Feb. 9, 2015

Let's open up one of these beauties and see what's inside.

I started by finding the eleven nuts on the back of these panels. The top and bottom groups of four hold the metal mounting brackets on the panel. Removing them allowed the brackets to be removed. Across the middle there are three more nuts that hold the back on. Removing the nuts allowed me to pry the front/shadow mask assembly from the back.

The circuit board was then removed from the back. As noted earlier the front of the circuit board is encapsulated with an approximately 3/16" layer of silicone.

The back of the circuit board is also waterproofed with a thin conformal coating.

At this point I began the slow process of removing the silicone using an xacto knife and LOTS of patience. Removing the silicone revealed the circuitry below.

To my surprise there were only two types of chips on the board. The board held 48 ST2226A driver chips and 6 74HC245 bidirectional buffers. There were no other active devices on the board. I expected to find at least a microprocessor or a decoder chip but other than a bunch of resistors and caps there was nothing else. No micro means that reverse engineering the panel should be MUCH easier.

Next up - Reverse engineering