Help! Loophole with JakeFuzz vibrato mod issue

[tmiso]

Hello!! First time posting on here and I'm hoping someone will be able to help me out!

So I finished the loophole with jakefuzz's awesome vibrato mod (diagram below) and I'm running into some issues.  The pedal bypasses fine while nothing is engaged.  When I hit the record switch, the green LED lights up instead of the red and still get output to my amp which can be effected by the volume potentiometer. After I disengage the record switch and hit the play switch, the green LED lights up again but no recording is played. While the play switch is engaged, I get a dry signal which is effected by the dry and volume potentiometers. I have triple checked all the components and ensured I have no shorts. I've even bought a new ISD1020 IC to see if that was the issue. Can anyone help me out or point me in the right direction to get this thing working?? Thanks!!!

[thomasha]

When you record both green and red should light up.
Check your switching, I made some mistakes in mine too. I got confused with the 2 DPDTs and had to recheck them more than once to get it right.

You can use your multimeter and check if the pin that receives the record command has its voltage changed when you active the switch.

If the switching is working, a probe would help identify where the sound is disappearing.

[JakeFuzz]

The red LED not turning on tells me the record node is not going to ground when the switch is pressed. This would also be consistent with the no-output behavior you are seeing. If that node doesn't go low the chip never begins recording the loop. Can you confirm with a multimeter when the pedal is off and not plugged in? How does the wiring on your safe switch look? If you don't need a safe switch the pads shown in the mod diagram should be shorted together.

[tmiso]

Thanks for the responses!! I really appreciate it. I rewired my safe switch and the lights now function properly! But... I am still having no play back like before. When I get home I will poke around with a multimeter and see if the issue is the one you described above. Could there be a different issue now that the safe switch is properly wired?

[JakeFuzz]

Okay so it sounds like more than likely the right pins are going low when the record switch is pressed. If you get a chance check voltage at pins 4,9,10,27. These should change from high to low when the record switch is on. The next thing is going to be to check the supply voltage on the ISD chip. Check voltage at pins 28 and 16. Because the mod calls to isolate these nodes from the main voltage regulator (the two trace cuts) on the board for the vibrato and detune function, there is a possibility that the mod board is not supplying the proper idle voltage. 28 and 16 should be high (5V) when the detune and vibrato function are not being used. If the voltages are not high check the green wire connection on the mod board. If that connection at the mod board (or the emitter of the 2N5088) is not high then the issue is with the mod board and we can pick up the troubleshoot there.

[tmiso]

Sorry for the late reply, been very busy with life and just got back to this. ran the tests that you recommended. Voltage at pins 4,9,10,27 are at 5 volts. However, voltage at pin 28,16 and emitter for transistor 2N5088 is only 3.6V--- sometimes it is 1.2V not 5 when detune is off. Green wire to mod board likewise is 3.6 or 1.2V. Thanks again for all your help. I really appreciate it.

[JakeFuzz]

Okay so the issue is most likely with the mod board or wiring then. That voltage should be 5 volts when everything is completely disabled. Check the wiring at the mod depth and detune pots. Check the voltages at the 3 pins of the transistor. It sounds like we are losing voltage somewhere between the regulated input and the output of the mod board. If you temporarily lift and connect the green and blue wires off of the mod board does the record circuit work?

[tmiso]

Finally got back to this today. Rewired at the mod depth and it records and plays back!! So excited. The only thing is the mod pots seems to have virtually no effect over the sound of the playback. Not really getting the warble that I have heard on some demos on here. I did feel as if I heard some vibrato while the detune switch was engaged. I believe the mod pots did have some effect over this sound. Additionally, to record the detune pitch must be set to max. Think they is further issues with my mod wiring? Again thank you sooo much for your help!! Definitely would not have been able to get this far without you. I really appreciate it.

[JakeFuzz]

How did you rewire the mod board? If you still have the green and blue wires lifted and connected off the board the mod board will not be in the circuit. If the mod board is still connected to the power rails of the ISD chip (how it is shown in the above mod diagram) and you still don't get any effect then something is up with the mod board. Do you have access to an oscilloscope? If you do then taking a look at ISD supply voltage should give you a good idea of whats going on pretty fast. Use a high impedance DC couple channel to measure the voltage on the emitter of the 2N5088 with different mod settings. You should see a wave that changes amplitude and frequency with the mod controls.

With a DMM measure the voltages on the transistor pins and the CD oscillator chip to make sure everything is being powered. Does the detune switch and pitch control work on the playback signal? If so it may just be an issue with the oscillator. The warble should be very strong (even too strong at certain settings) so it sounds like something isn't working properly.