Aligner board not quite right, but should get it on the next revision

 EXPERIENCE WITH THE POLY FOAM BOARD

I received my poly foam board from the laser cutting site - 1/2" thick foam with the holes cut to allow the lamp holders to sit properly aligned for a quick easy insertion into the honeycomb matrix.

Poly foam aligner mask in place

First observation was that the foam is just too soft to push the lamp holders fully. It does help with some of the tilt such that they are very nearly correct even with this material.

Second observation was that with 1/2" foam the bulbs barely stick up out of the foam. I need some of the nylon lamp holder to be proud of the board in order to slide into the honeycomb cells and ensure the light is directly into each hole. 

The brightness was adequate and this could have been made to work, but the PCB could slide up, down, left or right of its intended position because the foam surface doesn't let the holder drop into each hole. 

NEXT APPROACH

It is time to take the design file and send it back to the fab, selecting a more rigid and less thick material. I believe 3/8" would be perfect for the height, but I will do more measurements before ordering the new board.

Created design for the aligner board and sent to fab

 DESIGN DECISION REFINEMENT

My original design for the aligner board was to have truncated pyramid shaped openings that would gently bend the various lamp assemblies into alignment as it was slid down to contact the face of the PCB. However, since the aligner is placed on the PCB while it is laying upright in front of the maintainer, it did not have to accomplish the bending.

Instead, the person putting the boards together can touch and move various lamp assemblies as needed while the aligner is tilted into place, first working on one edge then tilting the aligner board increasingly parallel to the PCB as it engages more lamp assemblies. A pencil eraser or similar tool is all that would be needed to move the errant lamps into position, column by column. 

This greatly simplifies the production of the aligner board, since a simple rectangular opening is all that we need. No bevel cuts or sloped cutting/adding are required. 

CHOICE OF MANUFACTURING METHOD

Based on the relaxed design approach, I decided that laser cutting was the right choice for me. The material had to be around 1/2 " thick to provide enough alignment for the assemblies, not extremely hard but not so soft that the lamps flop over out of alignment. 

DREW UP DESIGN IN INKSCAPE

I drew the laser cutting paths using Inkscape, duplicating the board since my template was large enough to produce two copies of the part. I can send the other copy to the museum that is replicating my lamp system for use in the 1130 they are restoring. 

Laser cutting pattern

SENT TO PONOKO.COM FAB FOR LASER CUTTING

I chose one day manufacturing and overnight delivery since the total cost was very reasonable. I picked a 1/2" polyurethane foam for the material, which I hope will be stiff enough to maintain the alignment. We will see when it arrives, then at worst case change the material and send the job off again to the fab. 

Almost there! Fix one position and move two bulbs

 TRIAL INSERTION OF BULB MATRIX

With essentially every lamp holder in place, I tried to slide the PCB with lamps right into the honeycomb matrix. I still had to do a bit of wiggling and playing with holders that were skewed a bit, so this still doesn't meet my expectation for a rapid and effortless insertion, but it is much closer than any previous incarnation including the original IBM mechanism. 

Test fit of PCB with new holders behind panel

LAMP TEST VERIFICATION

Using the Lamp Test signal to turn on all the lamps, I had a chance to check that all the bulbs I installed were working properly. As you will see, two of the CE positions are dark because I was short two bulbs from having a fully populated board, but in addition the lamp for Index Register 2 is out. It doesn't light with a direct signal input either, causing me to suspect that it is an issue with the newly installed bulb in the holder assembly.

CE 4, CE 5, and IX2 are dark (for different reasons)

DOH MOMENT RELATED TO IAR AND MAR REGISTERS

If you look closely at the left side of the control panel, where the six major 16 bit registers are displayed, you will see that the leftmost (bit 0) lamps do not shine through for the top two rows. These are for the Instruction Address Register and the Memory Address Register. That is consistent with a system that can only address a maximum of 32K words, thus needs only bits 1 to 15 to contain all possible addresses. 

Since the machine does not contain signals to drive bit 0 of IAR or MAR, and the panel does not have an opening to allow the light to shine through on lamp test, there is no reason to populate those two positions. 

That gives me back two lamp assemblies, exactly what I need to fill in the missing two positions of the CE signal area of the panel. I don't need to wait for a new supply of 2114 bulbs to finish this up and install it in the IBM 1130.

WORK AHEAD

First, the two lamps from IAR bit 0 and MAR bit 0 will be moved to the CE signal area. Second, I need to check out the IX 2 circuit and lamp, repair it and retest to demonstrate all 162 lights active simultaneously.

Beyond that, I am exploring ideas for an alignment honeycomb that will slide over the lamp holder assemblies on the PCB, holding them upright at the correct position, so that the sandwich of PCB and the alignment part will slide easily into the display panel honeycomb matrix. I envision something produced with a laser cutter, material to be determined but likely some kind of plastic. 

That alignment part will be slid over the lamp assemblies while they are facing up and at the maintenance person, who can easily manipulate them into position to have the alignment part touching the PCB face. I have some measuring and noodling to do before I design and fab this out, but I suspect this will be the way to make this control panel upgrade a complete win. 

Missing a handful of bulbs to complete all 164 positions of the 1130 Console Panel

 BAD NEWS FROM THE LAMP SUPPLIER

The supplier who told me that my bulbs were on order and would be shipped next week, followed up today with an email informing me that the bulb is discontinued by the maker (which I knew) and therefore they were refunding my purchase. Drat.

I hunted down some other suppliers who claim to have stock on the 2114 bulbs and have ordered another 20 from them, but in the interim I discovered a box of 20 bulbs that I owned. Between the 100% success rate I had reusing the bulbs from the old holders and these new bulbs, I was able to complete all but two lamp assemblies. 

SIDE PROJECT BATTLING FIDDLY HARDWARE AND TARNISH ON A BRAINIAC K-30

I recently arranged a sale of a Brainiac K-30 as I slash the size of my collection of retro items. This is a derivative of the Geniac, a kit from the mid 1950s that was the introduction to boolean logic and digital computers for children of the 50s and 60s. 

The kit was a large masonite board, predrilled, and six round masonite dials that were also predrilled. These dials formed rotary switches using bolt heads as the contacts on the main board and staple-like jumpers on the dials. You could make various switches from the two pairs of rows and sixteen rotary positions. A battery and flashlight bulbs in sockets completed the active components of the kit.

Quite primitive, but through a series of increasingly complex sets of switches you wired up, solving more and more complex issues, the user could experiment with boolean logic and experience how digital logic could address a wide range of real life problems. 

The weakness of the kit was always the quality of contact between bolt heads and jumpers as you turned the dials to various positions. That weakness remains, but added to it is more than five decades of tarnish on the brass parts.

The buyer of the kit is a museum, to which I impulsively offered to wire up a three bit full binary adder to show the kind of problem this could tackle. Given the six dials that came in the kit, that was about the largest adder it might handle. 

Seemingly an easy task, I discovered anew the difference between digital logic and these switches. No resistors, no diodes, no inverters and in fact a signal did not operate in binary. That is, there was not a 0 and a 1 level on the signal. There was a connection, or there was no connection. No such thing as a 0 level connection. 

The boolean equation for a binary adder stage (except the rightmost) is A xor B xor CarryIn and there came my first design challenge. Implementing an XOR is a matter of wiring a switch on one dial to a switch on the other, but criss-crossing the wires so that a connection is made only if the dials are 0,1 or 1,0 but not if they are both 0 or both 1. 

However, how do you wire another XOR to that when you have one wire when the CarryIn is active but nothing when it is false? Instead, I had to produce two different signals from the stage to the right - CarryIn and InvertedCarryIn - where I had voltage on one of the wires but not the other at any time. 

Then I had to wire up the XOR driven by InvertedCarryIn to produce the sum of the bits for the case where no carry occurred to the right, which indeed sets the output to 1 if the two dials are 0,1 or 1,0. 

When a carry has occurred to the right, the output is an inversion of the XOR such that we get an output only when both dials are 0 or both dials are 1, but not when they differ. This is wired as a switch on each dial with the 1 positions connected together and the 0 positions connected with a different wire. That means four total switches are used to light the output lamp for a 1 value for this adder stage. One pair is powered from CarryIn and the other pair is powered by InvertedCarryIn. 

The boolean equation to calculate CarryOut and InvertedCarryOut were:

CarryOut =                                 (A and B) 

                                                        or

                                       ( (A xor B) and CarryIn )

InvertedCarryOut = (     (notA or notB) and InvertedCarryIn    )

                                                        or

                                     (    (A or B) and CarryIn    )

That required another eight switches, four on each dial, for a grand total of twelve two position switches for each binary adder stage. The rightmost position was easier because it had no carryIn to consider, thus I only wired the switch paths that were fed by InvertedCarryIn, which was itself hooked to the battery. 

The kit had an almost full complement of parts such as bolts, nuts, jumpers, bulbs etc but there were not quite enough of the jumpers to populate the third binary stage. I thus had to settle for a binary adder that took a pair of two bit values and produced a two bit output plus a carry signal. 

Building this and testing all the wiring was a bit more work than I initially had imagined, but once I was done it was time to deal with the poor quality of the connections. I tried to use deoxit spray and ensure the best fit possible, but the result was as disappointing as I belatedly remembered from my youth. 

The bottom line, however, is that I did wire this up to produce a full adder for a pair of two bit binary values. Satisfied, I documented everything and shipped it out today.

More than halfway done building lamps into holders

 PROCESS RECAP

Since my supply of new 2114 miniature incandescent bulbs is going to be delayed at least another week or so, I am reclaiming bulbs soldered onto my prior approach to a lamp holder - wire leads wrapped around a 2 position header strip then insulated with goop since the bulb can bend and twist bringing its wire leads together. 

Once the bulb is removed from the old header, it is cleaned and ready to solder into a new holder. To construct the holders, I cut two pin segments from a new header strip, insert one end in a breadboard to act as a jig, and snap the nylon holder down over the header segment. This creates a holder which has the two pins separated by a nylon barrier, two side arms that nestle the T 1 1/4 size bulb in place, and allows access to solder.

Fortunately, the bulb sitting in the holder needs only a very short segment of wire lead and it can reach the top of the header pin. Something in the range of 1/4" is adequate. That allows the reuse of the old bulbs since I can cut away twisted ends without loss of any bulb. 

The goop makes this desoldering much harder than if I simply had to heat and remove leads that were wrapped around the header pins. I make use of a large tip on my Weller soldering station to do the removal, transferring heat through the goop but gumming up the tip quickly. Lots of retinning, tip treatment and cleaning is needed as I work my way through more than 150 of the old bulb assemblies. 

Installation of the cleaned bulb in the new holder is quite easy. I use my thinnest tip on the Weller station, push the bulb down within the holder arms, push the lead in contact with the pin, apply the iron and solder the connection. A quick flip of the holder and I repeat for the other bulb lead and header pin. 

I set up a test station on the breadboard connected to my ohmmeter. Popping each new lamp into the station tells me if this is an open circuit, a short, or the bulb is displaying circa 10 ohms of cold resistance. I know that every lamp I build is working properly before I install them on the PCB.

STATUS

I have cycled between the three process steps - cutting and snapping header strip segments into holders, removing bulbs from the old assemblies, and soldering the bulbs into the new assemblies. This is tedious work due to the need to build 164 lamps for the fully populated IBM 1130 console panel. 

Partially populated board, unfinished holder below

I need to reclaim 66 more bulbs from old assemblies, move them into new holders, and then when my bulb supply arrives I can finish the last 16 lamps which illuminate the unused CE (Customer Engineer) and Synchronous Communications Adapter (SAC) positions. 

I don't have the SCA on my machine and the CE lamps are set up to display diagnostic signals by the use of jumpers when the CE is working on the system. I have better logic analyzer and scope tools, thus am unlikely to make use of the 8 CE indicators. 

TEST FIT CONTINUES TO LOOK EXCELLENT

From time to time, I check how difficult it will be to slide all 164 bulbs into the honeycomb matrix behind the display panel. So far, it has been pretty easy to wiggle it a bit and have all the lamp holders slide into their cells. 

Received lamp holders, beginning to build lamps for the IBM 1130 control panel

 VERY SATISFIED WITH THE NYLON LAMP HOLDERS

3DHubs.com is the manufacturer of the nylon lamp holders I designed with Autocad Fusion 360. The holders arrived today and I am very pleased with the quality of the holders that were produced. The prototype I had built by Xometry.com, the fab house associated with Autocad, was rougher and they only offered black. The new white ones very good and totally satisfactory for the job they will do.

Counting the lap holders that arrived today

INSERTING PINS INTO THE HOLDERS

I had cut apart standard sized header strips, although with round rather than rectangular shape pins, to form the two pin segments that fit inside the holders and mate with the sockets on the PCB. They snap into the nylon holder with a satisfying click, producing very good alignment when plugged in. 

RECLAIMING BULBS BECAUSE NEW SUPPLY IS WEEK OR TWO AWAY

I bought a supply of the 2114 miniature wire lead incandescent bulbs from Genesis.com but will have to wait one to two more weeks to receive them, apparently. I placed the order on April 12 and according to the web site, in stock items ship within 24 hours unless noted at time of order. No notification either at order or the next day when the email status informed me they were 'in fulfillment'. 

As it was a week later with no indication they had been shipped, I called to speak with the customer service group. He told me they had not been in stock and were on order. I asked him to check on an estimate of arrival from their supplier and he indicated it would be a week from today. 

The delay is reasonable and understandable, the only complaint I would have is that nowhere on the order status or in the various emails I received from the company did they inform me these were not stocked and going to take two weeks before shipment. Lack of communications left me uncertain and concerned. 

To move ahead, I decided to begin removing the wire lead bulbs from the current holders, which are just the header strips without any support structure. I did daub some insulating goop on the leads to protect against shorts if the bulb twisted to bring the leads into contact. That makes the removal a bit messier but the process is simple - just multiplied by 150+ to pull them all off the existing headers. 

INSTALLING OLD BULBS IN THE NEW HOLDERS

The process of installing the bulb is slow, requiring care to position the bulb inside the arms of the nylon holder then manipulate the leads one by one into contact with the pin for soldering. It will take a couple of minutes per holder, thus about five hours in total to mount them all. 

FIRST TEST FIT TO CHECK ALIGNMENT ISSUES

I installed the first ten lamp holders with bulbs into spots spread across the PCB positions fairly evenly, then did a trial fit of the PCB with lamps into the honeycomb matrix. It seemed to slide into position very easily. I am becoming quite confident that this will provide the ease of insertion and removal I want to have a truly maintainable console light assembly.

Glacial movement of supplies while I bide my time

 3D PRINTED LAMP HOLDER PRODUCTION

I had a quote from 3Dhubs.com to produce 165 holders for an attractive price, with a production completion date of April 14 and delivery by the 21st using a medium priced shipping option. 

I was contacted a few days ago by customer service letting me know that the manufacturing partner informed them that the job will take an extra day to complete - April 15. As a consequence, 3Dhubs.com upgraded my shipping at no charge to 1 day which was more than fair.

Today, when the parts should be shipping, the status remains 'in production' and not yet moved to 'quality inspection'. Hopefully they will not be further delayed. On the other hand, having shoddy unusable parts early is not a good alternative; happy to wait a bit to get good parts.

2114 BULB DELIVERIES

The bulbs were ordered from Genesis.com on April 12, listed as in stock and per their website should have shipped within 24 hours. It is now April 15 and the order is still showing 'in fulfillment' status. I can theoretically remove all the bulbs from my existing header strips and remount them on new strips in the plastic holders, but I won't have much tolerance for any that are damaged or can't be remounted.