1053 CONSOLE PRINTER ROTATE AND TILT TAPES INSTALLED
The machine being restored had a broken rotate tape when it arrived. Fortunately I have spare parts in the correct size for both that and the tilt tape. These are very frequently broken when someone hand rotates the type ball in a machine that is gummed up, snapping the metal tape. It can even happen in a properly lubricated machine, although the mainsprings inside tend to wind the tape up or let it out safely.
Since the carrier slides along shifts from left to right, moving the typeball to the column where a character can be printed, IBM needed a clever mechanism to move parts inside the carrier to make the ball tilt and rotate. They designed thin metal tape ribbons that attach to both sides of the carrier, with the tape passing over pulleys on each side of the typewriter frame.
Thus a tape runs from the right side of the carrier to the right pulley, returns underneath the carrier to the left side pulley, rotates over that pulley and is threaded from the left side of the carrier into a component that moves the ball. A lever attached to the left pulley will move it left or right an amount that pulls on or releases the component in the carrier to tilt or rotate.
When a character to print is selected, the mechanism inside the bottom of the typewriter frame will set up the amount of lever movement corresponding to how much tilt or rotate this tape should apply. During a print cycle the lever is moved to its desired position, the type element assumes its tilt and rotate, then the ball is locked in place and forced forward against the ribbon and paper.
The tilt tape only has the left side lever to move the carrier component to one of four tilt levels based on the T1 and T2 bits of the print command. The rotate tape has an additional lever on the right in addition to the left lever that selects one of eleven rotation positions based on the R1, R2, R2A and R5 bits. The right side lever pulls hard enough to spin the ball an entire 180 degrees, exposing the other hemisphere. This is how the upper and lower case is implemented on the typewriter, by moving the right lever out or in.
The rotate mechanism is a wheel at the bottom of the shaft connected to the type element (ball). It has a mainspring inside to preload it allowing for a quick rotation as tape is loosened. Tightening the tape by moving the levers out will of course spin the wheel one way, but when the levers move inward releasing tension the spring causes the wheel to snap around in the opposite direction just as fast.
A slot in that wheel accepts the anchor tab on the rotate tape and the tape is wound around the wheel in a channel keeping it securely in place. This slot is down inside the carrier and under the upper nylon wheel that implements tilt movements, so hard to see or get to.
Tilt is implemented by a nylon rotary cam on the which rotates around the type element shaft independently of the shaft rotation from the other tape. As this upper partial wheel rotates it moves levers that lift the typeball up or down to one of four positions. A strong spring will pull the ball to the home tilt position and the levering of the tilt tape pulley outward is what moves the tilt mechanism to the other three tilt positions.
On the right end of the carrier is a hole with a screw threaded vertically through its opening. The tilt and rotate tapes have circular fittings on the end which are placed in this hole and through which the screw is threaded. This anchors the other end of each tape to the carrier.
it is tedious work to get the rotate tape T shaped end in the slot on the wheel, less so to fit the tilt tape round end in the more accessible nylon tilt wheel. but threaded the new tapes onto the machine, around the pulleys and properly tensioned.
COLOR SHIFT RIBBON STILL REQUIRED
There is a third tape in this printer which is not found in most Selectric typewriters. There is an option to have dual color ribbons for printing, where the length of the ribbon is divided in half vertically with one color on the top half and another color on the bottom half. This is almost always red and black. Just like the tilt and rotate mechanisms, a tape running over pulleys is necessary to have the fixed mechanisms on the typewriter body cause a movement of some part inside the carrier.
During a print shaft cycle, while the ball is tilting, rotating and ultimately hammering forward, the ribbon lift mechanism will move the ribbon up in front of the point where the character on the typeball will strike. On monocolor typewriters, a lever on the carrier sets whether this lift positions the upper, middle, or lower section of the ribbon in front of the character, plus one setting will stop the ribbon from moving between character and paper (Stencil mode).
On the dual color model, the lift mechanism will raise the ribbon to either the center of the top half or the center of the bottom half, thus printing with that color ink. Instead of a metal tape, this part of the machine uses a clear plastic tape that is attached to the carrier and runs over pulleys to a mechanism that will pull on the tape or release it to cause the lift mechanism inside the carrier to move correspondingly.
This attaches to a fixed point near the front right side of the carrier, is routed to the right and around a fixed position pulley, then routes to the left side passing undeneath the carrier. On the left are a pair of pulleys, routing each side of the tape down to a final pulley controlled by two solenoids. The solenoids select which of two positions the final pulley takes, thus moves the carrier lift mechanism to its two positions.
This ribbon is truly unobtainium, I have never seen spare parts listings for this tape. The number of dual color and I/O Selectric machines in the wild is quite limited and they are not available as parts donor machines. Thus I have to create one myself.
I will need two attachment end, basically small rings that fit over an attachment point on the carrier. I will need to make a plastic tape of the correct strength, width and length. Finally, the attachment ends must be put on the tape. I believe this will be done by folding the end of the tape through the hole in the ring and using the proper plastic adhesive (or heat) to form a loop. This is a future task.
CALCOMP PLOTTER (IBM 1627) PEN SOLENOID OPPORTUNITY
I received a partially damaged and incomplete plotter several years ago from a friend. The cylinder on which the paper moves and the pen draws upon was dented in. In addition, it was missing its pen assembly.
On this plotter, a cylindrical structure is connected to the traveling arm that moves left and right across the width of the drum, that arm moving the pen left or right. The drum rotates to move the paper up or down under the pen. Finally the cylindrical structure has the pen mounted inside and, using a solenoid, will either lift the pen up off the paper or let a spring push it down to make marks.
Calcomp designed and manufactured this plotter under its own label as the Calcomp 565 but also allowed mainframe manufacturers to relabel it under their own logo. One use was on the Eliot computers, but the important such rebadging was IBM selling this as the 1627 plotter. It was originally sold with the IBM 1620 computer, but carried forward and offered on the IBM 1130 as well.
The pen solenoid (and the inserts for ballpoint and fillable ink pens) were kept in a separate wooden box near the plotter and generally attached only when the plotter was going to be used. As a result many of the plotters became separated from their pens and solenoid as they were taken out of service. The box and its contents didn't look like a computer part which meant the box was far more likely to be trashed and lost forever than the plotter.
Thus many plotters in private or museum hands do not have their solenoid and pens. No plot can be made as a result and they sit as shelf queens on exhibit. Finding a box for sale is extraordinarily unlikely and uncommon, particularly with multiple plotter owners chasing this elusive part.
The pen assembly is a cylindrical body with two contact pins near the bottom. It is inserted into the plotter arm which supplies electrical connections to the pins. Inside the assembly is a solenoid coil that will attract a metal slug when it is powered. This slug moves upward when the solenoid is activated. The slug is hollow and the inner channel holds the pen that will do the drawing.
A spring in the cap at the top of the pen assembly pushes the pen and the slug downward so that it is in contact with the paper on the drum. When activated the solenoid pulls the pen up off the paper, thus allowing movement of the pen to a new position with drawing. The programmer turns the solenoid on and off to set the pen on or above the paper.
There were a variety of pen inserts that fit into the slug, ranging from different colored ball point types to fluid filled fountain pen types. For my purposes I would be happy with just a single working pen and of course the entire solenoid assembly that goes with it. I have waited for years to find such an assembly.
A few days ago I spotted, on eBay, a Calcomp part for sale called a cutter assembly. It didn't mention the model 565 but visually it had an almost identical pen assembly. I looked at the pictures carefully. There were no online mentions of this kit nor documents I could read, but I took a gamble and bought it.
Instead of a pen insert inside the slug, this has inserts with diamond tips, very fine, which will slice foil under control of the plotter. The top cap is different from the pen assembly, as it rotates to four fixed positions that match the direction of slicing of the cutting tips. One turns the cap to the direction that cutting will occur, uses the plotter moving only in that axis, and changes it again to cut along the other axis.
I verified that the solenoid and slug part is the same. It reacted properly to current to move the cutter tip up or let it drop. I fits exactly into the moving arm of the Calcomp 565/IBM 1627 plotter.
My task now is to make pens to fit inside the slut instead of the cutter tips. I could either stick with the existing cap, ignoring the rotation as the pen does not need to be aligned to the direction of motion, or I can have a cap manufactured to be identical to the Calcomp part. I suspect that I will be able to cut down and seal a ballpoint pen insert and fit it in a sleeve that in turn sits inside the slug. Doing the pen work is a future project since the 1130 restoration is the highest priority right now
To make my plotter fully functional requires the drum to be repaired/replaced. Because it is made from soft aluminum, when it was forced back to its cylindrical shape, the areas that had been bent the most were stretched (a very malleable metal) and thus it seems highly unlikely I can restore it to a cylinder whose deviations from perfect radius are small enough to not snag the pen or distort plots.
The drum has pins on each side to accept pin feed paper. These have a conical shape and are riveted to the drop with a spacing that matches available pin feed paper. I have not found a source for the pin feed rivets so that even if I manufacture a drum the correct shape and dimensions getting it to have the pins will be an extra challenge. This is a task for the future, not for now.
DOCUMATION M600 MAG SENSOR REPLACEMENT
I have two Documation punched card readers, an M1000 and M600 which read at 1000 and 600 cards per minute respectively. The M1000 is used as my card archiving system, letting me read decks and capture the data into files. The M600 could be made into a reader attaching to an IBM 1130, through some conversion circuitry that would make it appear as a 2501 card reader to the CPU. If not, I can sell this to someone looking to do card archiving.
The card reader uses air blowers and vacuum to separate the cards in the hopper, grabbing only one by suction and pushing it into the rollers where it will move through the machine. This is very tolerant of swollen cards or roughened edges that would be impossible to feed through an IBM card reader which uses a machined throat and moving knives to force each card into the machine.
As a card is moved through various rollers from the input hopper to the output stacker, it passed in front of a set of twelve vertically mounted photocells that are aligned for the 12 rows of a standard punched card. These will read the holes to grab the data but the machine needs to know when it is at each of the eighty column positions of the card.
This is accomplished by a fine toothed wheel that rotates along with the card movement. A magnetic sensor detects the pulse as each tooth moves by and this will drive various counters to determine the position of the card. As the light is first blocked by the leading edge of the incoming card, the timers start. Driven by the sensor pulses, it counts until the solar cells are positioned in the middle of card column one. This is based on the number of sensed teeth per inch of card travel.
My M600 reader began to be flaky and then failed completely. The symptom was that the reader fed three cards into the stacker and reported a Pick error. To handle misfeeds, the mechanism tries three times to pick a card, each time watching to see the light of the photocells blocked by the incoming card. If this does not occur, it decides that cards are not feeding and raises the Pick error.
Without the timing pulses, the circuits that would see the leading edge pass were not activated, thus the correctly fed cards just passed through the machine without detection. I discovered this was caused by the lack of timing pulses and checked the sensor. Initially, it resumed working after I did a bit of probing around but eventually it failed again.
The issue was a continuity break. I had hoped it was a break in the cable from the sensor up to the reader electronics, but I found that it was deep inside the sensor itself. Even after chopping and cutting away the plastic I could not get close enough to find and repair a break. The spare parts are no longer available, of course. Further, there are not full specs for the impedance, pulse strength. and pole pattern that would be helpful to find an exact substitute. I could measure the diameter and other physical specs.
I decided to try a sensor used to drive tachometers in vehicles, because it was at least mechanically compatible with the original sensor. I mounted it in the reader and soldered it to the electronics cage connector. The pole gap from the teeth of the wheel was set to the original sensor spec.
There may be problems if the sensor has an impedance quite different from the original one, requring me to change some components in the reader electronics to match properly. I could also have problems if the signal is too strong or too weak with the pole close enough to detect one and only one tooth at a time. These are solvable with some additional circuitry such as amplifiers or attentuators.
When I next get time I will finish adjusting the reader to pass cards and look at how this sensor works in the machine. Hopefully I can get it to read cards. The sensor drives a Schmidt Trigger circuit thus it shouldn't be extremely sensitive to shape of the incoming signal. We just need the pulse to be high enough to flip the trigger circuit then the rest state be low enough to flip it back, with the duration of the generated pulse long enough to trigger the counting circuits.
UTRACER TUBE TRACER HEATER CONTROL DEBUGGING AND IMPROVEMENT
Testing vacuum tubes can be done to compare them to the characteristic curves provided by the tube manufacturer. This provides far more information that a simple conductance meter or a good/bad light that are typically found on tube testers. This is more akin to transistor curve tracers and can spot faults that are not apparent with the simple testers.
uTracer is a tool developed by a Phillips Electronic research scientist, Ronald Dekker and sold as a kit, I built one of these and mounted it inside an old traditional tube tester. It communicates over USB to a PC running a graphical user interface that controls the testing and displays the various curves.
I discovered a modification designed by Stephan Lafferty to provide better heater (filament) power, which I also built. The uTracer has some weaknesses in accurately driving the filament voltages for the tubes, which this precision heater supply eliminates.
After I finished assembling the heater board my first tests showed it was not working. The design leverages a buck regulator board from China and I was not getting output from that board. I tried a couple of other boards but had the same results. Stereo microscope examination of my build showed that all the solder joints are correct, no shorts and everything seemed okay. At that point I had put it aside.
The buck regulator has its feedback pin controlled by Stefan's heater board logic rather than the circuit built into that regulator board. The design by Stefan has the builder remove a resistor to disable the on board feedback and tack a wire to the control chip feedback pin to receive signals from his logic.
Stefan specified a regulator using the XL4005 chip to convert with a 300KHz PWM frequency and source up to 5A current to the filaments. Back when I built the heater board, eBay only had XL4015 based buck regulators. I couldn't find any based on the XL4005. Both types of boards supported 5A current and seemed very similar so I proceeded to use the board with the newer chip.
I realized when I picked up the heater board project bin during an idle moment that I should look deeper at the two types of control chips. Two key differences exist between XL4005 and XL4015. The latter chip operates at a slower 180KHz which by itself might be tolerable, but its feedback pin voltage set point is 1.25V instead of the 0.8V for the pin of the XL4005 chip. Thus the heater logic to control the regulator was producing the wrong voltage level causing the buck converter to fail to deliver the heater power.
This time when I searched online I found XL4005 based regulators, looking just like the original board from Stefan's design. I ordered it and am expecting it in soon. Again, not a high priority project but when it arrives, if the heater board works, then I will build a better front panel and finish up my tracer.
CHECKING OUT MY IBM INPUT OUTPUT TOOL
IBM repair engineers (CEs) had a tool that would provide additional lights for status display and switches to control some peripherals offline without tying up the computer to which they were normally attached. Thus IBM did not have to equip each peripheral shipped with the additional monitoring and testing panel instead temporarily attaching this tool that might be shared across many customer installations.
This box attached to connectors inside the peripherals it supported. Among others, it was used with the 1050 console of the 360/30, the 2501, 2520, 1442, 1443, 1016, 2671, 2701, and the devices supported by the 2821 controller including 1403 printers and 2540 card readers. It typically sat on top of one of the mainframe or controller boxes, with a small hook to attach to the top vent grill.
Overlay sheets were provided for each device it supported. They slid in front of the bank of 90 lights, arranged into 15 columns and 6 rows. Thus the meaning of a particular light depended on the peripheral it was wired to, even though that light is always wired to a specific pin of the connectors on this tool.
The tool also provides 7 momentary and 21 two position toggle switches plus a five position rotary switch. A cue card sits below the switches to indicate their use for each peripheral.
The tool is powered in one of two ways, depending upon the peripheral to which it attaches. If fed 24V AC, its internal power supply creates the voltages needed for the lamp drivers and lamps. Otherwise, the peripheral feeds in +3V DC and +12V DC and the internal power supply is not used. I tested this both ways to be sure that it works properly.
My testing involved using Lamp Test to verify that all bulbs lit up. Quite a few did not. As I moved them around I found that only about half the bulbs I had were working. However, they worked properly when moved to any of the 90 positions. I also tested the connector pins to light the lamps, verifying that 3V on that pin would cause its associated light to glow.
The switches are simply bare contacts brought out on the connectors to the peripherals. No debouncers or other electronics attached to them. Many of the switches shared the same common pin for the armature, but had unique normally-open and normally-closed pins assigned. I validated all the switches.
Initially I found the Reset switch was bad but was able to repair it with an appliation of Deoxit.
I truly don't know what I will do with this. It could be handy to wire to various signals of an 1130 or peripheral under test, but not very essential at all. I may just sell this to another collector.
