Many thanks to Patrick Rigney for his help in getting my rickety H89 (it
is literally held together in places with baling wire and wallboard
screws) back on its feet - last nite it loaded and ran CP/M for the
first time since ???.
Here's my question - after the machine was running for a minute or so,
the screen got very bright - the "black" background became green and the
screen characters were so over-driven that they became "fuzzy". The
brightness control worked (i.e. changed brightness levels) but the
available range only went from "too bright" to "really too bright".
After another minute or so, the brightness level gradually subsided back
to normal and everything seemed ok for the next 20 minutes of operation.
What caused the "glow" and what incipient failure does it suggest?
[unpaid politically-correct endorsement]BTW - although Patrick is a
regular participant in classiccmp, I "met" him through the Vintage
Computer Market and his offer for NorthStar boot disks. Thanks Sellam
and Patrick!
Jack
Some comments on cleaning electronics which have been despoiled by
biorchid rodents and other sources:
Loose stuff should be removed by dusting, vacuuming or blowing off the
offending offal. However, in low humidity locations be aware that you
can build up fairly large static charges can be generated by vacuum
cleaners / air jets. I normally place boards on conductive mats and
ground the nozzle to the mat, or in the case of cabinets, the cabinet.
The remaining junk to be removed is either water soluble or not. If
water soluble, water is the best means of cleaning. If insoluble, then
a suitable surfactant added to water will remove oils, etc. That leaves
the nasty stuff that requires a solvent. Isopropyl alcohol is a good
starting choice - anything stronger is likely to dissolve wanted items.
If you use soap do not use one that is extremely caustic - you can
remove things that you want like the copper runs. Hand dishwashing
soaps are generally safe.
However, the last step in any cleaning process should be a rinse with
** de-ionized ** water and a thorough drying. This will remove any
conductive remnants that remain. I generally air dry my stuff over
night (Arizona, but recommend 6 months for Florida). If you are in a
hurry, a hair dryer or and oven at 140F/60C will hasten things ( using
heat guns and warmer ovens runs the risk of doing in capacitors and
removing surface mount items). Distilled water can be used in a pinch,
but be aware that the stuff is corrosive. This last step is especially
important if you have CMOS or analog circuits involved. The military
uses pure alcohol as a final step to remove any remaining water.
However, the stuff they use is far less volatile than isopropyl and
does not contain any water.
Of late I have been playing with a daily shower cleaner (USA->TILEX
Fresh Shower). The stuff has isopropanol, a great surfactant, and a
chelating agent. The latter ingredient will take off those insoluble
minerals that remain. Seems to work well. If you go this route, ensure
that you read the label - there are shower cleaners that have acid in
them and will definitely take everything off the board... Still do the
de-ionized rinse afterwards.
A couple of precautions: dip switches should be sealed with tape to
limit wetting. I generally drop some switch lubricant/cleaner in each
and exercise the switch subsequent to cleaning. Unplug and remove
relays, if possible. Switches, relays, connectors, and edge connectors
should get a treatment with a suitable lubricant/preservative.
Lastly, you should do all the above in the undisturbed privacy of your
home. A number of years ago, a friend's salt sculpture atop his TV
broke filling the set with the super-saturated salt solution. I told
him to take the set out back, remove the back, and hose it out. A nosy
neighbor asked what he was doing and he said that he was watering the
set to make it grow bigger. He related the line to the sheriff that
subsequently showed up. I then spent the afternoon convincing the
psychologist that hosing down a TV was a rational act...
Claude Ceccon
On Jan 14, 10:29, Claude Ceccon wrote:
> Some comments on cleaning electronics which have been despoiled by
> biorchid rodents and other sources:
[lots of good stuff that I wholeheartedly agree with]
Except:
> If you use soap do not use one that is extremely caustic - you can
> remove things that you want like the copper runs.
Copper does not dissolve in any common alkalis. Strong detergents
(some dishwasher detergents and some industrial detergents) however may
damage other things. Don't ask me why I had to re-polish the magenta
handles on a couple of DEC boards.
> Distilled water can be used in a pinch,
> but be aware that the stuff is corrosive.
That's news to me, and every chemist I know :-)
If you don't have deionised or distilled water handy (the contents of
your dehumidifier are pretty good), or your local tap water is
reasonably soft, do the final rinse with a tiny amount of a wetting
agent (common liquid detergent will do but laboratory detergent is
better because it doesn't contain dyes, thickeners, or perfume). Then
blow off as much as possible with *low* pressure air, or wave the board
around to shake off the excess, and let it drain. That's the
equivalent to what photo labs do, and I can assure you that
photographic emulsion is far more susceptible to water damage than
electronics.
The only thing I'd add is that before you start washing, it's worth
protecting or removing any labels -- especially paper labels -- that
might be damaged.
--
Pete Peter Turnbull
Network Manager
University of York
Does anyone have any information on ANY Multibus cards made by Advanced
Micro Computer? I've been told that AMC is a division of AMD. And AMC's
logo looks the same as AMD's. I have seveal DRAM cards, a FD controller and
a few other cards made by them and I'd like to do something with them.
Joe
Hi
Most of these like to use better letters such as the letter B.
Try setting things to the slowest baud on the terminal and then
you can watch realtime on a scope( like 110 ).
Get one of those light boxes. You still might be missing one
of the handshake lines that one machine needs that the other
doesn't. Get the box with the switches and jumpers. These are
in the $20 to $25 range and worth every penny.
Dwight
>
>I have a system that does an "autobaud" when you hit return to log in. If I
>hook up a VT220, it works at 7/1/E, 8/1/N, 7/1/O, etc. etc. no problem. If I
>hookup a Televideo 950, hitting return gets no response at all. This is NOT
>a DTE vs. DCE problem, because the televideo does work with the same system
>on a different type of serial port.
>
>I was thinking something might be brain damaged with parity
>generation/checking on this terminal. Is this a known issue of TV950's?
>About the only way I can find out whats going on is to dig out my datascope
>and see the start data & stop bits between the two when hitting return and
>see what is different.
>
>Any thoughts?
>
>Jay West
>
>---
>[This E-mail scanned for viruses by Declude Virus]
>
>
-----Original Message-----
From: Peter Matthewson [mailto:peter.matthewson@tiscali.co.uk]
Sent: 14 January 2004 21:27
To: 'andyh(a)andyh-rayleigh.freeserve.co.uk'
Subject: 77/68
Andy,
Just saw your note on 77/68 from the classic computing mailing list.
This made me smile; I can only see about 2 references to it that I can
find anywhere on the web.
My acquaintance with the 77/68 began when it featured in volume 1
edition 1 of Personal Computer World that I chanced upon in WH Smith in
Dewsbury, I think this was round about December 1977. I am not entirely
sure it was the UKs first home PC because I recall reading about a 4040
based system described in Wireless World which must have been a year or
so earlier.
I was so captivated by all this I withdrew all my savings bought the
bits and built one, for ?60. The 6800 microprocessor cost ?14 I recall.
I managed to get it working, I am not quite sure since I was a 15 year
old schoolkid with only a multimeter for test equipment, working in
isolation and did not really know what it was that I was building. The
main problem I had was with wiring the edge connector, the data bus was
in one bit order on the edge connector and the address bus in the
reverse bit order, a detail I didn?t understand the significance of
initially. It was about 2 years before I met anyone who had any idea
what I was talking about.
I extended the system with 1024 bytes of ram, built a keyboard and
cannibalised an old calculator display for peripherals. And I built a 32
bits per second tone burst modem for storage of programmes on cassette
tapes. The monitor program I wrote to drive all this took 256 bytes of
memory. Those were the days - he said wistfully.
Its still up in the loft. I almost feel inspired to get it out and fire
it up again!
Regards
Peter Matthewson
(re: http://www.cathodecorner.com/sonny.jpg)
Yes indeed, and I did! Man I wish I had all the junk I bought from
there...
-----Forwarded Message-----
From: David Forbes <>
To: Tom Jennings <tomj(a)wps.com>
Subject: Re: Would you buy a used PDP-8 from this man?
Date: 14 Jan 2004 13:37:17 -0700
Tom,
This photo is scanned in from the October 1982 issue of National
Geographic magazine, which I just found at the thrift store. It has
an article about The Chip, and another about Silicon Valley. Humorous
reading.
The guy with the bowtie is Sonny Monosson of American Used Computer
in Boston MA. I remember you saying that you used to go there now and
then in your youth.
I remember getting their ads in the late seventies, when I was using
PDP-11s in high school and college. I would drool over the
possibility of getting an obsolete 11 for home use, but the shipping
was so expensive back then. I imagine the power bill would be
something to behold also.
All I remember about the Heathkit LSI-11 I used at Optical Sciences
is that it was slower, instruction for instruction, than the Z-80 I
also used.
--
--David Forbes, Tucson, AZ
http://www.cathodecorner.com/
I am in need of one or two media for this diskdrive. Would become part
of a DG MP/200 system.
Would it be save to try without them?( the 6059 has a fixed platter
beneath the cartridge )
Jos dreesen, Zurich Switzerland
I'm still looking for a home for the big, heavy SGI I mentioned the other day.
It's going to /dev/null if I don't hear from anyone in Los Angeles who wants
it within the next few days :-(
-- Adam
