--- In midatlanticretro@yahoogroups.com, Dan Roganti <ragooman@...> wrote:
>
> Mike,
>
> I didn't see your link before and just took a look at your homebrew tester.
> It really needs some more work to tighten up the circuit before proceeding
> with further experiments.
> The important issue is to keep the wiring short, point to point...
Create a
> ground plane on there using the grid of plated through-holes...

Dan, I don't know if you read my most-recent post, before writing yours. Even
though I also mentioned crosstalk and noise and such - frankly, I don't think
that matters, with this tester. He's using a bunch of latches under software
control, to operate the RAM. It's going to run slowly enough, that any
switching-around noise won't last long enough to matter - much. (I suppose there
could be some situation where it does, if one worked at it.)

Seems to me...if he's to go to the trouble of building a proper, ground-planed,
short-wire fixture....he may as well design something that connects the RAM
right to the processor, and run it at CPU clock speeds. That is, under design
conditions.

THEN all that stuff you describe, matters. And THEN, with such a real-use kind
of tester, with "good" signals all around, then one can do some more serious
testing, and draw more serious conclusions.

Again - it's a reasonable bench-top, put-together-for-use, kind of tester. But
to use it to make claims about "self-healing RAM" phenomena, I think is pushing
its limitations.

Herb Johnson

--- In midatlanticretro@yahoogroups.com, Richard Cini <rich.cini@...> wrote:
>
> Bill --
>
> I didn't have time to pull both drives tonight but I did unmount the
> left-hand drive. Indeed it's a Shugart 801, SN# HV2633. As far as jumpers,
> DS1, T1, X, B and A are closed. EZ is set to Z. EI jumper is open. The
> 800/801 jumper is also open. There are black-ink markings on the PCB as
> follows: "25229.1", "1932", "48.2". I'll try to pull the other drive
> tomorrow and let you know if it's any different jumper-wise (assuming it's
> set for DS2).

I think the 25229 sounds like a Shugart 800/801 board model number.
>
> On a slightly-related note, I have two floppy controllers, a Morrow DJ2B and
> a VersaFloppy II, that I would consider using to build a new floppy system
> from. Is one better than the other for these drives? The Morrow board looks
> like 8"-only while the VF2 has both floppy connector types.
>
> Rich

the DJ2D-B is a decent enough 8-inch controller. Morrow docs are good.

The Versafloppy II is also a decent controller. My Web site has work of half a
dozen people with that controller, including John Monahan (s100computers.com).

http://www.retrotechnology.com/herbs_stuff/s_sd_vfii.html

Either ought to be able to run those Shugart 800's.

Herb Johnson

HI,

Boy, you guys are tough reviewers.  :-)

Other than testing speed, this test is about as complete as it can get.  Signals
look remarkably good, edges are fine with no ringing, overshoot or undershoot.

The nice thing about this tester is how quickly I was able to put it together. 
3 evenings for the 1101 tester and a couple of more hours to create the 2102
version.  Directly interfacing to a processor would have taken considerably
longer.

The other interesting thing is that I tested 200 1101 parts, with only 1 part
that I damaged during development of the test, failing.

I'm currently investigating whether tarnish is a contributing factor.

Regards,
MIke W.

--- In midatlanticretro@yahoogroups.com, "s100doctor" <hjohnson@...> wrote:
>
>
>
> --- In midatlanticretro@yahoogroups.com, Dan Roganti <ragooman@> wrote:
> >
> > Mike,
> >
> > I didn't see your link before and just took a look at your homebrew tester.
> > It really needs some more work to tighten up the circuit before proceeding
> > with further experiments.
> > The important issue is to keep the wiring short, point to point...
> Create a
> > ground plane on there using the grid of plated through-holes...
>
> Dan, I don't know if you read my most-recent post, before writing yours. Even
though I also mentioned crosstalk and noise and such - frankly, I don't think
that matters, with this tester. He's using a bunch of latches under software
control, to operate the RAM. It's going to run slowly enough, that any
switching-around noise won't last long enough to matter - much. (I suppose there
could be some situation where it does, if one worked at it.)
>
> Seems to me...if he's to go to the trouble of building a proper,
ground-planed, short-wire fixture....he may as well design something that
connects the RAM right to the processor, and run it at CPU clock speeds. That
is, under design conditions.
>
> THEN all that stuff you describe, matters. And THEN, with such a real-use kind
of tester, with "good" signals all around, then one can do some more serious
testing, and draw more serious conclusions.
>
> Again - it's a reasonable bench-top, put-together-for-use, kind of tester. But
to use it to make claims about "self-healing RAM" phenomena, I think is pushing
its limitations.
>
> Herb Johnson
>

deOxit might work


-------- Original Message --------
> From: "Burning Image" <visual_storytellers@...>
> Sent: Friday, November 16, 2012 10:40 AM
> To: "midatlanticretro@yahoogroups.com"
<midatlanticretro@yahoogroups.com>
> Subject: [midatlanticretro] Removal Suggestions? - Black Antistatic
Residue from the 70's
>
> I recently managed to find a NIB computer kit that arrived in today's
mail.  After carefully opening it, I noticed the 6800, 6821 and 6811 chips
were sitting on pads of black antistatic foam.  Flashing back a couple
decades, I thought about an 1861 chip that had its pins eaten by this
stuff.
>
> I managed to get the chips out of the crumbling material, but some of it
is still clinging to several pins.  As it already managed to devour the
gold plating on some pins, I don't want to apply too much pressure to
remove the remaining residue.
>
> Any suggestions on how to clean the pins?  It doesn't appear to be water
soluble.
>
> TNX!
>
> Cory - WA3UVV

DeOxit dissolves metallic oxides...not sure if it'd handle the goo
left behind by decomposing static-dissipative foam.  I'd try alcohol first.

           -Dave

On 11/16/2012 10:49 AM, B. Degnan wrote:
> deOxit might work
>
>
> -------- Original Message --------
>> From: "Burning Image" <visual_storytellers@...>
>> Sent: Friday, November 16, 2012 10:40 AM
>> To: "midatlanticretro@yahoogroups.com"
> <midatlanticretro@yahoogroups.com>
>> Subject: [midatlanticretro] Removal Suggestions? - Black Antistatic
> Residue from the 70's
>>
>> I recently managed to find a NIB computer kit that arrived in today's
> mail.  After carefully opening it, I noticed the 6800, 6821 and 6811 chips
> were sitting on pads of black antistatic foam.  Flashing back a couple
> decades, I thought about an 1861 chip that had its pins eaten by this
> stuff.
>>
>> I managed to get the chips out of the crumbling material, but some of it
> is still clinging to several pins.  As it already managed to devour the
> gold plating on some pins, I don't want to apply too much pressure to
> remove the remaining residue.
>>
>> Any suggestions on how to clean the pins?  It doesn't appear to be water
> soluble.
>>
>> TNX!
>>
>> Cory - WA3UVV
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>


--
Dave McGuire, AK4HZ
New Kensington, PA

I generally lightly scrape the black gunk clinging to the pins with a knife,
then swab them with a bit of isopropyl alcohol. If they don't break off during
the cleaning process, they can usually be inserted into sockets.

If they do break off, and they're ceramic side-brazed packages, I usually solder
them into a machine pin socket. Use a lot of water-soluble flux and wash well.
You can do the same with plastic DIP packages as long as the pins don't break
off flush with the IC body.

Thanks,
Jonathan

On Fri, 16 Nov 2012 10:49:21 -0500
"B. Degnan" <billdeg@...> wrote:

> deOxit might work
>
>
> -------- Original Message --------
> > From: "Burning Image" <visual_storytellers@...>
> > Sent: Friday, November 16, 2012 10:40 AM
> > To: "midatlanticretro@yahoogroups.com"
> <midatlanticretro@yahoogroups.com>
> > Subject: [midatlanticretro] Removal Suggestions? - Black Antistatic
> Residue from the 70's
> >
> > I recently managed to find a NIB computer kit that arrived in today's
> mail.  After carefully opening it, I noticed the 6800, 6821 and 6811 chips
> were sitting on pads of black antistatic foam.  Flashing back a couple
> decades, I thought about an 1861 chip that had its pins eaten by this
> stuff.
> >
> > I managed to get the chips out of the crumbling material, but some of it
> is still clinging to several pins.  As it already managed to devour the
> gold plating on some pins, I don't want to apply too much pressure to
> remove the remaining residue.
> >
> > Any suggestions on how to clean the pins?  It doesn't appear to be water
> soluble.
> >
> > TNX!
> >
> > Cory - WA3UVV
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>

"Goo Gone" did wonders removing some disintegrating foam insulation from an
Apple Imagewriter printer i recently did some restoration work on.  It still
took some mechanical effort, so I'm not so sure how it would work in your case
with IC pins.

Regards,
Mike Willegal

--- In midatlanticretro@yahoogroups.com, Burning Image <visual_storytellers@...>
wrote:
>
> I recently managed to find a NIB computer kit that arrived in today's mail.
 After carefully opening it, I noticed the 6800, 6821 and 6811 chips were
sitting on pads of black antistatic foam.  Flashing back a couple decades, I
thought about an 1861 chip that had its pins eaten by this stuff.
>
> I managed to get the chips out of the crumbling material, but some of it is
still clinging to several pins.  As it already managed to devour the gold
plating on some pins, I don't want to apply too much pressure to remove the
remaining residue.
>
> Any suggestions on how to clean the pins?  It doesn't appear to be water
soluble.  
>
> TNX!
>
> Cory - WA3UVV
>

--- On Fri, 11/16/12, Systems Glitch <systems.glitch@...> wrote:

> If they do break off, and they're ceramic side-brazed
> packages, I usually solder them into a machine pin socket.
> Use a lot of water-soluble flux and wash well. You can do
> the same with plastic DIP packages as long as the pins don't
> break off flush with the IC body.

Even if they do break off flush with the IC body, it's possible to chisel away
at the plastic package to get enough of the lead exposed to solder to. Remember
that the die of the chip is just in the very center, the rest of the package is
just leadframe. You can chisel into it quite a bit.

That foam is evil and corrosive - I don't have any specific hints for removing
it, but something I've had a lot more experience with is tarnished IC legs. Some
chips (especially the Namco customs from 80's era arcade games) have legs that
will tarnish and blacken, and get very brittle and crumble off. Sometimes even
flush with the package (and then you have to do the above). But the black
tarnish isn't conductive, and doesn't even take solder well, so it has to be
removed. In this case, Tarn-X does a fantastic job dissolving it. Be sure to
clean it again with isopropyl alcohol to get the Tarn-X off, it's a pretty nasty
chemical. Smells awful too.

TI branded logic from the 70's has a very similar problem, but in that case it's
just standard TTL and not worth the effort to salvage.

-Ian

My pristine original IBM PC green-phosphor CRT, the one with the SUPER
long-persistence phosphor, just took a dive down a flight of stairs.  I
am pretty upset about that.

   Does anyone have one of these that they might be willing to turn loose of?

               -Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

On 11/16/2012 1:10 PM, Dave McGuire wrote:
>    My pristine original IBM PC green-phosphor CRT, the one with the SUPER
> long-persistence phosphor, just took a dive down a flight of stairs.  I
> am pretty upset about that.
>


jeesshh, I can't leave you alone for a minute, slacker ;)

On 11/16/2012 01:24 PM, Dan Roganti wrote:
>>    My pristine original IBM PC green-phosphor CRT, the one with the SUPER
>> long-persistence phosphor, just took a dive down a flight of stairs.  I
>> am pretty upset about that.
>>
>
> jeesshh, I can't leave you alone for a minute, slacker ;)

   Man, it was bad.  The monitor was in a plastic bin, and was going down
on the hand truck with two other bins.  I lost my footing two steps from
the bottom and the pile cascaded down.  The monitor housing shattered
and the CRT neck got whacked.

   It's very upsetting, doubly so because I can only blame myself.  That
monitor, and the 5160 it went with, was absolutely *pristine*.  I really
need to find another one.

               -Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

On Fri, 16 Nov 2012, Dave McGuire wrote:

>    My pristine original IBM PC green-phosphor CRT, the one with the SUPER
> long-persistence phosphor, just took a dive down a flight of stairs.  I
> am pretty upset about that.

     At least it didn't hit you in the head (Hi, Sellam).

     I need a CRT for a DEC VT-320, because I stupidly tried to straighten
one of the pins with a needlenose (ping, hiss).


Mike Loewen 		 mloewen@...
Old Technology       http://sturgeon.css.psu.edu/~mloewen/Oldtech/

InfoAge finally got electrical power -- about three weeks post-Sandy. So we are
re-opening this Sunday.

PS - I'm told there is plenty of clean-up work to do Saturday. All are welcome
to come help.

--- In midatlanticretro@yahoogroups.com, Dave McGuire <Mcguire@...> wrote:
>
>
>   My pristine original IBM PC green-phosphor CRT, the one with the SUPER
> long-persistence phosphor, just took a dive down a flight of stairs.  I
> am pretty upset about that.
>
>   Does anyone have one of these that they might be willing to turn loose of?

I have two green-screen IBM PC monitors, I can offer one, we can work a deal.
How "long" is long-persistence? I've forgotten what's "normal persistance" for
them. If there's a particular model number I can check that.

Contact me privately, Dave. I will likely be at Infoage on Monday, if bringing
one would help you that way; otherwise I can ship from my location.

Herb

> --- In midatlanticretro@yahoogroups.com, Burning Image <visual_storytellers@>
wrote:

>..., I noticed the 6800, 6821 and 6811 chips were sitting on pads of black
antistatic foam.
> > I managed to get the chips out of the crumbling material, but some of it is
still clinging to several pins.  As it already managed to devour the gold
plating on some pins, I don't want to apply too much pressure to remove the
remaining residue.
> >
> > Any suggestions on how to clean the pins?  It doesn't appear to be water
soluble.  

--- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
>
> "Goo Gone" did wonders removing some disintegrating foam insulation from an
Apple Imagewriter printer i recently did some restoration work on.  It still
took some mechanical effort, so I'm not so sure how it would work in your case
with IC pins.
>
> Regards,
> Mike Willegal

I'm working up an analysis of this black antistatic foam stuff. There's many
reports of damaged chips from the degradation of this material. I want my site
to get on top of this.  I don't have a document ready to publish, but here's
some bits of information:

> This patent application for antistatic foam looks more reasonable.
> http://www.google.com/patents/US5567740
> Here's an excerpt:
>
> "This foam is produced by combining conventional polyurethane foam-forming
> reactants and an effective amount of an antistatic agent such as
> tetracyanoquinodimethane (TCNQ) or sodium perchlorate under foam-forming
> conditions. In one preferred embodiment, the conductive foam is
> subsequently reticulated by momentary exposure to a flame front."

Another description is "polyolefin plastic resins"; "LDPE" (low density
polyethylene); "EVA" (Ethylene-vinyl acetate). I've heard rumors that the
conducting content is lamp black, burned sugar (acid not heat). There's likely
many ways this stuff is/was produced.

If the base material is a kind of plastic, then something like "Goo Gone" - in
large part made of toluene - may dissolve it. Also: the traditional "gag" at an
auto shop is to ask the new guy/gal to carry gasoline in a styrofoam cup. Of
course, it dissolves the cup FAST.

  Handle these flammable and liver-damaging substances with caution. Please
report results here, and with permission I'll quote content posted accordingly.

Herb Johnson

--- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
>
>
> HI,
>
> Boy, you guys are tough reviewers.  :-)
>
> Other than testing speed, this test is about as complete as it can get. 
Signals look remarkably good, edges are fine with no ringing, overshoot or
undershoot.
>
> The nice thing about this tester is how quickly I was able to put it together.
3 evenings for the 1101 tester and a couple of more hours to create the 2102
version.  Directly interfacing to a processor would have taken considerably
longer.
>
> The other interesting thing is that I tested 200 1101 parts, with only 1 part
that I damaged during development of the test, failing.
>
> I'm currently investigating whether tarnish is a contributing factor.
>
> Regards,
> MIke W.

I largely agree with you - this is a nice bit of work. One could test most any
bit of logic with variations of this Apple II code and hardware. And it's not
hard to do the same logic, with a Z80, a 6800, etc. It might be fun to use a
microKIM, could even use most of your code! Plus, the microKIM could probably
implement an at-speed tester too, plenty of address space "open". Even I, "the
S-100 guy", have one of those.

I'm curious...I think, reading your read/write subroutine, you are probably
running the RAM at say 20-25 microseconds? Given an Apple II at 1MHz? If you
looked at the signals, you probably know how fast your scope was sweeping to see
one access time.

I'm inspired to make something like this, if I get a Z80 prototype running next
year. Thanks for keeping the 1970's on the bleeding edge again. Well....maybe
the leaking edge.....;)

Herb Johnson

I've been told by someone who worked in the industry "back then" that the good
stuff was synthetic foam with lamp black/carbon/graphite/et c., but that the
lousy stuff was just sugar reduced to carbon with fuming sulphuric acid and
sliced into sheets. The foam was, of course, washed after production, but
presumably some of the acid remained. Fuming sulphuric acid would be 98% or
higher concentration (it's hydroscopic, so hard to keep it above that).

One can try the sulphuric acid reduction at home with table sugar and sulphuric
acid drain opener. It proceeds slower than if one uses fuming acid. It does
indeed make a carbon foam, which like the foam that dissolves component leads,
squishes and does not return to its original shape/thickness. Essentially the
sulphuric acid, which is a very good dessicant at high concentrations, strips
the hydrogen and oxygen from sugar as water, leaving only the carbon. Steam is
created as the reaction heats up, resulting in foaming.

Forrest M. Mims, III also claims that the black foam is made with carbon in one
of his "Engineer's Mini-Notebooks." There is a project that involves building
load cells for sensing pressure with a bit of carbon antistatic foam sandwiched
between two pennies in a piece of plastic tube. The further compressed, the less
resistance.

Thanks,
Jonathan

On Sat, 17 Nov 2012 00:37:50 -0000
"s100doctor" <hjohnson@...> wrote:

> > --- In midatlanticretro@yahoogroups.com, Burning Image
<visual_storytellers@> wrote:
>
> >..., I noticed the 6800, 6821 and 6811 chips were sitting on pads of black
antistatic foam.
> > > I managed to get the chips out of the crumbling material, but some of it
is still clinging to several pins.  As it already managed to devour the gold
plating on some pins, I don't want to apply too much pressure to remove the
remaining residue.
> > >
> > > Any suggestions on how to clean the pins?  It doesn't appear to be water
soluble.  
>
> --- In midatlanticretro@yahoogroups.com, "Mike" <mike@...> wrote:
> >
> > "Goo Gone" did wonders removing some disintegrating foam insulation from an
Apple Imagewriter printer i recently did some restoration work on.  It still
took some mechanical effort, so I'm not so sure how it would work in your case
with IC pins.
> >
> > Regards,
> > Mike Willegal
>
> I'm working up an analysis of this black antistatic foam stuff. There's many
reports of damaged chips from the degradation of this material. I want my site
to get on top of this.  I don't have a document ready to publish, but here's
some bits of information:
>
> > This patent application for antistatic foam looks more reasonable.
> > http://www.google.com/patents/US5567740
> > Here's an excerpt:
> >
> > "This foam is produced by combining conventional polyurethane foam-forming
> > reactants and an effective amount of an antistatic agent such as
> > tetracyanoquinodimethane (TCNQ) or sodium perchlorate under foam-forming
> > conditions. In one preferred embodiment, the conductive foam is
> > subsequently reticulated by momentary exposure to a flame front."
>
> Another description is "polyolefin plastic resins"; "LDPE" (low density
polyethylene); "EVA" (Ethylene-vinyl acetate). I've heard rumors that the
conducting content is lamp black, burned sugar (acid not heat). There's likely
many ways this stuff is/was produced.
>
> If the base material is a kind of plastic, then something like "Goo Gone" - in
large part made of toluene - may dissolve it. Also: the traditional "gag" at an
auto shop is to ask the new guy/gal to carry gasoline in a styrofoam cup. Of
course, it dissolves the cup FAST.
>
>  Handle these flammable and liver-damaging substances with caution. Please
report results here, and with permission I'll quote content posted accordingly.
>
> Herb Johnson
>
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>

Interesting....the S800's in the Intel MDS 720 photoed on my web site also have
significantly different jumpers drive 0 vs. drive 1.  Maybe that's how it's
done, or the boot drive has a lot of differences that the non boot drive.  I
wonder what this drive was used for.
bd

-------- Original Message --------
> From: "Richard Cini" <rich.cini@...>
> Sent: Friday, November 16, 2012 11:19 PM
> To: "midatlanticretro@yahoogroups.com" <midatlanticretro@yahoogroups.com>
> Subject: Re: [midatlanticretro] Lobo floppy drives
>
> Bill --
>
> I finished examining and cleaning the interior of the drive enclosure this
> evening. I took note of the jumpers on both drives ‹ interestingly there
> were many differences between the jumper settings, other than what would be
> expected (i.e., the drive select and the termination).
>
> Here are the jumper settings:
>
> Drive0: installed ‹ DS1-T1-X-B-A-Z
> Drive1: installed ‹ T2-HL-800-DS2-T3-T4-T5-T6-T1-X-B-A-Z (this drive is at
> the end of the cable)
>
> Drive1 also had a drive_ready modification which resulted in pin22 being put
> on pin4 of the interface connector (jumper R cut; wire from R to pin 4).
>
> Given this configuration I'm not entirely sure what system this might have
> been used in since the drives are set so differently. So, I reset the
> jumpers per the CompuPro Disk 1 instructions and once I build a cable, I can
> try it on my IMSAI. Overall the drives look very clean and free from
> excessive dust.
>
> Rich
>
> --
> Rich Cini
> Collector of Classic Computers
> Build Master and lead engineer, Altair32 Emulator
> http://www.classiccmp.org/cini
> http://www.classiccmp.org/altair32
>
>
> From:  B Degnan <billdeg@...>
> Reply-To:  "midatlanticretro@yahoogroups.com"
> <midatlanticretro@yahoogroups.com>
> Date:  Wednesday, November 14, 2012 9:46 AM
> To:  "midatlanticretro@yahoogroups.com" <midatlanticretro@yahoogroups.com>
> Subject:  Re: [midatlanticretro] Lobo floppy drives
>
>
>
>
>
>
> Sorry, I mean jumpers on the drives in the enclosure.  Here is an
> example..
>
> http://vintagecomputer.net/intel/MDS-720/
>
> Bill
>
> -------- Original Message --------
> > From: "B. Degnan" <billdeg@... <mailto:billdeg%40degnanco.com> >
> > Sent: Wednesday, November 14, 2012 9:30 AM
> > To: midatlanticretro@yahoogroups.com
> <mailto:midatlanticretro%40yahoogroups.com>
> > Subject: Re: [midatlanticretro] Lobo floppy drives
> >
> > It might be a pain, but if you have a chance to take a picture of the
> > jumpers on the board, I'd be interested to see what you have.  I just did
> a
> > set of SA800's from an Intel MDS.  I expect yours to be completely
> > different.
> > bd
> >

I'm hoping it's a trs 80 or maybe an actual LOBO computer.

-------- Original Message --------
> From: "Richard Cini" <rich.cini@...>
> Sent: Saturday, November 17, 2012 8:35 AM
> To: "midatlanticretro@yahoogroups.com"
<midatlanticretro@yahoogroups.com>
> Subject: Re: [midatlanticretro] Lobo floppy drives
>
> Bill --
>
> I emailed the original seller to see if he knows the history of the
unit.
> When I hear back I'll let you know.
>
> Rich
>
> --
> Rich Cini
> Collector of Classic Computers
> Build Master and lead engineer, Altair32 Emulator
> http://www.classiccmp.org/cini
> http://www.classiccmp.org/altair32
>
>
> From:  B Degnan <billdeg@...>
> Reply-To:  "midatlanticretro@yahoogroups.com"
> <midatlanticretro@yahoogroups.com>
> Date:  Friday, November 16, 2012 11:47 PM
> To:  "midatlanticretro@yahoogroups.com"
<midatlanticretro@yahoogroups.com>
> Subject:  Re: [midatlanticretro] Lobo floppy drives
>
>
>
>
>
>
> Interesting....the S800's in the Intel MDS 720 photoed on my web site
also
> have significantly different jumpers drive 0 vs. drive 1.  Maybe that's
how
> it's done, or the boot drive has a lot of differences that the non boot
> drive.  I wonder what this drive was used for.
> bd
>
> -------- Original Message --------
> > From: "Richard Cini" <rich.cini@...
<mailto:rich.cini%40verizon.net> >
> > Sent: Friday, November 16, 2012 11:19 PM
> > To: "midatlanticretro@yahoogroups.com
> <mailto:midatlanticretro%40yahoogroups.com> "
<midatlanticretro@yahoogroups.com
> <mailto:midatlanticretro%40yahoogroups.com> >
> > Subject: Re: [midatlanticretro] Lobo floppy drives
> >
> > Bill --
> >
> > I finished examining and cleaning the interior of the drive enclosure
this
> > evening. I took note of the jumpers on both drives ? interestingly
there
> > were many differences between the jumper settings, other than what
would be
> > expected (i.e., the drive select and the termination).
> >
> > Here are the jumper settings:
> >
> > Drive0: installed ? DS1-T1-X-B-A-Z
> > Drive1: installed ? T2-HL-800-DS2-T3-T4-T5-T6-T1-X-B-A-Z (this drive is
at
> > the end of the cable)
> >
> > Drive1 also had a drive_ready modification which resulted in pin22
being put
> > on pin4 of the interface connector (jumper R cut; wire from R to pin
4).
> >
> > Given this configuration I'm not entirely sure what system this might
have
> > been used in since the drives are set so differently. So, I reset the
> > jumpers per the CompuPro Disk 1 instructions and once I build a cable,
I can
> > try it on my IMSAI. Overall the drives look very clean and free from
> > excessive dust.
> >
> > Rich
> >
> > --
> > Rich Cini
> > Collector of Classic Computers
> > Build Master and lead engineer, Altair32 Emulator
> > http://www.classiccmp.org/cini
> > http://www.classiccmp.org/altair32
> >

On Sat, Nov 17, 2012 at 06:52:47AM -0000, Douglas wrote:
> The video intensity knob in the back changes the text brightness but
> does not affect the
> brightness of the abnormality.
>
Nornmally monitors have two adjustments, brightness and contrast or
some similar name. Roughly brighness sets the black level/backgrond and
constrast the gain so it mostly effects text brightness. It sounds like your
monitor only has the contrast control external.

This link indicates that the monitor does have an internal brighness pot.
Adjusting it may fix your problem. People with Kaypro experiance may
chime in with better advice.
http://newsgroups.derkeiler.com/Archive/Comp/comp.os.cpm/2005-08/msg00052.html

--- In midatlanticretro@yahoogroups.com, "Douglas" <touchetek@...> wrote:
>
> For a few seconds, the background is normal;   nice and dark.
> The text stays the same.
> The the abnormal retracing fades up.


> (some just say swap out the video board...)

Wow, that's great advice, I would have said swap out the computer ;)
(sarcasm).

Seriously, here's what I would do to start breaking down the problem.
Two roads.
1. the problem occurs much after the capacitors charge, the picture tube warms
up, so I would guess some part is getting excessively hot.  Get some cold spray
and gently spray some area of the video board.  Spray with the straw 2 or 3"
from board.  Cover the whole board a few times, do this within 30 seconds of the
problem appearing.  If there are no changes, power down, repeat but be more
agressive with cold spray, say 1".  If you do encounter a change, wait for the
problem and find the component(s) that are causing it.  When you find the
component, you'll decide then what to do about it? replace? supplement a heat
sink? trace the heat problem to some other source ie voltage too high?

2. Scope the pins to the CRT.  In general, there could be 3 grid voltages I
think they were Bias, Focus and Video?  Then there's the cathode and the heater.
I think most of these voltages are low, perhaps the bias voltage might be high?
but nothing a scope can't handle.  Stay away from the high voltage line that is
a single wire to the side of the tube, here you can find 15,000 volts (up to 35K
on large colour TV's).  While scoping, look for which line (if any) shifts it's
voltage.  If none of the lines shift voltage, then the problem could be with the
high voltage or the picture tube?  But I've never heard of a picture tube
causing this problem and a change in high voltage typically results in a loss of
focus.

PS. I have a Kaypro in my repair queue too, but it will be a while before I get
to it.

Good luck!
Josh

--- In midatlanticretro@yahoogroups.com, David Gesswein <djg@...> wrote:
>
> On Sat, Nov 17, 2012 at 06:52:47AM -0000, Douglas wrote:
> > The video intensity knob in the back changes the text brightness but
> > does not affect the
> > brightness of the abnormality.
> >
> This link indicates that the monitor does have an internal brighness pot.
> Adjusting it may fix your problem. People with Kaypro experiance may
> chime in with better advice.
> http://newsgroups.derkeiler.com/Archive/Comp/comp.os.cpm/2005-08/msg00052.html
>

Hi Doug,  Scratch my advice, I think David has the right stuff here.

Cheers,
Josh