So I was having an evening messing around with the CD32 and installed an ESP8266 unit inside it so it would connect to my Wi-Fi. I had everything all configured and was just about to start testing when my screen went white. I powered off the CD32 and powered it back on, only to get a blank screen, no sign of booting and the CD drive was not spinning up either. I was not very happy!
Anyway, I made my way to google and had a search around and came across a page that was talking about a voltage detection circuit on the CD32. This circuit made sure that 5V was present on the board and if it wasn’t it would halt the startup of the machine. This seemed to be a possible candidate for my issue so that was where I started.
Firstly I checked that the power supply was supplying the 5V which it was. I then checked various locations on the board where 5v should be present and they all checked out too. So it was now time to concentrate on the reset circuit.
I grabbed the schematic for the CD32 and found the circuit diagram for this part of the machine:
According to the article I read, U14 could sometimes be faulty and could cause this issue. But to test this I measured the voltage that was entering U14 on pin 2. This should measure ~5V but instead was measuring 3.7V, because of this, pin 3 was LOW, and therefore the machine would not boot. To test this out I grabbed a jumper wire and connected a known 5V source up to pin 2, immediately the green light went bright and the CD32 booted. So now I knew the issue, but what was the problem? There are only a couple of components before U14 that could affect the voltage, a 10k resistor, and a 0.47uF capacitor. I have seen many electrolytic capacitors fail before but this one was a small surface-mount capacitor. It still seemed like a likely candidate though so it got swapped out.
And after re-assembling enough to test the machine, sure enough, it fired back into life. I was so happy that I managed to recover the machine as I’ve really enjoyed messing around with it. Now back to connecting this Amiga up to the internet at a staggering 115200baud 🙂