Solder reflow plate project working, still working to hook up logic analyzer to the IOB6120

PROGRAMMING THE ATMEGA328 ON THE REFLOW PLATE

The solder reflow plate has a ICSP connect (3x2) that is used to download code to the ATMEGA microcontroller. I used a spare Arduino Uno as the programmer, hooking up the two ICSP connectors with cables. It completed successfully, after which I used my oscilloscope to verify that the crystal was oscillating at 16MHz driving the controller chip. 

SOLDERED ON THE OLED AND FIRED IT UP

I installed the temperature sensor and the OLED display board to the PCB. The only part I am still waiting for is a good main diode that protects the circuitry from a reversed 12V supply connection. I have a jumper across the diode pads for now.

The OLED lit up with appropriate output and I got it to start heating - the power supply kicked up to the 5A limit I set and the plate began to get toasty. I am satisfied with the outcome of this project, in spite of the hiccups along the way, and will move it into service in my soldering area once I install the diode. 

Reflow plate is operational

GETTING ACCESS TO THE 50 PINS OF THE SBC EXTENSION BUS

The IOB6120 (IOB) board has a 2 x 25 pin header on it that fits into a 50 pin socket on the front panel PCB. This is the extension bus from the SBC6120 (PDP-8 replica). Since most of the parts on the IOB are surface mount, it is very difficult to hook probes to the circuitry. While I have the means to attach up to four, real debugging requires many more signals to be captured.

My first cut at this was to buy a 50 pin ribbon cable, the type that was an internal SCSI cable inside PCs. I would hook the cable to the header pins on the IOB, use a special header with long pins on both sides to connect to the front panel socket, and then use another long pin header on the center socket of the cable to gain access for logic analyzer connections.

Alas, I forgot about chirality, introduced because the header on the IOB extends downward into the socket on the front panel. A cable connected to each will transpose the two columns of 25 pins, while I intend to have the columns connected as they are when the board is directly plugged into the front panel.