
Repairing the card reader for a 1960s mainframe: cams, relays and a clutch - zdw
http://www.righto.com/2018/02/repairing-card-reader-for-1960s.html
======
jacquesm
Heh, that very much reminds me of fixing an industrial sewing machine. This
machine was made by Naumann, an East German absolutely rock solid piece of
engineering.

The mystery was that one day to another it stared eating needles, and in some
cases spat out the broken pieces at high velocity in all directions.

The good news is that you can spin a sewing machine very slowly by hand to see
what's going on and while doing so I saw that - obviously - the needle was
going down into the spool chamber at precisely the wrong moment, with the
spool chamber still being closed. It's a very intricate mechanism that passes
the needle thread _under_ the spool using some black magic to pretend the
mechanism comes apart while it does the move. Timing is super precise.

Like in the card reader example the origin of the problem was a part that had
slipped on shaft. Apparently a bunch of thread had gotten stuck solid enough
that it had wedged one of the cams hard enough that the shaft inside it had
continued to move.

Even after finding the cause it still took forever to figure out the right
setting (no markings on the shaft, no service manual for that particular
machine indicating the right angle) but eventually I got it working and it
still works today.

I love those old fashioned pieces of machinery, if a modern day appliance
would break there is a good chance you would not be able to do anything about
it, but this old stuff just takes some patience and basic observation skills
and you can keep it going.

~~~
jalayir
The prices of modern appliances have come down due to really intricate
miniaturization of many components, which enables larger scale manufacturing
and cheaper supply chains.

Because of the prices being low, it's not really worth it to repair consumer
goods anymore. And if it's worth it in some cases (iPhone), it can only be
done by a specialist due to the extreme miniaturization.

~~~
perl4ever
I've discovered that modern appliances _are_ repairable, thanks to the
internet. There are people that have been making a business based on supplying
parts (for example for made-in-China GE dishwashers) and videos on how to
install them.

I think it's more accurate to say that first world labor costs are such that
it's not usually worth it to pay someone to fix your devices these days, but
it's becoming easier to DIY.

I also fixed an old laptop based on mail order parts and a youtube video. It
really gave me a sense of accomplishment because I turned to programming
computers very young partly out of ineptness with mechanical devices.

~~~
jandrese
Yeah, the Internet is a godsend to people who repair their own appliances. For
the most part you just have to figure out what's wrong (most appliances are
pretty simple, so this isn't very hard), then look at the part for a model
number and punch it into Google. Failing that you can enter the model number
of the appliance and often get a parts list. The part you get usually won't be
an exact match, but it should work, although you may have to fabricobble a
bracket if the new part isn't the same size/shape or has mounting holes in a
different location. This is pretty rare though, usually it's just bolting the
part on.

This is also when you discover that even though Frigidare may sell dozens or
hundreds of different fridge models at wildly different price points over the
years, most of them use basically the same innards.

~~~
perl4ever
The key for someone like me is a site with videos for every little part for
the exact model of appliance. And troubleshooting information, and possible
causes of a symptom ranked by customer experience %.

There have always been DIYers, but I cannot do much of anything with just a
service manual or parts list.

------
WalterBright
A long time ago, I discovered that a nearby neighbor had a beautiful Mercedes
limo from the 50's in his garage. I asked him about it, and he said he had
restored it. I asked him how he dealt with acquiring parts that were no longer
available.

He replied: "Oh, I made them."

Me: "What...."

So he showed me his full sized basement, which was a fully equipped machine
shop. He'd built working steam locomotives that were several feet long, and
other mechanical models, all working, all from scratch.

I was amazed. I asked him what the Mercedes was worth, and he replied, and I
remarked that it couldn't be worth all his labor he put into machine work. He
agreed, and said it was his hobby and evidently made him happy.

These days, of course, you can just make a drawing of what you need and send
it to one of those online machine shops.

~~~
ams6110
Mercedes-Benz "Classic Center" still has parts for all their cars, at least
the post-war cars.

Not to say that it might not be cheaper to make your own in some cases if you
already have the means and skill to do it.

~~~
sokoloff
My family restored (to good driver condition) a '59 220S (just sold); our
experience was that not every minor cosmetic or interior part was available at
Classic Center. Mechanical and functional part availability is excellent,
pricing reasonable, and the staff there is top-notch, but they don't have
everything.

------
abraae
Fantastic as always Ken. I spent years of my life repairing IBM mainframes and
I love these info drops.

I guess its part of human nature to assume that our predecessors were dumb
peasants (how did they build those pyramids?) but IBM had some incredibly
sophisticated and elegant electromechanical, pneumatic and hydraulic systems
in those days.

The worst beast I used to work on was the 3890 check sorter
[https://en.wikipedia.org/wiki/IBM_3890](https://en.wikipedia.org/wiki/IBM_3890).
This monster filled a (large) room, and when it was down, stress points went
through the roof as bank's check sorting and money clearance ground to a halt.
There's nothing like having a furious CEO leaning over your shoulder shouting
at you while you're elbow deep in a dusty noisy furiously spinning machine to
raise your blood pressure.

------
jf
> The Computer History Museum in Mountain View runs demonstrations of the IBM
> 1401 on Wednesdays and Saturdays so check it out if you're in the area; the
> demo schedule is here:
> [http://www.computerhistory.org/hours/](http://www.computerhistory.org/hours/)

Regarding the IBM 1401 (to borrow from "Ferris Bueller's Day Off") It is so
choice. If you have the means, I highly recommend seeing it in person.

I've had the pleasure of seeing several presentations and even punching cards
to be run as part of a demo program. The machine is impressive to see in
person and the volunteers who run the tours are a lot of fun to talk to!

~~~
linker3000
Agreed - if computer tech is your thing it's a __really __good place to visit.

I was roped in to one of the Babbage Engine demos a few years back...I turned
up about 10 mins early and started to talk to the presenters, who were really
nice guys. When I volunteered that I'd also seen the other replica Engine in
the Science Museum in London, the chaps were proud to point out that 'theirs'
could be operated and was not behind glass. I was then asked if they could
refer to me at a suitable point to mention those facts and give my impressions
on the presentation, which I was happy to do!

------
minikites
Icelandic musician Jóhann Jóhannsson composed an album of music created with
sounds created by the IBM 1401. This particular track also includes what seems
like an audio recording of a technician going over the machine's
specifications and some basic troubleshooting:
[https://www.youtube.com/watch?v=KPFAkBCizr8](https://www.youtube.com/watch?v=KPFAkBCizr8)

More information here:
[https://web.archive.org/web/20120307215225/http://www.ausers...](https://web.archive.org/web/20120307215225/http://www.ausersmanual.org/data/)

>In 1964, a computer - the IBM 1401 Data Processing System - arrived in
Iceland, one of the very first computers to be imported into the country. The
1401 has been called the "Model T" of the computer industry - the first
affordable, mass produced digital business computer. The chief maintenance
engineer for this machine was Jóhann Gunnarsson, my father. A keen musician,
he learned of an obscure method of making music on this computer - a purpose
for which this business machine was not at all designed. The method was
simple. The computer's memory emitted strong electromagnetic waves and by
programming the memory in a certain way and by placing a radio receiver next
to it, melodies could be coaxed out - captured by the receiver as a delicate,
melancholy sine-wave tone.

------
zw123456
When I was a grad student back in the late 70's, I worked in the campus
computer center where all the undergrads had to use Hollerith cards and only
the grad students got to use CRT terminals. There was one card reading machine
that was known to be flakey and would mis-punch the letter E occasionally and
I used to love it when they would come up to me all frustrated that their
program would not run and I would pull the offending card from their deck and
hold it up to the light and pretend like I could sight read Hollerith and tell
them they had a mis-punched card. They all thought I was a god... until
someone would clue them in not to use old reader #11.

------
Animats
That's such an IBM design. IBM mechanical designers were used to designing
systems with continuously running shafts and electromagnetic clutches, because
that's how tabulating machines worked.

Early card readers were unreasonably complicated. Then came Documation.[1]
They solved the problem of card feeding. There's a air jet system which spaces
out the cards, and a vacuum picker which pulls the bottom card off the stack
and feeds it into feed rollers. The card path is straight and simple, card
picking is not highly sensitive to card thickness, and the machine is far
simpler than the 1402. Documation soon owned the card reader business.

[1]
[https://www.youtube.com/watch?v=qu55b0GpgE8](https://www.youtube.com/watch?v=qu55b0GpgE8)

------
ivoras
It's humbling to thing that today, doing the same thing (if for some reason
we'd like to use punched cards) we'd do the same thing with a $10 camera, a
$35 Raspberry Pi and some trivial OCR-like software. Heck, even an ESP8266
could process images that simple.

~~~
maxerickson
The machine in the article does 13 cards per second. A cobbled together OCR
machine probably isn't going to match that.

~~~
kens
Exactly! Being able to reliably read 13 cards a second from a stack is quite a
feat, requiring precision components such as picker knives and jogglers moving
at high speeds. (I am not making up the joggler; it uh joggles cards into
alignment.) Optical reading would avoid the metal brushes, which get out of
alignment or make intermittent contact, but that's not the hard part.

Yesterday's "Why Paper Jams Persist" in the New Yorker is also relevant, a
look at why its difficult to move paper through a printer reliably. Punch
cards, being made of paper, have the same problems but worse - they are
weakened by the holes, and mistreated by the public. (Older readers may recall
"Do not fold, spindle or mutilate" printed on punch card utility bills and
such.)

[https://www.newyorker.com/magazine/2018/02/12/why-paper-
jams...](https://www.newyorker.com/magazine/2018/02/12/why-paper-jams-persist)

~~~
DrScump

      reliably read 13 cards a second
    

... and with considerable tolerance for bent or frayed cards.

As late as the late 80s, Lockheed used IBM cards for time cards (for everyone,
hourly or salaried). Lots of handling, lots of abuse, yet over 99% read ok on
first try. That's over 14,000 in one job (program) every week for years on
end.

------
oneplane
CuriousMarc (I think, not sure if typed correctly) has a lot of behind the
scenes videos on YouTube for that vintage computer stuff, mostly at the
Computer History Museum where they work on the IBM 1401 and the Xerox Palo
Alto.

Some of the repairs are for the tape drives, some are for the CPU itself, it's
all really interesting to see.

~~~
kens
CuriousMarc's YouTube channel is
[https://www.youtube.com/user/mverdiell](https://www.youtube.com/user/mverdiell)
and has lots of videos of the IBM 1401 as well as the Xerox Alto restoration,
HP hardware, and other interesting things.

~~~
jxramos
Cool stuff, I'm watching [The IBM 1401 compiles and runs FORTRAN
II]([https://www.youtube.com/watch?v=uFQ3sajIdaM](https://www.youtube.com/watch?v=uFQ3sajIdaM))
and seeing that alternating green and white printer paper brought back some
old memories of when dot-matrix printer paper was used as scratch paper during
school days.

Impressive to even see its still for sale
[https://www.google.com/shopping/product/13500800368299416699](https://www.google.com/shopping/product/13500800368299416699)

------
breakingcups
I love articles like these, even though I wasn't alive when these machines
became widely used they are fascinating to read about.

Unfortunately I live nowhere near a museum with a functioning mainframe, but I
would love to see one in action someday.

------
linker3000
A good write-up and read, as ever, Ken.

I've a punch card from that machine (somewhere!) - picked up the last time I
visited the museum.

I used to fly over from the UK a few times a year to visit corporate HQ in San
Jose, and I used to enjoy taking the VTA light rail to Mountain View at the
weekend and walking to the museum.

Sadly, I have now changed jobs so the chances of coming over again are very
low - unless you need to hire a 'specialist' to hold your multimeter!?

~~~
kens
We can always use a specialist multimeter assistant, but the pay is low :-)

~~~
linker3000
OK, I'm in. If pay is low, I may have to line up a side gig at somewhere
nearby - know any local business that do computer-oriented stuff!?

------
fernly
Also be sure to find the link to the schematic, which is kind of buried in a
footnote. 59 page PDF.

[http://bitsavers.org/pdf/ibm/1402/1402_Reader-
Punch_Wiring_D...](http://bitsavers.org/pdf/ibm/1402/1402_Reader-
Punch_Wiring_Diagram.pdf)

------
gtirloni
Ken was recently in the Unnamed Reverse Engineering podcast and it was very
interesting too: [http://reverseengineering.libsyn.com/005-circuits-that-go-
to...](http://reverseengineering.libsyn.com/005-circuits-that-go-to-nowhere)

------
IgorPartola
Were things like servos and stepper motors things that came after this era?
This seems... awfully mechanical for what it’s doing.

