Build Your Own Clone Message Board

Hi, just finished my first build. The pedal light comes on when activated, but it does not create a chorus effect in any knob position.

Hi jjones - welcome to the forum!

Have you adjusted the trim pot? Do you get any sound from the pedal when the LED is lit?

Adjusting the trim pot doesn't make any audible difference. If I go extreme counter clockwise or extreme clockwise it does cut off the sound completely though.

You've got chips in the wrong positions. Check the positions against the instructions. It looks like you have the 3102 and 3207 swapped, and the 4558 and TL022 swapped.

I appreciate your patience.. this is my first build. Looks like the chips were in the wrong position... I switched them around, but I'm still getting the same response out of the pedal. It comes on, but still no chorusing effect.

No problem! would you mind posting an updated pic of your build?

I dropped my iphone 4s in water, and it will be a few days before I can go and get it replaced. I will post a new pic later this week.

Do you have a digital multimeter or a signal tester?

I don't, but I can get one.

OK - looks like you have the chips in the right place now - if you originally swapped the TL022 for the 4558 you should not have damaged those two chips because they use the same pins for power. I'm not absolutely sure about the MN3102 and MN3107 although their pin outs are very similar so they should be OK. Just as long as you did not apply power with any of the chips reversed (pin 1 at pin 5 of the socket) in the sockets.

Looking closely at your pics it seems some of the joints on the PCB are a little solder starved. I would go over the board and touch up at least those joints up with reference to your pictures. It is also a good idea to give the board a really close inspection for bad joints and/or shorts/solder splashes, using a magnifying glass and good lighting. The joints on the jack sockets have not flowed out well (normally this is an indication of using an under-powered soldering iron or just not holding the iron in firm contact for long enough). It is possible to get no signal though the pedal because of completely open circuit 'joints' at this point.

Just checking - you are using a new battery that you have checked for output voltage? A new battery in good condition should put out over 9V with no load.

You say you hear 'no effect'. Does that mean that with the foot switch flipped to 'active' you can hear the dry signal? The chorus works by splitting the input signal into two paths - we'll call them the 'dry' and the 'wet' path. The wet path is delayed by a varying amount and then mixed back with the dry signal. The shifting phase cancellations between the two versions of the signal are what we hear as chorus. If you hear an un-effected or dry signal with the foot switch in the active position (just flip the foot switch back and forth to see if the signal disappears) then that means that the input signal is probably passing through the input pre-amp (IC1A) passing through the dry path R20 (47K) and also passing through IC5b (this is labelled incorrectly on the circuit diagram - it should be IC1B) - these are the two halves of the 4558 chip. If in one position of the foot switch you lose the signal then there is something wrong just in the signal path from the input jack - to the foot switch - through IC1 and R20 - through another section of the foot switch and out to the output jack and this is where you should concentrate your attention.

Unfortunately some of the circuit diagrams included in the instructions contain errors. For de-bugging refer to the alternate corrected circuit diagrams which I think were uploaded to the forum by Stephen.

To clarify..

I have used both a battery and the power supply, and either one makes the light on the pedal come on when engaged. When it is not engaged I get the dry signal, and when its engaged the signal does not change. It sounds the same whether it is engaged or not.

Well that is good news - it seems to indicate that the signal is routing through the pedal and at least part of the circuit is working.

Now to figure out what is not working. Lets break the circuit down into sections - the Low Frequency Oscillator, the Bucket Brigade Delay clock, the BBD itself.

For now lets assume that the input amp and the output mixer are working since you do hear the dry signal.

You can check the LFO by connecting a multimeter (an old needle type analogue meter would be best for this test) to the top of the Depth pot. This point should be slowly shifting up and down by a few volts (set the LFO Rate knob for min).

You could also use an audio probe to see if the input signal gets to the input of the BBD. There should be audio on the emitter of Q1.

Testing the BBD clock is a bit tricky without an oscilloscope. You could check pins 2 and 3 with a meter - I believe if the clock is running a meter will tend to dither at around 2.5volts.

Also check and set the trimmer for 4.5v on the top of C21.