Console Printer looks very good and the enhanced functionality of the SAC Interface box is working well

MISCELLANEOUS WORK

My wife is decorating a fundraiser for a local foundation, an Italy-themed outdoor event, and has built roman columns, venetian mooring poles and many other items, but turned to me to help build a gondola in which arriving guests will pose for pictures. My son-in-law will be dressed in an authentic costume as a gondolier, with his pole at the ready. Blue tule will make the water underneath.

The gondola will be 16 foot long, with a 3 foot wide bench for guests, and the ends will stand about 4.5 feet tall. Mostly made with 1/4" plywood, the bench out of pine, and various pine sticks to reinforce the sides and bow them out to a pleasing angle. Will be painted black, with silver ends and various decorative touches along the edges.

It may be too darned hot to subject the 1130 to power, but clearly not too hot to be sawing, gluing, drilling, screwing, and so forth out in the sunny backyard. I was cooked by dinnertime.

1053 CONSOLE PRINTER RESTORATION

While I had the 1130 powered up, I did some testing of the tab, space and return buttons, which did seem to be working pretty reliably. I still need to run diagnostics to be sure that the 1053 is solid, but it is getting too hot right now to subject the 1130 to any more power-on time. I will continue in the evening when it has cooled down.

I fiddled around with the overly delicate and unreliable wiring on SAC Interface Box driver board, until bit 12 was working properly. I loaded and verified the diagnostic for the keyboard and console printer, then began running it to test out the 1053.

Things looked very good - using the keyboard to printer test I was able to verify that space, backspace, and tab worked properly. When it attempted a carrier return, the stiff pivot arm did the expected and left the mechanism hung up so that it wouldn't type any more. Letters look very good and the operation is pretty solid as far as I got it.

I had to power cycle the machine to overcome the hung up state of the adapter, then decided to reload the diagnostics into memory so that there was no residual state in the software that might cause problems. Alas, while I was doing this, I decided to clean up the area and put away a VOM. Unfortunately, one of leads brushed every so lightly across some cabling in the SAC box, which caused bit 12 of the incoming data to again go missing.

I couldn't do any more testing, at least until I find and fix the problem wire for bit 12. However, I was very, very encouraged by what I saw so far. I want to run through the entire diagnostic suite and check off everything on the console printer. I will turn my attention to wiring up the three 1130 control panel buttons to the relay board so that my software can cause a virtual Program Load operation, which burns up some time until the new connectors come (see below) and I can be done with these frustrating connectivity problems.

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

My test of the enhanced functionality, providing control over interrupt levels 0 and 1, worked perfectly! I can trigger and observe both interrupts at will. That proves my daughter card and the DC-DC power converter are working as intended.

I wired in the trigger for the virtual Prog Load as that is the next function to test, watching the relays trigger, before I make the change to wire the relay board in to the 1131 button circuits. This too worked perfectly, the PC program commanded the sequence and I watched the relay board cycle through exactly once any time it was requested.

There is the remaining problem from yesterday that somehow the Interrupt Level 4 request is hot - that needed to be traced down and fixed before I continued testing. I remain deeply unhappy about the connection method for the twisted pair ribbon cable to my driver card inside the SAC interface box.

Currently, I have header pins on the board and attempted to solder the multistrand wires from the ribbon cable to each pin. This doesn't work well - I end up with stray wisps, connections that seem soldered by which will rotate and make intermittent contact. Sometimes adjacent wires touch.

I need a much more reliable connection method, consistent with the existing board which alternates input and output pins on the DIP chips. I choose a 2 x 8 IDC header to fit on the board and solder down, with a ribbon cable connector. I can fan out the ribbon cable wires I want and solder them to the existing ribbon cable wires, this gives me the alternation and spacing I need. These are on order and should arrive by the tail end of the week.

I looked carefully but didn't see any loose or shorted wires on the output board that would account for the undesired trigger of Interrupt Level 4. Putting on a voltmeter showed me that the output from the fpga to the chip input was invalid. It was sitting at 1.5V but should have been either near 0 or 3.3V.

That seems like a voltage divider, which might occur if two signals were shorted, one at 3.3 and one at 0, but I don't see any spot that is shorting. Similarly, this can be the result of the fpga circuit entering a metastable state, neither 0 nor 1.

I lifted the line from the chip and measured it - it still went to 1.5V which means either a problem on the fpga board, a problem in the connector or a problem in the ribbon cable. I pulled the ribbon cable off the fpga board and inserted a single pin into C12, the port where I am seeing this problem. The result was a nice low signal at level 0, as it should be.

I did some continuity testing between that wire and adjacent wires, but no shorts or measurable resistance. No short to ground. It is odd, because it is acting like an undriven pin yet I can see the source being set in my VHDL and the constraints file seems correct for the pin as well. This is odd because this used to work until I made the latest round of changes.

I did have some completely unrelated pins hooked to an Arduino from when I was testing the medium speed link, with no power applied to the Arduino but its ground was not tied to the SAC box. I removed the four wires to the Arduino and my problem with Int Req Lvl 4 went away! However, in all the moving of the board to check for problems with the request line, I managed to jostle the line for bit 12 so that it was no longer working. Grrrrr. The new connectors can't come soon enough - this unreliability of the lines is really wasting time. 

Interrupt enhancement to SAC box wired and ready for testing, attempting 1053 pivot screw replacement

1053 CONSOLE PRINTER RESTORATION

I carefully measured the shoulder bolt that I needed to replace for the pivot arm. It has a 1/4" diameter shoulder, 3/64" deep, with the remainder of it a 1/4" long 6-32 thread. The cap is a hex 3/8" diameter, 1/8" deep. I have some leeway in the size/shape of the cap and of the length of the threaded portion, as long as the shoulder is 1/4" and at least 3/64". I can shim a deeper shoulder with washers.

Sloppy, quick sketch of the shoulder bolt that must be replaced

I found I had a nylon spacer that was 1/4" wide, but a bit too narrow for a 6-32 bolt. By the time I drilled it out, cut it down to about 3/64" wide and put it on the bolt, it had expanded just enough to make a friction bit with the pivot. While I was able to install it this way, the pivot arm needs to be pulled in one direction by a spring, which is way too light a pull to handle the friction as the pivot sits.

Back to the hunt for a good pivot surface. Perhaps I can use 1/4" OD metal tubing, which I ordered and should receive by Wednesday night. Its inner diameter is wider than ideal for 6-32. I need about .14" inner diameter but the tubing will be .20". I will use some soft rubber inside to help center the tube over the screw, which should be good enough for the purposes of the pivot mechanism. It will be challenging to cut this in a short segment - thus I likely will have to use several washers to reduce the open width to 3/64".

I believe I can replace the attachment hook onto the end of the nylon tape that shifts ribbon colors, if I loop the tape through the attachment piece and then glue the tape to itself. I am going to try E6000 glue which appears to make a good strong but not brittle joint between nylon pieces.

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

I am pondering how to make the button connections inside the 1131. The wires are soldered to the switches under the buttons, wrapped in a bundle and exit somewhere where they are fastened to a resistor block. That would be the ideal place to intercept the connections, rather than cutting wires in the bundle, but I had to first locate the illusive resistor block.

My FE Maintenance Manual has a locator chapter and with that, I found the resistor panel is down inside the chassis on the underside of the keyboard well, behind the logic gates. I have a great place to snake the wires up to the relay, a large round hole in the base plate of the keyboard well just where I intend to mount my boards.

Resistor panel where button wiring can be modified

Getting access to the panel to do the wiring will be a challenge, given the limited room behind the 1131 in my workshop. To make room, I relocated the P390 system I was checking out to my datacenter shed, which gives me space and a lighter table to swing away when I need to get in behind the logic gates (e.g. where the resistor panel lurks.

Access problem to swing open logic gates

Logic gates A and B swung out so I can access resistor panel deep inside

Once I looked at the physical panel, I had a plan for a minimally invasive wiring of my relay board into this spot. I needed three pins that would fit into the panel, which I had available from when I needed these to put into the 029 keypunch modification. I would gently remove a bit of insulation and then put on a vampire tap wire to each of three wires, leaving their pins intact but shielded by heat shrink tubing that would cover both tap and pin. These tapped wires would come up to the relay board, as would four new wires with pins attached.

Pins can be pulled out and new pins added to each vertical group of three

Since my relay board is a parallel switch for one button, a series switch for a second button, and a reverser circuit for the third button, it needed those seven wires coming up from the panel plus a wire bringing the +12V that drives these switches.

I deferred the work wiring in the switches, as I will wait until I have tested the rest and see the emulation engine clicking through its relays on command from the PC. This reduces the amount of change I made to the 1130, making any diagnosis easier for now.

It was time to find the sourcing for both +12V and +6V, and ground, that would be used by my added boards. It was most convenient to take it off of the B gate (front most of the two swing out logic gates) where I had ground, +6 and +12 at screw terminals at the bottom. I made up some terminal ends to put on the three wires and routed and dressed them.

The DC-DC converter is mounted to the right side of the usage meter and wired into the +6V supply. Next was wiring the daughter, emulation engine and relay boards to the +5V output of the converter.
Too, I hooked up the +12V to the appropriate relay board contact, as this is needed to implement the Imm Stop button.

I fired up the system to see whether I could watch (and trigger) the two interrupt levels I added, but the machine came with IL4 hot - probably another of the pesky connections to my output board which are so good at working loose and causing problems. I have to get ready now for a dinner with family, so debugging will have to wait for tomorrow. 

1053 pull links done, connected SAC enhancement into 1130 backplanes

1053 CONSOLE PRINTER RESTORATION

I tackled the broken swing-arm pivot screw, looking to put together an equivalent from a longer hex head bolt, nut and a bit of hollow tube around which the swing arm pivots. The original part is a hex head screw with a stepped diameter, the part closest to the head being a smooth cylindrical section to allow rotation and then the stepped down remainder is threaded to match the nut.

The dimensions of the very short hollow tube are important. The outer diameter has to match the pivot arm to allow smooth rotation. The inner must be large enough to allow the hex head bolt through. The length has to be slightly larger than the pivot arm thickness, allowing rotation but not any cocking of the arm to the side. Finally, my bolt has to be a good length, to fit over the hollow tube, through the bracket assembly, and allow the nut to affix but not extend too far past the outer face of the nut.

I picked up a set of hardware from a local store but it was not good enough - outer diameter too small and the threaded part too wide. I will keep at it, until I find a suitable combination. Not sure how the machine will work without the pivot arm and the switch operation, but I will probably find out.

Meanwhile, I attached two more pull links, but one came off. Tedious and extra hard because there is zero visibility to the area where the link attaches, unless I disassemble my shift mechanism and lose those adjustments. I refuse to pay that pound of flesh so it goes slowly.

Finally by early evening, all five pull links are properly attached and releasing the mechanisms when the solenoid arm is activated. I will do some fine tuning of the adjustment pressure but all five are operating pretty well right now.

Fixing the pivot arm attachment and repairing the ribbon color activating tape are left, plus adjustments, testing and cover/faceplate installation. I can see the finish line from here.

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

I dressed the wiring that runs down inside the 1131 to the backplanes, soldered on push-on ends, and used heat shrink tubing where necessary. Cable ties held the lines neatly as well, allowing for movement with the full swing-out and swing-in positions of the two gate frames. All the lines are pushed onto the respective pins on the backplane.

Push on ends added to the twisted pairs

Example of one twisted pair added to the backplane

I then had to fasten the lines to the fpga in the SAC Interface Box, since they are now wired into the 1130 system. Updated logic was written to the fpga to handle those lines. My python PC side program is updated to display and set the two new interrupt levels, so that I could test my circuit and wiring.

The DC-DC converter board came in today and was wired in. A bench power supply provided the +6V for the converter, whose output was the 5V needed by the daughter card and other boards I have inside the 1131. Since that works, I will wire the converter into the +6V SLT supply lines and mount the converter board in a suitable location.

DC-DC converter in operation converting +6V to +5V

I picked a location to mount the 'emulation engine' board which activates relays in a timed sequence, the relay board that virtually pushes the three buttons, and began to wire everything into place. I have a bit of wiring to do to hook the four relays into their three button circuits, plus the power lines will be finished once I mount the DC-DC converter board somewhere.

Approximate location of the emulation engine and relay boards

If I get the DC-DC converter wired to the SLT power supply and at least the daughter card fully functional, I can do some power-on testing of the system. The Program Load function of the emulation engine and relay board can be finished and tested independently. 

Conquered springs in 1053 console, more work on SAC interface enhancement

1053 CONSOLE PRINTER RESTORATION

I continued to wrestle with the spring that unsprung, trying to get it securely over the tang of the interposer from which it popped. I do have just barely enough access for a springhook, but I am limited by my back's capacity to spend time hunched over at exactly the angle where I can see what the tool is doing.

Finally, by mid afternoon, I got the pesky spring back on the tang. It took many short outings, each time after I felt fresh and ready to tackle the spring once again. I verified that all five interposers work properly so it was time to reinstall the operational magnet assembly.

Operational magnet assembly in place but missing pivot arm on right side

By dinner time, I had the operational magnet assembly installed. However, when tightening up the pivot screws for the two arms that provide feedback thru a microswitch when an operational cycle occurs, I had the screw snap off. Of course the screw is not found in an ordinary selectric models or in the other selectric mechanism from the Dura word processor, it is unique to the IO Selectric.

Pivot arm with screw which snapped off at nut on left

I will need to check with Grainger to see if they have a compatible screw, otherwise it will have to be made on a lathe or built up out of multiple parts. Here I thought I would be running the diagnostics tonight. I had three of the five pull links already attached so it was nearly ready.

Remaining tasks for the console printer:

• Attach remaining two pull links
• Check and adjust pull links
• Check and adjust carrier return torque
• Repair nylon ribbon color tape
• Attach and adjust ribbon color tape
• Verify correct operation before adding covers
• Install tab clear/set linkage on front plate and mechanism
• Put cover over typewriter and fasten
• Place printer in its normal position on the machine

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

I installed the female connector on the IO panel at the bottom right rear of the 1130 and hooked up the cable. It was time to verify the continuity of all the lines between the SAC Interface box and my daughter card up in the 1130 near the usage meter.

Small card at top left to handle interrupt level 0 & 1 signals

Small card at top right, another view

All is good on the lines, so time to finish up the parts inside the 1130:

• Mount the daughter board to the frame
• dress the twisted pairs to their target locations on gates A and B
• trim and install push-on connectors to the twisted pairs
• install push-on connectors to 1131 backplanes
• mount emulation engine and relay boards
• trim twisted pair and attach to emulation engine
• wire relay boards to 1130 panel buttons
• connect twisted pairs into fpga in the SAC Interface Box
• set logic in fpga to make use of interrupt lines and emulation engine
• test emulation engine with bench power supply
• test SAC interface lines with bench power supply
• develop mount for DC-DC converter and prepare wires to +6V
• wire in DC-DC converter and retest all functions

As you can see, there are quite a few steps, even if each one is relatively short, this can add up to hours of work. I spent time at night documenting all the assignments, wiring and approach.

Tab interposer spring installed in 1053 printer, wiring and cabling work for SAC Interface enhancement

1053 CONSOLE PRINTER RESTORATION

I pulled out the spring that pulls the tab interposer rearward, since it was not exerting any force. Comparing it to the proper spring which is much shorter, the reason for its failure to work is obvious. I have the proper spring and have to get it attached using springhooks and other tools that I can snake through the very limited openings given me access to the interposer and the rear attachment point.

Incorrect, overly long and weak spring on left, proper one on right

I did get the new spring hooked to the tab interposer, now the challenge was to get the other end secured over the rear mounting point. Somehow, I managed to poke a springhook from the rear, then tilt the machine and and use another springhook to get the spring over the first one. With that done, I could return to the rear, pull it out and gently coax it over the rear mounting point.

That done, I tested the tab interposer which now snaps back cleanly when pulled down, which means it will work when I reattach the operational magnet assembly and all the pull links. Before I reassemble, there is another spring, the one that extends from a tang on the back of the backspace interposer and holds the backspace operational latch frontwards, out from under the operational bail.

It is only when the backspace interposer was triggered and slid rearward that it will push the backspace operational latch under the operational bail. The operational bail oscillates down and up with operational cycles, pulling down on any operational latches which are pushed under the edge of the bail when it moves. The bail pulling down on operational latches is coupled through pivots, levers and fulcrums to the various mechanisms to accomplish the movements such as space, backspace, tab, return and index.

I got the spring hooked over the backspace operational latch but now have to force it over the tang on the backspace interposer. A few tries with sets of springhooks failed, after which I took a breather from this somewhat frustrating task. When it is on, I can reattach the operational magnet assembly since I won't need the access to the interposers any more.

I managed to hook the spring on, but while I was moving the machine around to install the operational magnets, another of the damned springs between interposer tang and operational latches came loose. I packed it in for the night and will wrestle with all the springs tomorrow, then reinstall my operational magnet assembly.

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

It was a terrific battle but finally I got my enhancement cable made. I had to snake a stiff wire through, tape the twisted pairs around then end, and then pull it back through the 17 feet of heat shrink. It took a good 100 minutes to finally work the stiff wire through the tubing, since it was pushing a bendable wire not actually any pulling.

There was no way to wires pulled through the thinner (1/4") heatshrink tube which would have been a nice fit, so I had to use a 1/2" tube which would not have tightened enough to hug the five twisted pairs. I took some token ring cable and snaked it through as a stiffener and to eat up the spare space, then applied the heat gun to tighten up the cable cover.

The male plug is now attached to the cable and the other end is snaked into place inside the SAC Interface Box. I found a good spot to connect the female connector on the 1130, near where the other SAC cables are connected. Once I build the small daughter boards that will sit near the 1130 logic gates and interface the signals to my cable, I can make up the wiring to run inside the 1130 cabinet.

I settled on the design for the small card to be mounted inside the 1131 near the logic gates and began wiring it up (with an IC socket as I don't have the chip yet). Still a few details to work out, such as the mounting location and hardware.

I ordered a small board for the power supply which will be TTL level (+5V), whereas the 1130 uses +6, -6 and +3V supplies. The DC-DC converter board will tap onto the +6V supply of the 1130 and produce +5V for any and all circuitry I place inside the 1131. Initially, it will provide power for my emulation engine (implements a virtual Prog Load button) and for the daughter card for the interrupt levels.

DC - DC power supply to cover SLT +6V supply to +5V for my TTL logic

I documented the pin assignments on the connector for the SAC Interface enhancement cable, so that I can wire up the 1130 side female connector and begin hooking the SAC Box wiring into the fpga. As soon as I have the console typewriter out of the way, I will open up the keyboard and upper cover of the 1131, to begin locating and attaching my boards and cables for the SAC enhancement.

I will secure the daughter board under the top cover, to the right of the console printer but still left of the usage meter and CE key. With the location set, I ran the twisted pairs that carry the interrupt level signals up to the daughter card from the IO connector panel at the bottom rear, having first housed the twisted pairs in the 1/4" heat shrink tubing.

Tomorrow, I will install the emulation engine and its relay board under the keyboard and switches panel, which will have its own run of twisted wire from the IO connector panel. With the wires in place, I will crimp all the female pins to the wires and install them in the female connector housing. That will get fastened with screws and nuts into an empty space on the IO connector panel. 

Light day, some work on SAC expansion cable

1401 RESTORATION AT CHM

On top of a heavy work day, I went over to the CHM in the late afternoon to help out with a few problems. There is a problem related to a broken wire inside the cable from the German 1401 to its first 729 tape drive, but a few other members were working on that. I sat down with another team member and looked at a power supply which was tripping out on the Connecticut machine, keeping it from coming up.

Ron had first checked the electrolytic filter capacitors, five 11000 uf units in parallel across the raw supply, and found that they had essentially no capacitance at all. Temporarily, he hooked up a 33000 uf electrolytic, but this is temporary until we can get the proper replacements for the five units that were in the power supply.

However, with the filter capacitors, it still wouldn't adjust to the proper -12V output level. It was sitting at a lower level, which was causing the crowbar protective circuit to trip the breaker as a protective measure. After a bit of hunting, we found that one of the ten parallel power transistors was shorted, which effectively bypassed all voltage regulation.

We replaced the transistor with a spare and then tested the unit. It needs a reference voltage of -6V for the voltage regulator card, which we supplied from a workbench supply, then verified that we could adjust the output voltage to exactly -12V.

Next, we pulled out a load fixture we have, which allowed up to place huge high power resistors across the supply and set up the unit to 0.75 ohm resistance and drive the supply up to 16 or so amps. The supply stayed at -12V, with a variance of only about 30 millivolts from zero to full load. This is ready to be put back in the system on Monday.

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

I picked up the heat shrink tubing and some connectors to use with my new SAC Interface expansion cable that adds interrupt levels 0 and 1 to the box, plus an emulated Prog Load button. I went out to snake my twisted pairs through the 17 feet of heat shrink, which was much harder than I expected.

I chose an Amphenol connector that can support up to 14 pins, twist-lock, which I will put on the 1130 end of my expansion cable. The cable will be hard wired into the SAC Interface Box on its other end. I have to designate the signals for each position, solder on the wires, and insert the pins in order to complete the cable. 

Diving into the console printer inability to trigger tab by program command, plus work on SAC interface box enhancement

1053 CONSOLE PRINTER RESTORATION

I now suspect that the tab interposer spring which should be pulling it strongly back to activate a cycle is an incorrect type. It is far too weak and thus the interposer won't slide back when pulled down by the pull link from the operational magnet.

There is also an adjustment screw which is the pivot for the interposer. On the tab interposer, this screw is much higher than the other four interposers. This may be contributing to the problem. Unfortunately, the direct way to get to these adjustments will involve removing the operational magnet assembly, a major pain.

Operational Magnet assembly removed, pull link clevises are black

Access to underside of interposers with op magnet removed

I bit the bullet and removed it. I did verify that a weak spring is the root problem and detached one end of the spring, but the far end is buried.

Correct interposer springs shown, under tension

Tab spring with almost zero tension to pull interposer rear-ward

I do hope that I don't also have to remove the mainspring, forward and reverse nylon cords, various mechanisms and starter capacitor so that I can also get to the rear of these mechanisms. That would be another huge PITA. I will hope I can do the equivalent of arthroscopic surgery with all this in the way.

Mainspring to right, other stuff blocking rear mount of tab interposer spring

SAC INTERFACE FOR ADDING PERIPHERALS TO THE 1130

I worked on my reset and startup logic for the emulation engine - the circuit that will fire off the four relays to "push" the Imm Stop, Reset and Prog Start buttons. NB - Prog Start is a DPDT switch and thus needs a pair of my SPDT relays.

Relays to push the three buttons on the 1130 console

Once I cleaned up the circuit with good noise filtering, it was working just as I wished. I wired up the relay board and was happy with the speed of the button pushing and the duration - I might not need to lengthen this beyond the 0.1s clock pulses.

Emulation engine that drives the relays with fixed timing

Here is a quick video of it sequencing, the tiny LEDs on the relay panel light as each of the buttons is "pushed". Once I work out the mounting method to install these two boards under the keyboard panel, I will wire in the switches to the relays.

I bought twisted pair cables, very similar to those used in the I/O cables on the 1130, in order to make up the supplemental cable for my SAC Interface Box. This cable will carry five signals, two inbound and three outbound. The signals involved are:

• Inbound state of Interrupt Level 0
• Inbound state of Interrupt Level 1
• Outbound request to trigger Interrupt Level 0
• Outbound request to trigger Interrupt Level 1
• Outbound request to trigger emulation engine

I cut the twisted pairs to length and am now waiting for heat shrink tubing to arrive so I can turn this into a proper cable rather than several loose twisted pairs. It is the same length as the main SAC cable, plus 3 feet for runs inside the 1131. I haven't chosen a connector mechanism yet.