Hi Brach,
let’s see:
So I checked the LEDs, they appear to be fine with the diode tester.
R14 is also fine.
I did reflow some of the solder joints, especially those of the micro controller, pin 15 looks good, all legs are properly seated.
Transistors:
Depth all the way down, mix 50/50
Q1 pin1 no voltage, Q2 no voltage
pin2 ca 700mV, both sides
Q1 pin3 no voltage, Q2 022mV
Depth up, Mix 50/50
Q1 pin1 no voltage, Q2 pin1 no voltage
Q1 pin2 fluctuating between ca 150 and 700mV, Q2 pin2 between 0 and ca 700mV
Q1 pin3 two random numbers followed by OL, Q2 same.
second measurement, because I got suspicious:
Depth @ zero, mix 50/50
pin1 no voltage on both sides
pin2 again 700mV on both sides
Q1 pin3 041mV, Q2 022mV
Depth full, mix 50/50
Q1 pin1 zero mV, Q2 pin1 zero mV
Q1 pin2 250-700mV, Q2 pin2 0-700mV
Q1 pin3 as before two random numbers followed by OL, Q2 pin3 same.
My multimeter is a fairly inexpensive one, so it’s certainly not the most accurate, but it seems to me, that Q1 and 2 do indeed behave differently.
As the mix dial isn’t exactly precise either, I do consider the possibility that the difference in voltage between Q1 and 2 might also have to do with mix knob not exact in the middle, but I tried to set it so both LEDs flash the same.
The random numbers on pin 3 seem funny to me, but since they occur on both Q1 and 2 I assume that’s probably fine. With depth all the way down the apparent difference between Q1 and 2 seems to be the voltage on pin 3, which is in fact absent on Q1 (second measurement was different. God knows why).
With Depth up both Q1 and 2 also behave differently, both go up to 700mV, while only Q2 goes all the way down to zero.
So, without knowing much about anything, looking at these measurements I get the feeling that Q1 is funky. I might get a new set of those, and replace them. This time I’ll be using sockets though, as it makes things a lot easier.
Do you agree with my conclusion?
Maybe I’m just trying to ignoring the uncomfortable third option, which might indeed be a faulty microcontroller. I’ve seen that your software is PC only, but I’m on Mac. So I’d have to find a PC for this purpose first. Well, let’s hope it doesn’t come to this.
But I have to say, as annoying as all of this is, it’s also great fun. I feel a bit like Sherlock Holmes 🙂
Thanks a LOT for your help 🙂