Roland DB-500 no sound

[pontiacpete]

Ok, I needed to back track to the DSP board to IC4. The signal at the positive ends of C39 and C31 is a very strong signal 2/3 larger than the in put signal at the middle wire of CN1 on the DSP. But from there something happens to it. On pin 12 of IC4 signal is reduced to the size at input CN1. Pin 13 there's no signal and on pin 14 the signal is much smaller and very notched. I pulled the DSP board and checked the connections from C31 thru R27 to Pin 13 and with the ohm meter they show that they are connected. I trace the signal for C31 to R27 and it is fine, large and the same. The other side of R27 there's nothing The resistor measures 33k.
So this sounds impossible, as Mark has already said. But how can this be?
What's going on here?

[MarkusBass]

So this sounds impossible, as Mark has already said. But how can this be?

Pete, this is a very complex amp - it's like computer. In order to be able to fix it you have to understand at least a little bit of digital audio processing and how opamps work. Without it the repair will be very difficult (it will take ages).
In order to understand the problem that you reported now, you should know and understand the internal structure of UDA1309. There are most probably input amplifiers for left and right channel. Pin 13 and 14 are the inputs and most probably there is a "virtual ground" on the pins so measuring signal there makes no sense (there is 0V on virtual ground). This is how opamps work. The outputs of the input amplifiers are pins 12 and 15. And this is the place that you should look for the signal. Analog outputs are pins 21 and 24 and this is another place where you should look for the signal. This will allow you to verify whether IC4 is working properly.
But.....
You haven't specified whether you use settings from MEMORY "A", or MEMORY "B", or you are testing the amp in MANUAL mode. If you use settings "A", or "B" there is a chance that there is nothing wrong with the amp. There is a big chance that someone (maybe it was you) has stored incorrect settings (very low volume) in the memory. So, tell us how you are testing the amp. Do you switch between setting "A", or "B"? In that case I suggest reading at least the user manual. When you read it, please find UDA1309 datasheet and read it too.

Mark

[pontiacpete]

Thanks Mark!, a look at the manual got my signal back on the headphone jack , master volume... I just did the factory re-set.
Sort of back where I was last week but this time I can trace the signal all the way over to Q11 and Q12, it's on the both bases of each of these but I'm not sure if it's base 1 or 7 , yet.
THere isn't much of a signal on the rest of the pins.

EDIT: also when I touch pin 2 with the probe theres a little click sound out of the speaker.

[pontiacpete]

Ok On Q11 there is -67vdc on pin 2 that's the little click. But on Q12 there was no high voltage on pin 2 or any other. This led me to R25. Opened.
Replaced and now we have sound.
Thank you so much Mark for your help and your patience!! Much appreciated.

[MarkusBass]

If you are still interested why on the input of the opamp there was 0V and despite no input voltage the opamp worked, here is a very simple explanation:
https://www.quora.com/What-is-meant-...d-in-an-op-amp

Mark