[vcf-midatlantic] Repair Workshop Wrap-up 3/30 & 3/31

[Jeffrey Brace]

Bill and Duane,

Thanks for all your work. Please let me know if there is any way to support
you further.

On Thu, Apr 4, 2019 at 1:01 PM Bill Dromgoole via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> Univac Workshop Report
>
>
> Duane and I arrived at the museum on Tuesday afternoon.
> After getting settled at the on campus lodging, we started evaluating the
> condition of the Univac equipment.
> The 1219B computer was working as usual with a small problem in the upper
> I/O channels.
> The 1540 digital data recorder is in poor shape. Lower handler will not
> move at all.
> No communication with 1219B computer. The 1532 I/O console appears to be
> working fine.
>
> Duane built a USB to 1219B interface(MIL-STD 1397 type A) device using an
> arduino chip which he brought with him to test.
> After playing around for a while we were able to upload files from a
> laptop computer to the Univac.
> We spent most of the next day copying files to the computer and dumping
> them to the paper tape punch in the 1532 I/O console.
> We also spent time trouble shooting the 1540 DDR concurrently with the
> file copying.
>
> The first problem on the DDR turned out to be a bad logic translator card
> in the handler electronics itself.
> Fortunately we were able to find one in the spares at the warehouse.
> This corrected the signal to the pinch rollers but the tape kept jamming
> in the tape head area.
> Turned out to be a bad roll of tape with poor oxide retention.
>
> Over the next couple of days we found a lot of bad cards in the 1540 DDR
> with a lot of trips to the warehouse for parts.
> Most of the failures were intermittent and took a while to locate.
> At one time we were able to copy a program from memory to magnetic tape
> and then reload it to memory, although the handshaking was not proper.
> Things kid of went downhill from there.
> More card failures in the DDR. Not communicating with the 1219B, clocks
> not running bits in various registers always set, etc.
> We were able to find most of these and get some of the communications back.
> Meanwhile after editing some programs on the laptop and trying to punch
> new tapes the paper tape punch started to not work properly.
> Next, the keyboard on the teletype started jamming and after that the
> paper tape reader stopped working.
>
> Found that the tape reader power supply is failing. Plus and minus 15
> volts slowly drifts down to 8 to 10 volts.
> Was unable to repair before the weekend was over.
> The keyboard is probably just not lubricated properly.
> One of the new programs we copied uses the keyboard a lot.
> We hardly used it before this trip. So that highlighted this problem.
> The punch problem may be related to the reader power supply? Who knows.
> Was able to use the time left after clean up on Sunday to scan another one
> of the Univac pubs to a PDF file for bit-savers.
>
> Final status:
> Computer working fine.
> Digital data recorder is mostly working. Still needs possible alignments.
> I/O console almost completely inop except for printer.
>
>
>
> From: Jeffrey Brace via vcf-midatlantic
> Sent: Sunday, March 31, 2019 4:08 PM
> To: vcf-midatlantic
> Cc: Jeffrey Brace
> Subject: [vcf-midatlantic] Repair Workshop Wrap-up 3/30 & 3/31
>
> We had about a dozen members working on their machines and VCF machines
> Saturday and Sunday. Most did two days while some did one day.
> Bill Dromgoole and Duana Craps had worked on the Univac 1219B in the museum
> for the past week. They can give an update later as to their progress.
> David Gesswein worked on the museum's PDP-8. He will send a report later.
> There were others working on various projects.
> I got there midday and wasn't able to work on anything Saturday.
> Sunday I took VCF's turn at the InfoAge front desk.
> Evan can fill you in on what he was working on as well as the others.
>
> This time we went to a new place: MJ's for Saturday dinner. Everyone liked
> it.
> Afterwards we played Cards Against Humanity which is always a fun time.
> Sunday morning we went to a new place: Mariner's Cove for breakfast. Also
> great food!
>
> The next workshop is April 13 & 14.
>
> --
> =========================================
> Jeff Brace
> Vice President
> Vintage Computer Federation
>
> --
=========================================
Jeff Brace
Vice President
Vintage Computer Federation