Does anyone have a circuit diagram for a DRI 7200 floppy? This is a
double-sided 8" floppy drive. I have a pair of them in a Baydel box, and
Drive 1 has faulty electronics (I've checked the cables, connectors, and
jumpers, and switched the boards just to be sure). It won't read (it does
seek, load heads, detect disk, etc). I'd like to fix it, but tracing out
the circuit isn't my first wish.
--
Pete Peter Turnbull
Network Manager
University of York
On Jan 21, 10:45, Mark Tapley wrote:
> ..."heater?" IIRC, Pete said these transistors work up to 100 MHz and
they
> are being used to drive *heaters?* Does that mean the other 17 or so
> connections to the print head carry the which-pixel information and
> whatever (piezoelectric?) pulse it takes to actually send out the squirt
of
> ink? Oy. Or are there 8 heaters and one for the jet pulse, and the thin
17
> carry the jet-selection info? Maybe I am going to be be interested enough
> to trace this whole circuit out. Or maybe I should just shred one of the
> print heads to see what's inside it.
The 100MHz just means it's possibly over-specced -- but probably not by
much. The head travels at a fair speed over the paper and the dots are
small, so you want the jets to turn on and off fairly fast; and you want a
nice square wave (or at least fast rise and fall times) while you're doing
it, not some ragged aproximation to a bent sine wave. I don't know much
about inkjets, but isn't the very rapid and very localised heating part of
what generates the jet?
--
Pete Peter Turnbull
Network Manager
University of York
Today whilst picking up a copy of Wireless World I noticed a new publication.
"Electronics and Technology Cosmos International"
Editor Constantine Delenardo
196 High Road, Wood Green, London N22 8HH
So what I here you say. Well, the January edition is 72 pages of electronics
with no adverts, not even one. There is no mention of a publisher and Google
turned up zip. Has anyone else seen this on the news stands ?
Topics covered:
Going from Dual to single supply op amp operation
Low voltage logic Families and Mixed Voltage Interfacing Techniques. Part 1
Data Interface Standards. Part 1.
Introduction to the Theory and Design of Audio Power Amplifiers. Part 1
Cache Memory for Computer Systems. Part 1
Charge Pumps Simplify Portable Designs
Simplified Bipolar Transistor Models & how to use them
It is very well written and provides a clear introduction to basic principles.
Rather than practical articles it seems to be more of a reference book
with a lot of worked examples. Definitely worth a read.
Chris
> -----Original Message-----
> From: Dave McGuire [mailto:mcguire@neurotica.com]
> I've got modern Alphas. Crays too. That's not the point. :)
Crays? That would be nice. Anyone have an EL 92 they'd like to get rid of? ;)
Regards,
Chris
Christopher Smith, Perl Developer
Amdocs - Champaign, IL
/usr/bin/perl -e '
print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n");
'
Toth asked:
>Are there 3 indentations around the edges of the fasteners? If so, these
>could be a type of Japanese fastener often found in mid '80s to early '90s
>video game systems. Bits that fit those kinds of fasteners are available,
>at about $1.50-$2 each, and they come in 2 different sizes.
Hmmm - will look again. I was specifically looking for anything I could get
purchase on to turn the things, though, and did not see it.
---------------
Tony said:
>Hnag on... I thought it was one printhead heater that was out. In which
>case it's likely that 8 of the 9 transistors are still fine.
Right ... but I don't know which one. I was hoping to end up unsoldering
them all, and finding the bad one by the first-order test, then putting all
but that one back and ordering a single replacement. In which case I might
as well start off with just the four I couldn't get my VOM onto during the
in-use testing I tried. I did not count on destroying components as I
pulled them, however. Glad I only tried 4.
..."heater?" IIRC, Pete said these transistors work up to 100 MHz and they
are being used to drive *heaters?* Does that mean the other 17 or so
connections to the print head carry the which-pixel information and
whatever (piezoelectric?) pulse it takes to actually send out the squirt of
ink? Oy. Or are there 8 heaters and one for the jet pulse, and the thin 17
carry the jet-selection info? Maybe I am going to be be interested enough
to trace this whole circuit out. Or maybe I should just shred one of the
print heads to see what's inside it.
>Do you know
>if you tested one that was related to the dead row of pixels?
No. I *thought* so, from the in-operation tests and locations on the
ribbon-cable connector, but since I still have not got the PS working, I
can't confirm that by trying to print again with the 4 transistors removed
- which is the only way I'd believe at this point.
BTW, would *that* toast anything?
>It won't be. A diode junction is not an ohmic conductor, and there's no
>reason why it should show the same 'resistance' under different test
>conditions (such as changing the range on the VOM).
Figured, which is why I put quotation marks around "resistance".
>In the end it'll be to a +ve supply line, but there might be other
>transistors or current sensing circuitry in the way. However, since this
>is common to all pixels, it's not a problem (yet).
'cause I haven't tried to test or disassemble it (yet) >:-)
>Probably resistors (read the numbers like you would the numbers on a
>capacitor -- so 151 -> 15*10^1 = 150 Ohms, and so on). I'd expect a
>resistor from base to emitter and another resistor from base to some kind
>of open-collector output (maybe a discrete transistor, maybe a chip).
I'll check, but that's consistent with what I've seen so far, I think.
>The fault, of course, might be further back in the circuitry, so you
>might have to trace out this array of components.
More havoc to wreak...
>Any depressions in those heads at all? Any way a tool could engage with them?
I don't think so. I'll have one more look before I try the soldering iron
(didn't get to it this weekend).
>Oh, it can't be that complicated. After all, there are likely to be 9
>identical stages. I would conentrate on the base of the power
>transistors. What connects there, what does it connect to.
I don't see 9 identical groups of components anywhere else. There are
several large DIP packages, one of which I'll bet I run into on the far
side of the surface-mount things.
>This 'surface mount array' : What does it contain? Any more transistors?
>Any open-collector driver chips nearby?
The only things I saw were the little (?) resistors described earlier. I
didn't look at the chips nearby - I'll try that next chance I get.
>Unlikely. The voltage is not going to damage parts of this printer, or
>any other classic computer you're likely to be working on.
OK, that's reassuring.
-----------
And I have an offer of a replacement wall-wart and PCB coming from a very
kind list member. Not an exact match PCB, which could lead to more fun
still, but we'll see.
- Mark
I was hunting around at work today for manuals for the Lynwood Alpha
that I grabbed at the weekend. I was told to grab a torch and led to a
group of six sea containers out the back of our building. It appears
that we never really throw anything away -- it just gets put into sea
containers. I half expected to find some ex-colleagues preserved in
aspic. "Oh, John? No, he never _really_ left. No one ever does".
Presumably at some point in the future we're intending to load the
containers on board a cargo ship and dump our archives in mid Atlantic.
Anyway, these sea containers contain a treasure trove of old equipment
and manuals. It appears that we used to be into Texas Instruments 990
computers in a big way -- we've still got a bunch of manuals in the
library, but it's a tiny fraction of the files stuffed away outside.
I've a feeling the 990(s) have long since been scrapped, but everything
else is in storage. I found what I thought was a calculator like my
first school one, with red LEDs (a TI-30?), but it was actually a mini
terminal, called a TM 990/301 (I think).
Sadly, no sign of a manual for the Lynwood Alpha, but compensation came
in the shape of operator's and user's manuals for the LSI ADM 3A, ADM 11
and manuals for the Digital Engineering Incorporated Retrographics card
for the ADM 3A. Unfortunately, none of the LSI manuals answer the
age-old question of what "ADM" stands for.
It appears that circumstances are conspiring to make my web site no
longer exclusively devoted to DEC terminals. If anyone wants a manual
for the Data General Dasher D410 I mentioned yesterday, the PDF and TIFF
are online at http://vt100.net/dg/. The User Manual for the LSI ADM 3A
is online at http://vt100.net/lsi/ (proper pages to come later, blah,
blah).
Time to don a hard hat and dig deeper...
- Paul
> -----Original Message-----
> From: pete(a)dunnington.u-net.com [mailto:pete@dunnington.u-net.com]
> On Jan 21, 11:44, Adrian Graham wrote:
> > > -----Original Message-----
> > > From: David.Neal(a)ubsw.com [mailto:David.Neal@ubsw.com]
> > > you're probably looking at TK tape. Versions varied, long
> production
> > > run, but the most usual was a 5.5, usually rev 2 or better.
> > ISTR No VMS distro was available on floppy, the only VMS
> floppies I can
> > remember were boot disks for MicroVMS round V4.x.
> I have (parts of) 5.2 on floppy. It's a big box, but I don't
> think it will
> help anyone, though, as (a) it's incomplete, and (b) they're proper
> floppies, ie 8", not modern miniature imitations :-)
Given a VMS machine with a floppy drive, though, you could put standalone backup, and the distribution stuff onto floppies with little problem. That pre-supposes somebody with a working VMS install who can write the floppies you need.
I have a roommate who's got the VAXStation 3100 with the 3.5" floppy drive, and I think they're relatively common, though all the ones I have are without... so it's do-able.
It would be much easier, though, for all concerned if you can plug something else into the VAX. A CD (provided it will do 512 byte blocks) is acceptable, as is a TK50, DDS-1, etc.
You may have to find a strange scsi cable for the thing to use external SCSI devices. It's a 68-pin "honda" connector, but it's not wide SCSI, and normal wide SCSI connectors don't work. Expect to pay ~30 dollars US for the cable unless you get lucky.
Regards,
Chris
Christopher Smith, Perl Developer
Amdocs - Champaign, IL
/usr/bin/perl -e '
print((~"\x95\xc4\xe3"^"Just Another Perl Hacker.")."\x08!\n");
'
On Jan 21, 12:17, David C. Jenner wrote:
> I have an ASUS ISA-486SI motherboard, Copyright 1992.
> I have the manual for it. The manual does NOT describe
> any sort of BIOS upgrade, such as reflashing it, like later
> boards in my collection do.
I've not seen any 486 of that era with flash. More likely a PROM.
> The BIOS is not
> Y2K compliant. It appears to work OK when I set the
> current date/time, and when I turn it OFF/ON, it retains
> the current date >2000 without problem.
Is that a typo? If you can set dates after 1999 and it retains them, and
gets leap years correct, what's the problem? My 1993 Phoenix BIOS (EPROM,
not flash) is fine, for example.
--
Pete Peter Turnbull
Network Manager
University of York
Your first stop should be my web site.
http://www.aracnet.com/~healyzh/pdp10emu.html
It has links to everything you need.
For DEC emulation in general see:
http://www.aracnet.com/~healyzh/decemu.html
Zane
>
> This PDP10 simulator that is ;)
>
> I'm hacking on the simh ( http://simh.trailing-edge.com/ ) and have
> the pdp10 module compiled and running a-ok. Also looking at the
> PDP10 Software kit ( http://old-pdp-10.trailing-edge.com/ ) but I'm
> rather clueless where to even begin. Everything in the TOPS-10
> table are *.tap tapes, one is tagged "BOOTABLE". I d/l that, attach
> it to TU0 and boot TU0. Nothing happens but when I stop the sim
> it reports: Simulation stopped, PC: 000000 (000000000011)
>
> Another one marked TOPS-10 7.03 KS Bootable tape I just tried,
> with similar results.
>
> Any hints on where to start exploring or should I just give this up
> as hopelessly impossible w/o a wall of orange books and years
> of experience??
>
> Thanks
>
> Chuck
> cswiger(a)widomaker.com
>
