Placed 164 sockets on the backside of the PCB into which the lamps will be plugged

 REPLACEABLE INCANDESCENT LAMPS

Since incandescent bulbs have a short enough life that they need to be replaced as a routine matter, I designed this upgrade for the IBM 1130 to allow easy swaps when bulbs are dead. The bulbs I chose are T small wire lead style, which easily fit in the honeycomb matrix unlike the original IBM part that is press fitted into each cell. 

My board provides sockets for all the lamps on the rear side. With all the bulbs inserted into the sockets, they are steered into the honeycomb matrix while the board is pushed flat against the matrix. Replacing bulbs is simply a matter of pulling the whole board back, unplugging the bad lamp and inserting its replacement. 

SOCKETS BUILT WITH HEADER SOCKETS, BULBS ON HEADER STRIPS

I chose a very simple socketing system for the lamps, since they are wire lead type. I cut header strips into two position lengths, wrapped the bulb leads around the top of the pins and soldered them in place. The PCB has header sockets, also cut to two position size, into which the header segments are plugged. 

INSERTED ALL 164 SOCKETS ONTO THE BOARD

It was a tedious session this afternoon, where I cut apart socket strips into two position segments, hand placed them on the rear of the board and soldered them in place. Doesn't sound tedious until you realize this is 164 repeats of those steps. 

Rear of board, covering the right side of the 1130 panel

Rear of board, covering the left side of panel, with sockets installed

Right side of panel with machine status lights

Left side of panel showing the contents of six major registers

Installed 164 Triacs and 164 resistors onto the IBM 1130 incandescent lamp upgrade board

 STEP ONE IN CONSTRUCTION

The two hardest parts to install are the triacs and resistors. I expect that the best sequence is to put all the triacs onto the board, then add in the resistors. The triacs can slide around a bit as I maneuver them into place and might bump into the resistors. 

PROCESS

I added a bit of solder onto the large pads before applying the triac. This makes it easier to solder them into place and allows me to see the triac sink slightly as it makes a good bond. 

Using tweezers I placed the part in position and held it while applying heat and solder. Once the large heat sink of the triac was bonded to the large pad on the PCB, I soldered the ground and base leads to their small pads to complete installation of that triac.

I intended to have every triac perfectly aligned but no plan survives contact with the enemy, so there is a bit of variation in the placement. A very few are slightly rotated; more often the variation is vertical placement, if you call the side of the triac with two small leads the down side. 

First 96 circuits have triacs and resistors installed

The resistors were dead easy, even better than expected. I had none pop off the tweezers, none got lost, and they aligned very nicely with minimal work.

0603 sized resistor below left triac lead

FLAWS DISCOVERED ON BOARD

I did discover a few errors on the PCB. Some were silkscreen layer issues - a few triacs still had their ICxxx label displayed and one row of signal names were placed above the lamp socket rather than the signal pin, but those are largely irrelevant. Others were missing connections that I discovered as I carefully checked connectivity after each step of soldering.

I was missing a connection between the gate pad of the Accumulator Register Bit 14 and one of the resistor pads. That was easily corrected with a small jumper. I also missed a connection between the large 'anode' pad for the Customer Engineer 4 triac and the lamp socket pad. This was also corrected with a jumper. 

PCB arrived, ready to begin component installation and checkout

 PICKING UP THE PCB

After watching the progress of the box, I saw it delivered on Monday afternoon and arranged a time to drive over to pick it up that evening. After a bit of photography and video of the unboxing, I was ready to move onto the construction phase.

PRIOR TO PARTS BEING ADDED

You can see the board as it arrived, with its component pads, holes for connectors and labeling - white resist with black lettering. Since I received five of them, I sent one to an east coast museum where they are restoring another IBM 1130 system. 

PCB ready for component installation

Closeup to see labeling of signal pins and detail work

CONSTRUCTION BEGINS

Building this board involves placing and soldering the following on the board:

• 164 surface mount 0603 resistors (6.8K)
• 164 surface mount triacs
• 164 single header pins for logic signal inputs
• 164 dual header sockets for lamps to plug into
• 3 heavy duty wire terminal blocks for AC, ground and Lamp Test wire connections

Technique is important when soldering on surface mount components, if you want them to be well aligned and look neat. A reflow oven would make use of the solder surface tension to pull the parts into good placement, but I don't have an oven big enough for this 17 1/2" wide PCB. 

In addition, the sequence of installation is important, as the header pins and wire terminal blocks would get in the way of placement and soldering of the surface mount parts. I chose to solder on the triacs first, then added the resistors, before installing all the connectors. 

I will tin the large pad where the triac body will be soldered, but not the pads where the gate and cathode are attached. I will do this because I could mechanically hold the triac by the sides while I heated the solder to make the triac sink down and solder to that large pad. Holding it properly would put the gate and cathode leads in the right place for easy soldering.

A similar process, tinning one side of the pads for each resistor, will allow me to place the resistor well and solder one end. I expect this to be more fussy than the triacs because the means of holding the resistor is limited and it could easily pivot up leaving a vertical gap under the far side of the resistor. I think that I can push down on the far end while heating the near end solder to pivot the resistor back down in proper orientation. 

PCB box approaches, on target for Tuesday arrival

FINALLY THE PCB IS NEARING ME

The PCB flew through the shipping system, leaving Hong Kong within a day of beginning its journey in Shenzen. Expected delivery was Tuesday March 30th at that time, and as it cleared US customs in LA on Saturday, that seemed very realistic. Sunday morning it was in the DHL gateway in LA, thus still on track. 

Los Angeles is roughly 400 miles from my location, basically a few hours truck drive from there to a distribution center and then out on a van for delivery the next day. I expect it to be on the truck either overnight today or Monday in order to maintain the targeted delivery date.

PCB jumps from 63% done and target of April 2, suddenly complete and waiting shipment

 This morning when I checked the boards were listed as 63% complete and this evening they jumped to 100%. It had appeared to me that the completion  percentage was simply incremented 1/16th per day based on the target of 16 days for production. This hinted that the board was contracted out to another fab, limiting the visibility that all previous orders had offered into the detailed manufacturing steps.

The PCBs must have arrived at PCBway or be ready for direct shipment from the actual fab plant, without advance notice of faster than forecast progress, thus the leap from 63 to 100 percent. Not that I am complaining, of course. Happy to have them arrive sooner, in fact. 

Once they are tendered to DHL I can get a better idea of the arrival time of the package, particularly once it passes through US customs next week. 

Components arrived as I wait for a seeming eternity for the PCBs to be completed

 FAB WORKING ON THE PCBS

It seems like the proverbial watching paint drying, but I check in every day to see the glacial creep of the progress indicator for the production of my boards. Today it reached 57% on its journey to the predicted completion on April 2nd, after which they have to be shipped across the ocean. 

COMPONENTS ARRIVED AND READY

It wasn't worth the effort to harvest any of the surface mount 6.8K resistors, nor to remove the header pins and sockets. I now have several hundred 0603 sized resistors, rows of header strips and rows of socket strips waiting to begin installation on the PCB. The large wire terminal blocks also arrived this week.

STAYING BUSY

In the interim, I am cleaning out excess possessions and donating or selling them off. Goodwill received over 20 large garbage bags full of clothing, for example. I sold a Tektronix 7854 oscilloscope and am in the process of selling a couple dozen plug-ins. 

I completed some work on the thru-wall air conditioner in the den, which involved carpentry and a lot of muscling tools and materials around. Just a matter of going through the long term list of tasks and repairs around the house, but it keeps me busy while I wait, wait and wait some more. 

Prep work while waiting three or more weeks for the new PCBs to arrive

 HARVESTING USABLE PARTS FROM THE CURRENT PCBS

I used my hot air rework tool to carefully remove all the triacs from the three existing boards, since these add up to a bit of money for 170 positions. In addition, of course, I unplugged all the socketed light bulbs and saved them.

Triacs on the bottom after removal from the PCB above

I made no attempt to save the header pins, sockets nor the 6.8K 0603 sized resistors as these amount to pocket change worth less than the time to remove them and clean them up for reuse.

IMAGINING HOW THE NEW PCB WILL LOOK

Colored image of the left side of the board

I took the image from the PCB design tool and filled some sections with colors to approximate what my board will look like when it arrives. The resist layer is white and the text is black, so I didn't get this fully correct (the text in the image is brown). 

The grey areas represent the tinned surface where the Triac will be mounted. The black squares are the header pins where the signal wired plug in.  Smaller black rectangles show where the 6.8K resistors will be visible after soldering. The blue blocks are the beefy terminal blocks where I attach the power, ground and lamp test wiring for the entire board. 

The sockets for the lamps are mounted on the back side, seen here as yellowish white rectangles near each triac. If I had good 3D models of all the components, I could have used the tool to produce a 3D rendering of the board with parts mounted, but I don't have such files for the triac nor the wiring terminal blocks.