Rebote 2 delay, REP pot not working

[ypelletier]

Hi,

I'm a beginner, it's only my 3rd project.

I built the "Rebote 2 delay" ( http://www.tonepad.com/getFileInfo.asp?id=50 ) on a perf board from the schematic (I didn't use a ready made pcb).  It seems to work fine except one thing:  the REP pot has no effect at all on the output.  There is always one single repeat (the original sound, then a repeat) whatever the REP pot is set to.

The pot doesn't seem defective (the resistance between center lead and outer leads varies from 0 to 100k).

I added a 27k resistor in parallel with the 15k resistor to try the "endless repeats" mod:  it had no audible effect on the output.

With an audio probe, I found an audio signal at each of these pins (on the PT2399):  15, 9 , 12, 14.
There is also audio signal where the REP pot is.

For what I know, the voltages on each pin seems fine:

On PT2399:
pin 1: 5.05 V
pin 2: 2.52 V
pin 3: 0
pin 4: 0
pin 6: 2.53 V
pin 7: 0.12 V
pin 8:  0.7 V
pin 9 to 16:  2.52 V

On TL072:
pin 1: 4.42
pin 2: 4.42
pin 3: 4.37
pin 4: 0
pin 5: 3.28
pin 6: 4.02
pin 7: 4.41
pin 8: 8.90

Any idea of what I should check next?

Unrelated questions:

There are two .005 microfarad capacitors in the schematic, but they are not in the part list:  is .005 microfarad the correct value?

Should the digital ground be linked to the analog ground?

Thanks!

[arma61]

Hi

I can only quote Slaker (he's the master of the PT2399!  )

"Double check the values of all the resistors around pins 13,14,15 and 16 of the PT2399. If you've accidentally switched either the 24k or 47k with one of the 12ks you'll have this problem. Basically with the values switched instead of being amplified each repeat will be reduced in volume, so it's impossible to get more than a few repeats."

About digital ground, if you look at the PCB on the Tonepad layout they're connected, so I gess they have to! 

Cheers
Armando

[ppatchmods]

For endless repeats you want to lower the value of the 15k to about 10k or so. Adding resistance could cause less repeats.

[arma61]

I added a 27k resistor in parallel with the 15k resistor ....

that should be about 9k, ins't it?

[ppatchmods]

Yeah sorry...didn't notice it was parallel