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Project 21 Phase Shifter

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I built the Phase Shifter from Craig Anderton's book Elect Proj for Musc.

I put it into it's own metal box and it worked. Recently I mounted it on a metal face plate along with an AC Adapter and a Ring Modulator f/x. Now the Phase Shifter does not work.

When I connect the output to the amp, and turn the Phase on, I can turn all the knobs and the freq sounds respond to the expected effects -- only problem is my guitar signal is not making it through the system. The sound I hear is simply a flat freq created by the Phase (not loud or distinct.)

When I flip the "AMP Through" switch I do get my guitar through the amp. It acts like the guitar signal is not making it through the Phase system.

It did work before I mounted it. Wondering if anyone can direct me for "what to look for or troubleshooting direction." Much Thanks.

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I recommend checking all aspects of the grounding. You might want to go back to the chapter in EPFM that talks about common construction techniques, particularly how ground and bipolar power supply connections are handled.
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Thanks for your earlier suggestion.

Rechecked all the grounding, connections, even resoldered and replaced some sheilded cables. Here's what I get:


With output to amp, guitar in input, I turn the unit on.

I get an oscilating freq -- no guitar signal

When I turn all the dials each dial does change the action of the oscilating freq.

add/sub switch responds as expected

soft/bright switch responds as expected

fast/slow switch responds responds as expected

Output dial responds with louder or lower signal

Speed dial responds with slower warble sound or faster

Etc etc with all the dials, they all seem to do what their supposed to.

The guitar will play when the Through switch is turned to AMP

It acts like the guitar signal is not making through the system OR

Major component(s) is(are) not working -- THIS IS WHERE I'M NOT SURE WHAT ROUTE TO TAKE????

ANY suggestion would be greatly appreciated. THANK YOU VERY MUCH.

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It's soooo difficult to troubleshoot via email. You gotta have the thing in front of you with a scope and soldering iron to do it right.


I don't know if you could have fried a part or something during the conversion process, but I'd bet it's something simple, like reversing connections on a jack or something. You may be digging too deep, look for something obvious.

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  • 2 weeks later...

Well . . . I gave up on the old Phase Shifter, nothing I did would correct the problem so I purchased the PAiA kit version.

I took my time and soldered carefully. Does not work -- all I get is a pulsing popping. Output seems to make the popping louder. Freq makes it faster or slower -- all other knobs do not appear to have an effect on the pulsing pop.


I must admit I was confused by the 4739 Adaptor instructions especially where "Putting it Together" stated "If the application board has connections to pins 2,3,4,11 & 12, clip off the corresponding pin on the adaptor before installing it."

I did not clip any of the pins (I simply did not understand what it was asking.If this is THE possible problem please tell me in OTHER WORDS what they are asking)

Can you give me a few other possibles? Greatly appreciated!


Neil Chapman

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