30 May
2002
30 May
'02
5:36 a.m.
From: "Pat Finnegan"
<pat(a)purdueriots.com>
On Thu, 30 May 2002, Glen Goodwin wrote:
I'm starting to have some second thoughts about how I'm going to do this.
I'm considering an external 'black box' that will connect to a PPP server
on one end and have a RS-232 connection on the other that will provide
something like a serialized verion of BSD's sockets. I'm also thinking
about implementing a raw tcp port that would connect to an extra RS-232
port [optionally password protected] that could be used to attach to the
system's console, and replicate it on the other end of the network.
Right now I'm looking at either a Z80 with 32k of ram, 16k of flash, a CTC
and one or two DUARTS, or a uC that'll provide as much of that in hardware
as possible. PICs are nice, but generally seem to have too little memory
for TX/RX buffers, and Basic stamps are too slow. (and who wants to
program in BASIC anyways?)
Any suggestions on a good uC to use?
-- Pat
Hi
Although, I don't care for BASIC, there is a company that
is about to release a stamp like board with a BASIC that is
benching at 500 to 1500 times faster than the original PIC stamps.
It gets it's speed from having a better memory model. You
don't have to program in BASIC with it. In fact, the BASIC
is written in Forth that underlies the BASIC. From what I'm
told, you can access the Forth. If Forth isn't your cup of
tea, most all Forths have been able to access the raw assembly
level without using yet another tool. The processor is
based on the 8051 instruction set but it one or two clocks
per instruction instead of 12 to one. Of course, it runs
in the tens of megahertz. Mixed assembly and Forth often
makes a good optimization of speed and memeory size.
Later
Dwight
From: Pat
Finnegan <pat(a)purdueriots.com>
What I'm looking to do is provide a (small)
SLIP or PPP based TCP/IP
stack
for a machine that will stay resident and can be
used by CP/M 2.2 [or
perhaps MP/M II] user programs.
Pat --
I would be extremely interested to learn of your progress in this area.
Please keep us posted, or contact me off-list. 
30 May
30 May
7:33 a.m.
New subject: HP ScanJet ADF
I recently bought a used HP 6300C C7670 scanner w/ADF where the ADF was
advertised as non-functional. I figured that there shouldn't be too much
wrong with it and after looking into it, it seems to be complete and not
too heavily worn, so I hope to fix it.
Does anyone have any service manual information on these?
--tnx
--tom
8:58 a.m.
New subject: HP ScanJet ADF
On Thu, 30 May 2002, Tom Uban wrote:
I recently bought a used HP 6300C C7670 scanner w/ADF
where the ADF was
advertised as non-functional. I figured that there shouldn't be too much
wrong with it and after looking into it, it seems to be complete and not
too heavily worn, so I hope to fix it.
Does anyone have any service manual information on these?
If you come up with any service manuals, I'd definitely like a copy
myself.
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
31 May
31 May
4:50 a.m.
New subject: HP ScanJet ADF
So after calling the HP parts desk to see about a replacement PCB for
my ADF, the person tells me that I can only buy a complete replacement ADF,
not individual parts...
I guess I will just proceed with repairing the board. The 24v input seems
to be shorted to ground -- that shouldn't be to difficult to find.
--tom
At 02:33 PM 5/30/02 -0500, you wrote:
I recently bought a used HP 6300C C7670 scanner w/ADF
where the ADF was
advertised as non-functional. I figured that there shouldn't be too much
wrong with it and after looking into it, it seems to be complete and not
too heavily worn, so I hope to fix it.
Does anyone have any service manual information on these?
--tnx
--tom
5:32 a.m.
New subject: HP ScanJet ADF
Tom Uban wrote:
I guess I will just proceed with repairing the board.
The 24v input seems
to be shorted to ground -- that shouldn't be to difficult to find.
Just a suggestion: I fixed an HP 1980B oscilloscope that had a shorted
power supply by replacing a shorted tantalum capacitor. Tantalums
tend to go short-circuit for no good reason, and result in the
short-to-ground symptom that you mention.
--
John Honniball
coredump(a)gifford.co.uk
6:03 a.m.
New subject: HP ScanJet ADF
Another problem to keep an eye out for are tantalums that were inserted
onto the board *backwards*, with the polarities wrong.
I saw this on a few different production boards from different
manufacturers. It seems the power supplies work perfectly fine for a while,
and short out later on in life.
Replacing the capacitor fixed the problems.
- Matt
At 06:32 PM 5/31/2002 +0100, you wrote:
Tom Uban wrote:
Matthew Sell
Programmer
On Time Support, Inc.
www.ontimesupport.com
(281) 296-6066
Join the Metrology Software discussion group METLIST!
http://www.ontimesupport.com/subscribe_t&c.htmlhtml.
"One World, One Web, One Program" - Microsoft Promotional Ad
"Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitler
Many thanks for this tagline to a fellow RGVAC'er...
I guess I will just proceed with repairing the
board. The 24v input seems
to be shorted to ground -- that shouldn't be to difficult to find.
Just a suggestion: I fixed an HP 1980B oscilloscope that had a shorted
power supply by replacing a shorted tantalum capacitor. Tantalums
tend to go short-circuit for no good reason, and result in the
short-to-ground symptom that you mention.
--
John Honniball
coredump(a)gifford.co.uk
7:22 a.m.
New subject: HP ScanJet ADF
Close call. The problem turned out to be a shorted SMD bypass capacitor,
not a tantalum. I've seen thru-hole tantalums fail in the past, but I
haven't had much experience with SMD repair (until now). I checked the
capacitor after removal to be sure that it wasn't just a solder problem,
but it was in fact shorted! Fortunately, I was able to salvage the two
other SMD parts, one SO-8 and one P-DSO-24-3, which I had also removed
in order to verify that they were not the cause of the short. I had
considered just cutting the legs to remove them, but used a pointed
scriber to lift the legs instead. After cleaning the solder off of both
the board and the legs, and then straightening the legs back to the
proper pitch and height, I was able to replace them onto the PCB ok.
After putting the PCB back into the ADF and hooking it all together,
the scanner now operates properly with the ADF -- woohoo!!!
I guess that I just saved some more space in a landfill somewhere for
someone elses ADF unit, because HP won't sell parts for these units.
Imagine what HP will do with anything that Compaq managed to save from
DEC (though I don't imagine that would be much)...
Thanks for everyone's advice!
--tom
At 06:32 PM 5/31/02 +0100, you wrote:
Tom Uban wrote:
I guess I will just proceed with repairing the
board. The 24v input seems
to be shorted to ground -- that shouldn't be to difficult to find.
Just a suggestion: I fixed an HP 1980B oscilloscope that had a shorted
power supply by replacing a shorted tantalum capacitor. Tantalums
tend to go short-circuit for no good reason, and result in the
short-to-ground symptom that you mention.
--
John Honniball
coredump(a)gifford.co.uk
9:16 a.m.
New subject: HP ScanJet ADF
To: cctalk(a)classiccmp.org
From: Tom Uban <uban(a)ubanproductions.com>
Subject: Re: HP ScanJet ADF
Reply-to: cctalk(a)classiccmp.org
Date: Fri, 31 May 2002 14:22:02 -0500
Close call. The problem turned out to be a shorted SMD
bypass capacitor,
not a tantalum. I've seen thru-hole tantalums fail in the past, but I
Ditto. Except that cap died in modern ADSL modem i'm renting from
bell. Fixed that thing and used a junk VCR transformer to power
modem because that SMD capacitor burned out that original transformer
wart even there is a fuse AFTER that capacitor. Brillent.
So if someone sees my 'puter tower w/ intact VCR cabinet besides it
w/ contents gutted, wires trailing out of that tape opening. That's
power for my modem. :-)
Cheers,
Wizard
10:36 a.m.
New subject: HP ScanJet ADF
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3:01 p.m.
New subject: HP ScanJet ADF
At 11:36 PM 5/31/02 +0100, you wrote:
This is the kind of situation in which an HP547A current probe is
most handy. You can easily follow the high current path with it.
Of course, you need to monitor (and limit) the current supplied to
the board under test.
carlos.
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org
I guess I will
just proceed with repairing the board. The 24v input seems
to be shorted to ground -- that shouldn't be to difficult to find.
Probably a shorted decoupling capacitor (if it's a 'dead short' or close
to one). I have been known to carefully cut power traces to find out
which section is shorted, and then home in on the problem. Or you can
desolder components to test them.
Don't use the trick I once saw recomended of applying a high current
(10's of amps) PSU to attempt to burn out the short. Something will burn
out, it's true, but it will just be the weakest connection, not
necessarily the shorted component.
-tony 
1 Jun
1 Jun
3:54 a.m.
New subject: locating shorts Re: HP ScanJet ADF
Probably a shorted decoupling capacitor (if it's a
'dead short' or close
to one). I have been known to carefully cut power traces to find out
which section is shorted, and then home in on the problem.
That's the way that I've traced shorts down. However since then I've bought
a HP Current probe, they're supposed to be able to trace a short down the correct
path. I've never had a need for it since I bought it so I dont know how well it works.
Has anyone had any experience using one?
Or you can
desolder components to test them.
Don't use the trick I once saw recomended of applying a high current
(10's of amps) PSU to attempt to burn out the short. Something will burn
out, it's true, but it will just be the weakest connection, not
necessarily the shorted component.
OUCH! I've never seen that recommended and I sure wouldn't try it. In my
experience, a hard short will completely remove the circuit runs from the board. And those
can be a real pain to replace, I've seen some runs disappear so completely that it was
nearly impossible to tell that they were ever there.
Joe
7:12 a.m.
New subject: locating shorts Re: HP ScanJet ADF
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11 comments
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participants (9)
-
ard＠p850ug1.demon.co.uk -
carlos_murillo＠epm.net.co -
coredump＠gifford.co.uk -
dwightk.elvey＠amd.com -
foo＠siconic.com -
jpero＠sympatico.ca -
msell＠ontimesupport.com -
rigdonj＠cfl.rr.com -
uban＠ubanproductions.com