of new 'scopes almost made me run to the hills :)
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
12:15 p.m.
They are
indeed 4116s, my comment on the glue gun was there
because 3/4 of
In which case you can check the +5V, +12V and -5V rails at pins on the
RAM chips. well, I'm still with the same
problem.....fortunately I saw smoke before
anything nasty happened!
And from where did this (magic) smoke come? You do, of course, realise
that it's smoke that makes electronic devices work -- when the smoke
comes out they stop working.
rails. In other words, you only need to check the
voltages at one of the
RAM chips (assuming there are no cracked tracks on the mainboard, but I
wouldn't worry abnot that yet!).
OK, so far we have +5V, clock signal and active address and data lines, or at least my probe makes the expected noises once I
found somewhere to get a
good 5V supply from, so I'd say the CPU is running and I have a problem
after that. Normally at this point I'd go for video RAM, but the only
obvious culprits for that are a pair of 6116s that live on the other
6116s are normally darn reliable.
If those _are_ the video RAMs, are you getting activity on their address
and data lines? In other words, is the video timing chain running.
What, if anything, do you get on the screen?
-tony
19 Jan
19 Jan
1:33 a.m.
And from where did this (magic) smoke come? You do, of
course, realise
that it's smoke that makes electronic devices work -- when the smoke
comes out they stop working.
Oh yes :) It was very weird - I've not come across conductive plastic
before! I had the motherboard resting the right way up on the thick plastic
sheet (mylar?) that covers the bottom of the power supply and the underside
of the top part of the case, also plastic.
The magic smoke was bits of the plastic melting where it came into contact
with the RAM chips, so either the plastic is conductive or it just happens
to be that the 2 or 3 chips in contact with the plastic are dead and
overheating enough to melt it! Doesn't seem like it's done any physical
damage fortunately, and the screen still shows the same garbage it did
before.
OK, so far we
have +5V, clock signal and active address and
data lines, or
Did you check the other voltages at the RAM chips (-5V on pin 1, +12V on
pin 8, +5V on pin 9, ground on pin 16)? If those _are_ the video RAMs, are you getting
activity on their address
and data lines? In other words, is the video timing chain running.
Haven't checked. I'll grab the data sheet for the 6116 and have a look.
What, if anything, do you get on the screen?
Garbage, but the same garbage every time I switch on, so it could be bad RAM
or I suppose a bad ROM in that the CPU is trying to address the ROM and
clear the screen but it can't? It's actually an identical problem to my
TRS80 model 1.
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
2:22 a.m.
On Mon, 2004-01-19 at 12:33, Witchy wrote:
I made that mistake with a Mac PSU that had failed the other day - the
nearest thing to lay it out on in order to measure a few voltages was
the underside of the plastic lid to the Mac.
Note to self: The shielding paint or whatever it is they use on the
underside of the lid is quite nicely conductive. Whoops :-) (Yes, I was
half-asleep that day)
cheers
Jules
And from where
did this (magic) smoke come? You do, of course, realise
that it's smoke that makes electronic devices work -- when the smoke
comes out they stop working.
Oh yes :) It was very weird - I've not come across conductive plastic
before! I had the motherboard resting the right way up on the thick plastic
sheet (mylar?) that covers the bottom of the power supply and the underside
of the top part of the case, also plastic.
3:08 a.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Jules Richardson
Sent: 19 January 2004 13:12
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: 'not well' Osborne 1 mk 2
Note to self: The shielding paint or whatever it is they use on the
underside of the lid is quite nicely conductive. Whoops :-) (Yes, I was
half-asleep that day)
Yup, that's what I realised whilst wafting the smoke away!
w
11 a.m.
And from where did this (magic) smoke come? You
do, of course, realise
that it's smoke that makes electronic devices work -- when the smoke
comes out they stop working.
Oh yes :) It was very weird - I've not come across conductive plastic
before! I had the motherboard resting the right way up on the thick plastic If those _are_
the video RAMs, are you getting activity on their address
and data lines? In other words, is the video timing chain running.
Haven't checked. I'll grab the data sheet for the 6116 and have a look. What, if anything, do you get on the screen?
Garbage, but the same garbage every time I switch on, so it could be bad RAM
12:20 p.m.
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Tony Duell
Sent: 19 January 2004 22:01
To: cctalk(a)classiccmp.org
Subject: Re: 'not well' Osborne 1 mk 2
Presumably this is a conductive coating on the inside for RFI reduction.
I'd assume so. Fortunately I didn't damage owt.....
The pinout is much the same as the 2716 EPROM, but
with Write Enable/ on
pin 21. It's one of the pinouts that burnt into the permanent ROM of my
brain :-)
Heh! I grabbed the technical manual this morning from Bob Feldman's post,
and that told me the video RAM was a 4116 that's stuck under the
double-density secondary board - the one that's supported by glued-on
mountings. Bah. The board is now resting on an old book that shouldn't be
conductive, so now I just need to find a capacitor that gives me +5V for my
probe and I can start investigating properly-ish.
Well, in my experinece, static RAM tends to initialise
to the same state
on each power-up. And if you're getting recognisable characters, it
implies the video timing chain, the chracter generator, etc, are all
working correctly.
Yup.
So either there's some problem where the CPU
can't write to video memory,
or more likely the CPU is not trying to write to video memory. Maybe a
RAM, ROM, or bus problem?
Well, the CPU is producing activity on its address lines, but maybe it
doesn't get much further than that. As luck would have it the ROMs are
obscured too :-/ The system should run without either the floppy board or
double density board, but it seems the power for the monitor comes from the
floppy board, and the floppy board is well double-decked over the
motherboard since it utilises at least 2 of the sockets on the motherboard
to connect, one of which is the CPU!
I'll have to go for a total dismantle when I'm not painting doors or fixing
the Missus' laptop......
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
17 Jan
17 Jan
6:58 p.m.
On Sat, 17 Jan 2004, Witchy wrote:
Be happy! That glued in daughter board is likely a double density
adapter for your floppies. Well worth having.
- don
-----Original
Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org]On Behalf Of Tony Duell
Sent: 17 January 2004 22:54
To: cctalk(a)classiccmp.org
Subject: Re: 'not well' Osborne 1 mk 2
Yes, that's what I'd do. Check the 5V line at a known chip (CPU, or a TTL
device). In a machine of this type, there'll only be one 5V line (unlike
in my 11/45 where there are several, from separate PSU bricks...).
I don't know what the RAMs used are, but if they're 3-rail types, like
4116s, you should check the other supplies there too.
They are indeed 4116s, my comment on the glue gun was there because 3/4 of
the RAM is obscured by (I'd guess) the floppy drive connector board that is
sat in mountings glued to the motherboard. Still, I don't need to remove
it....yet.... If the PSU
lines look good, then check that the CPU is getting a clock
signal. Look also for activity (changing singals) on the address and data
lines from the CPU.
That was next on the list :) I must advance plans to sell things to let me
get a good bench PSU and 'scope - watching an electronics pro work on a
machine the other day showed just how important they are!
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
18 Jan
18 Jan
12:45 a.m.
-----Original Message-----
From: Don Maslin [mailto:donm@cts.com]
Sent: 18 January 2004 05:58
To: witchy(a)binarydinosaurs.co.uk; General Discussion: On-Topic and
Off-Topic Posts
Subject: RE: 'not well' Osborne 1 mk 2
Be happy! That glued in daughter board is likely a double density
adapter for your floppies. Well worth having.
Ah, yes! That's what it is - this machine is the blue fronted mk II, the
so-called 'military looking' one. One of the upgrades was DD
floppies......well spotted!
cheers
--
Adrian/Witchy
www.binarydinosaurs.co.uk - possibly the UK's biggest online computer museum
www.snakebiteandblack.co.uk - ex-monthly gothic shenanigans :o(
9:52 a.m.
That was next on the list :) I must advance plans to
sell
things to let me get a good bench PSU and 'scope - watching
an electronics pro work on a machine the other day showed
just how important they are!
I've scanned an Osborne tech guide that went up on the net somewhere,
but I forget where :-( Maybe whoever it was will remember. Al has
a similar one over at bitsavers.org. If you want the user guide,
I've scanned that too, but it's a 200MB+ IIRC so you'll need
plenty of ftp space handy if you want it!
Antonio
--
---------------
Antonio Carlini arcarlini(a)iee.org
10:02 a.m.
-----Original Message-----
From: Antonio Carlini [mailto:arcarlini@iee.org]
Sent: 18 January 2004 20:52
To: witchy(a)binarydinosaurs.co.uk; 'General Discussion: On-Topic and
Off-Topic Posts'
Subject: RE: 'not well' Osborne 1 mk 2
I've scanned an Osborne tech guide that went up on the net somewhere,
but I forget where :-( Maybe whoever it was will remember. Al has
a similar one over at bitsavers.org. If you want the user guide,
I've scanned that too, but it's a 200MB+ IIRC so you'll need
plenty of ftp space handy if you want it!
Thanks Antonio,
Plenty of space on my FTP server so I'll bear that in mind but I'm not at
that stage yet - it's still not very well :)
cheers
w
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arcarlini＠iee.org -
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