Light panel mounting completed, installed and tested

FITTING THE CLAMPS AND HOLDERS FOR THE UPGRADE PCB

I made use of rubber gasket, formed as a U channel so that it could slid over the edge of the clamps and provide both protection and some thickness to be pressed down when my clamp is engaged. There is a clamp for each side. 

The clamp itself is fitted with one lip hooked on the front facing edge of the Lucite blocks of the panel, the other lip behind the PCB holding it pressed against the rear face of the honeycomb. A thumbscrew tightens the clamp into place. 

I did need an extra layer of rubber to get a firm fit, but everything is nice and tight, easy to get the board in and out. 

INSTALLING THE PANEL AND HONEYCOMB INTO THE CABINET

The Lucite blocks on the left and right side of the honeycomb have screw threads allowing them to be bolted onto the metal supports inside the cabinet. This places the display panel on the face of the cabinet and secures the assembly prior to fitting the lamps. 

I couldn't get a small screwdriver into one side of the cabinet, as it is restricted due to the Emergency Power Off (EPO) pullswitch and the terminal block for Lamp Test and AC Power. I had to remove the EPO plate and switch to get be able to screw in the lucite. 

The clamp on that side would not fit under the wire terminals going to my PCB, but with them removed temporarily the clamp slid right into place. The wires were put back and hooked to the PCB. 

WIRING THE POWER AND LAMP TEST WIRES

Heavy wire brings the common 7.25VAC power that drives all the lamps when they are illuminated. This is produced by a step down transformer power supply inside the 1130 which has one side of the output tied to the common signal ground, the other oscillating plus and minus 10.25V to produce the 7.25 RMS that illuminates the lamps during the positive going half cycles. 

There is also a Lamp Test line which is either held at ground or fed 3VDC. Resistors isolate each SCR trigger from this common line, allowing the individual signal lines to fire just one SCR while Lamp Test fires all the SCRs simultaneously. 

I provided three heavy clamping terminals to connect the AC, common ground and Lamp Test wires. These were wired over to the terminal block on the 1130. 

HOOKING UP THE SIGNAL LINES FOR THE INDIVIDUAL LIGHT CIRCUITS

A pin on the rear of the PCB is provided near each light position, to feed to the nearby SCR that controls that bulb. These are arranged in the same spacing and positions as used with the original IBM mechanism - horizontal boards mounting up to 16 bulbs and SCRs for a half row of the display panel. The signal wires have round push clips on them, which slide neatly over the pins on my PCB. 

I pushed them all on and had a completely installed board securely held in the cabinet. All was ready for testing. 

LAMP TEST AND COMPLETED PANEL WORKING PROPERLY

I fired up the IBM 1130 and flipped the Lamp Test switch under the top cover. All the bulbs lit up showing that the bulbs were all working. The switch is under the cover as part of the CE (Customer Engineer) group of switches that are considered service/maintenance tools. 

I displayed memory contents are some locations with known contents, then stepped through some instructions to verify that the register contents and system status is being displayed properly on the panel. I am preparing a video to load to my YouTube channel that will show the project and successful test.