Wolfo! wrote:I passed the calibration of the i/o board. Now I'm trying to calibrate the filter boards, but I'm encountering problems.
- Bridges between G-H and I-J are set
- Only psu, io board and filter board inserted
- Filter board has the bridge.
Correct, this is the vocoder in the most simple configuration:
- bridged filter board (input connected to output)
- bridged backplane (G-H and I-J connected)
- power supply (+/- 15V and +/- 5V)
- input/output module
Wolfo! wrote:When following the calibration procedure (blowing in the mic) I have absolutely no output from the device, measuring on the out jack. Turning the volume up/down briefly distorts the scope "flatline". Mic volume is at max.
Inserting a sine on the IN pin of the filter board has no result (no output).
As discussed in a private mail, this is not OK.
So please see below the schematics of a filter board:
Please can you put an oscilloscope on IC2 pin 14 and IC2 pin 8 and post some screen dumps? Do this also for IC1 pin 8 and IC1 pin 7.
If you have decent signals here, the filter boards are fine.
Due to elimination now only the OTA's (CA3080) remain. Unfortunately there are fake copies on the market.
But please post the requested screen dumps before we draw conclusions.
Wolfo! wrote:One more thing: The leds are on when nothing is connected (about 50% of the brightness of the power led). On both lpf and hpf I've followed the instructions and connected all the grounds together: these leds are the brightest (about 50% of the power led). On the other filter boards the ground of the led is connected separately to one of the grounding connections of its filter board. (I use connectors, it was easier to apply a separate connector on the led ground) These are less bright, again about half as bright as the two boards with grounds grouped.
Looks correct, on both vocoders I did make, the LEDs are slightly on when there is no input and blink depending on the signal level. I do not notice intensity differences at the different LEDs. And the connection of the ground seems to have nothing to do with it. Please check R33 (22 K), R34 (120 K) and R35 (1 K).
Wolfo! wrote:I guess something is wrong with the io module, but I have not enough knowledge of the thing to test.
OK, let's do some checks on the ipunt/output module.
Please can you put an oscilloscope on IC16 pin 6 and IC18 pin 6 and post some screen dumps?