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.