I recently replaced the RIOT chip on the Atari to fix a joystick issue. Fired up the Atari today for a game and the audio has now stopped working.
After reading through various forums it looks like a common problem with either the inductor L201 going open circuit or the polystrene caps C206/C207 going faulty.
Tested the inductor and didn’t see any issues. Didn’t have a proper capacitance meter but they both looked open circuit. Since these are polystene caps they are not easy to find.
Now is a good time to move away from the old RF modulator and convert to SCART. I still have a CRT TV with SCART.
Read through tons and tons of threads on doing this and there seem to be multiple diagrams to do this with varying circuits from easy to complicate, required another CD4050 chip.
Eventually came across this schematic from AtariAge forums which looked promising. I had all of these components lying around and put it together on a piece of veroboard.
Also found a layout for my exact board which made connecting up it a lot easier.
Model C012283. Rev B. Schematic here.
Connected up the 5V and GND to the closet points that I found on the schematic.
To wire the the output to the SCART connector I used this diagram I found on here.
Connected pins on SCART:
- Pin 2 & 6 to audio
- Pin 20 to Luma
- Pin 15 to Chroma
Wired up and connected to the TV, powered on…..success!
Great picture and audio is back!