04 May 2023

No output from Arduino TVOUT examples

I am in the process of reverse engineering an industrial monochrome 12" monitor, mainly trying to figure out the pinout to drive it.

My initial analysis of the circuit, based on TDA1175 and TDA1180, concluded that it needed a composite video. So I programmed the PAL sample of the TVOut Arduino library on a Nano (clone) and got nothing. I got no signal on the TV, and nothing was moving under the oscilloscope scrutiny.

The library is scarcely documented, but reading here and there I understood that the resulting circuit was originally meant to produce overlay text on an existing video stream. This means that the Arduino sketch needs a sync input to stay ... in sync. Without an input sync, there's no composite output (this was confirmed later).

I checked the code and in the setup() portion there is this initialisation call:


Well, changing it to remove the OVERLAY requirement like this:


Recompile, reflash ... and the composite video comes out.

Green phosphors here I come!

27 March 2023

IC decapping with paint remover heat gun

I'm not sure where I read about an easy way to decap integrated circuits with heat, but it's certainly not three years ago (when the author published his demonstration video):

Well, while looking for something else in a storage area I found a good candidate to try the same experiment, but in WDIP package: a part marked R3268B with no daatsheet on the Net.

It takes more time to setup the heat gun (paint remover) that doing the job itself. The plastic case gets brittle with heat and it breaks in small pieces. Be careful they don't fall inside the heat gun.

This is the result of my first exposed IC:

I think I was unlucky as something covers the active area. The other side is uniform, like a large ground plane. I could see that pins were quite thick, so perhaps the IC was a motor driver or something that carried large currents. I'll try again with other chips.