TapTation and Echobase problems

[PBE6]

I've been asked by a friend to install the TapTation controller on his Echo Base pedal. I'm going with all the simple choices on this mod to avoid extra switches and such. I've read through a few dozen posts on the large Echo Base and TapTation threads, but none of them seem to address the main issue I'm having.

Here are the Tone God's app note and data sheet for the TapTation controller:

http://www.thetonegod.com/tech/datasheets/taptation_pt2399.pdf

http://www.thetonegod.com/tech/datasheets/taptation.pdf

And here's a schematic for the Echo Base:


And some questions:

1. Looking at the app note, I understand that to use the tap tempo function I need to connect pin 5/6 on the MCP41100 to pin 6 on the PT2399. This is done by removing the Time pot from the Echo Base PCB and connecting the MCP41100 to either hole 2 or 3 (middle or rightmost) on the PCB. I believe hole 1 on the PCB should be left unconnected to completely remove the Echo Base time (and modulation) control from the circuit. Does anything need to be done with pin 4 on the PT2399? The Echo Base schematic shows that it is grounded so I don't think anything needs to be done with it, but I just want to make sure.

2. I've read that using the PT2399 (Echo Base) modulation can adversely affect the delay time accuracy due to the extra resistance, so I'm using the TapTation modulation control instead as per the app note. If I have removed the time pot from the PCB as noted above, the mod depth pot on the Echo Base will no longer be functional and can be removed, correct?

3. Now to the main issue, the Tap Tempo function doesn't seem to be working properly. The first set of taps seems to be ok, but then successive taps only seem to make the tempo stay the same or go faster, even if the taps are slower than the current tempo. Also, the indicator LED I connected to the TapTation through a 10k resistor is blinking at a different rate than the tempo no matter what it is. And failing the TapTation modulation knob up or down makes the timing go screwy.

I know there's a bunch of issues there, but does anyone have any pointers? I'm kinda in the dark on this one.

[PBE6]

Anyone had similar problems using the TapTation controller with the Echobase?

[slacker]

Points 1 and 2 are correct, you just remove the time pot and connect pin 5/6 on the MCP41100 to pin 6 on the PT2399, you don't need to do anything with pin 4 of the PT2399. If you're not using the Echo Base's modulation you can remove the mod depth pot and everything else that does the modulation U1 and all its components and the other stuff that was connect between it and the PT2399.

I don't know what might be causing your other problems but they're not Echo Base related. Sounds like either something is wrong with the taptation chip or it's not wired up right. I would breadboard up the application circuit from first datasheet, set it to quarter notes and see if you can at least get the LED blinking at the rate you tap.

[PBE6]

Thanks slacker, good and sound advice. I'll try to tackle this one tonight.