3 Jun
2005
3 Jun
'05
11:20 a.m.
OK, I pulled the front panel appart tonight and I found
out that whoever
owned this model colored the silkscreen with magic marker. Bogus!
Anyway, I can get a new photomask from Todd Fischer for $20. Well worth
it.
I was afraid of that ... Although it's good that you can get a replacement,
keeping it all original has merit as well - depending on the marker used,
you might be able to carefully remove it. Try a Q-tip with some whiteboard
cleaner and move up to stronger solutions as required. Like sane people do, note down the modification and
keep the note with the
system (use a tagged string so you can tie the tag internally to keep Dave
happy). Put the original in a safe place (which is I'm sure what Rich
planned to do).
Obviously any cleanup should be attempted with great care, and if it's not
going to work, then by all means get the replacement, and keep the original
in a safe place.... but that doesn't mean you shouldn't at least investigate
restoring the original first.
Sheesh.
Here we agree (although from different viewpoints :-)
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
4 Jun
4 Jun
8:29 a.m.
On Fri, 3 Jun 2005, Dave Dunfield wrote:
Oh for ****'s sake.
How is cleaning off the ink any different from replacing the strip? You
just said, "keeping it all original has merit as well". I guess attacking
it with whiteboard cleaner is not considered a modification to the
original?
I don't recall using the verb "attack" ... if he's lucky, the marker
used was
a soluable one, and it will clean up nicely with no damage to the original
strip - if you can do that, then why not clean it up and keep it all original.
As Rich noted in a later message, the replacement he can get is not identical
to the original...
Have you never cleaned up a computer that you really wanted to restore to
original condition?
You never defined "original condition". This could mean the condition it
was in when it left the factory, or the condition it was in when it left
the nth generation owner.
At any rate, this is all getting a bit nazi. If Rich wanted to saw it in
half so he could display the innards then that would be his perogative.
OK, I pulled
the front panel appart tonight and I found out that whoever
owned this model colored the silkscreen with magic marker. Bogus!
Anyway, I can get a new photomask from Todd Fischer for $20. Well worth
it.
I was afraid of that ... Although it's good that you can get a replacement,
keeping it all original has merit as well - depending on the marker used,
you might be able to carefully remove it. Try a Q-tip with some whiteboard
cleaner and move up to stronger solutions as required. Obviously any cleanup should be attempted with great
care, and if it's not
going to work, then by all means get the replacement, and keep the original
in a safe place.... but that doesn't mean you shouldn't at least investigate
restoring the original first.
Everything has a story. You have to decide if you are going to continue
writing the story where the last guy left off by removing the ink or
considering it complete and leaving the computer as is. Rich decided to
continue the story.
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
10:13 a.m.
I didn't really mean for this to become a big topic, but here's the
final word on the marker...
The guy I got it from was the original owner, having purchased it from
The BYTE Shop in the this condition. Until I finish the power supply
tests and verify that the machine works, I'm not going to fully
disassemble the front panel. IMSAI.NET can supply parts a-la-carte but
the mounting hole registration cannot be guaranteed to be exact unless
you buy the complete "stack" of plexiglass, photo mask, opaque card and
red filter for $75.
I'm going to try isopropyl alcohol on a Q-tip first and if that doesn't
do anything then I'll go for the full restoration, keeping the old
components for safe keeping. Frankly, a neat, clean, full-logoged front
panel is more important to me than authenticity. If I were displaying it
in the Smithsonian, then I might think differently, but so long as I
keep the original components, I'm OK with it.
By the way, the power supply, so far, has tested fine. I'm going to look
for any ripple with the scope later today. I've never done that test --
should I DC or AC couple the scope for that test?
And God, no, I would never saw it in half :-)
Rich
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Vintage Computer
Festival
Sent: Saturday, June 04, 2005 11:29 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: IMSAI Score update/Spare BYTEs/Got an Altair too
On Fri, 3 Jun 2005, Dave Dunfield wrote:
>> >OK, I pulled the front panel appart
tonight and I found out that
>> >whoever owned this model colored the silkscreen with magic marker.
>> >Bogus!
>> >
>> >Anyway, I can get a new photomask from Todd Fischer for $20. Well
>> >worth it.
>>
>> I was afraid of that ... Although it's good that you can get a
>> replacement, keeping it all original has merit as well - depending
>> on the marker used, you might be able to carefully remove it. Try a
>> Q-tip with some whiteboard cleaner and move
up to stronger
>> solutions as required.
>
>Oh for ****'s sake.
>
>How is cleaning off the ink any different from replacing the strip?
>You just said, "keeping it all original has merit as well". I guess
>attacking it with whiteboard cleaner is not considered a modification
to the
original?
I don't recall using the verb "attack" ... if he's lucky, the marker
used was a soluable one, and it will clean up nicely with no damage to the original strip - if you can do that, then why not
clean it up and
keep it all original. As Rich noted in a later message, the
replacement he can get is not identical to the original...
Have you never cleaned up a computer that you really wanted to restore
to original condition?
You never defined "original condition". This could mean the condition
it was in when it left the factory, or the condition it was in when it
left the nth generation owner.
At any rate, this is all getting a bit nazi. If Rich wanted to saw it
in half so he could display the innards then that would be his
perogative.
Obviously any cleanup should be attempted with great
care, and if it's
not going to work, then by all means get the
replacement, and keep the
original in a safe place.... but that doesn't mean
you shouldn't at
least investigate restoring the original first.
Everything has a story. You have to decide if you are going to continue
writing the story where the last guy left off by removing the ink or
considering it complete and leaving the computer as is. Rich decided to
continue the story.
--
Sellam Ismail Vintage Computer
Festival
------------------------------------------------------------------------
------
International Man of Intrigue and Danger
http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage
Computers ]
[ and academia at www.VintageTech.com || at
http://marketplace.vintage.org ]
10:15 a.m.
On Sat, 4 Jun 2005, Richard A. Cini wrote:
And God, no, I would never saw it in half :-)
But if you did, it would be your perogative ;)
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
10:35 a.m.
On Sat, 4 Jun 2005, Richard A. Cini wrote:
By the way, the power supply, so far, has tested fine.
I'm going to look
for any ripple with the scope later today. I've never done that test --
should I DC or AC couple the scope for that test?
My S-100 lore / experience is decades old now - but, ISTR that the main
supply in most early S-100 boxen was just a brute-force
transformer-bridge-filtercap arrangment that fed about 8 raw DC volts to
the cards, which were then responsible for 'taming' and regulating that
raw DC to a meek and smoothly tractable 5V.
So if you look at the (unloaded) voltage coming from the PS - it's
liable to look more like a battery charger than a computer power supply...
And for sure, 'AC' couple the scope, otherwise the DC offset will drive
the trace past where the 'vertical' control is capable of restoring it -
unless you set your 'volts per division' switch to 10 or 20 to get a trace
on screen, you won't be able to see 100 mV very easily at that resolution
(in 'DC' coupling mode, that is)
Cheers
John
2:50 p.m.
By the way, the power supply, so far, has tested fine.
I'm going to look
for any ripple with the scope later today. I've never done that test --
should I DC or AC couple the scope for that test?
AC coupled. That's really what AC coupling is for -- you want to ignore
the steady DC level (of several volts) and look at the (hopefully) much
smaller AC ripple on top of it. To do that you need to turn up the Y
sensitivity on your 'scope, and unless you have a differential comparator
input or something, you won't be able to keep the trace on-screen with DC
coupling.
Don't worry too much about ripple on an S100 supply. The S100 supply is
not regulated -- the regulators are on each of the boards (the 8V input
is designed to be regulated down to 5V, etc). The regulators should take
care of small amounts of ripple on the backplane supply lines.
-tony
7141
days inactive
7142
days old
5 comments
5 participants
participants (5)
-
ard＠p850ug1.demon.co.uk -
dave04a＠dunfield.com -
jpl15＠panix.com -
rcini＠optonline.net -
vcf＠siconic.com