Build Your Own Clone Message Board

Hi everyone. I put together the Classic Phaser and when the pedal is engaged I get no phaser effect just straight guitar. LED comes on but no effect. I've adjusted the trim pot with the effect pot all the way up and half way up (just in case). I get sound when pedal is bypassed as well.

This is my 20th pedal so I have experience doing them. Checked all of my solder joints. Verified that the diode, the electrolytic caps, and the op amps are all oriented correctly. I guess I'm missing something but cannot figure out what.

Pics below. FYI - They are oriented vertically on my computer but when I upload they are horizontal. IDK...

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-Jamie

Hey there!

Have you built any phase 90s before? The working range of the trim pot can be extremely narrow depending on the jFETs. Make sure you turn the rate up and strum your guitar while tuning the trimmer. Turn it very slowly.

Do you get any phase shift while you are strumming and turning the trimmer? Sometimes when the LFO isn't working, you won't get any phasing, but you will hear a phase shift when you sweep the trimmer.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

I’ve built the Phase Royal with the 4-stage JFET mod (as well as the 8-stage and the Optocoupler). Building the Classic Phaser for a friend. I strummed the guitar and turned the trim pot with the effect pot all the way up. No phase at all.

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-Jamie

Anyone have any other ideas? Could the trim pot be the issue? I have another 250k trim pot i could replace it with.

_________________
-Jamie

Do you hear any change at all while turning the trim pot?


Sent from my iPhone using Tapatalk

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Pedal building is like the opposite of sex. All the fun stuff happens before you get in the box.

Not that I can tell. It sounds like my guitar signal when bypassed.

EDIT: I just went back and checked - turning the trim pot very slowly while strumming produces no change in sound. It's just straight guitar. No phase at all.

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-Jamie

Sorry for the delay.

Are you able to take some voltage readings? Need to determine if your LFO us working. IC6 is the LFO. Take DC voltage readings to see if the voltage on any of the pins is oscillating.

While you’re at it, you should check the voltages on the remaining ICs too. In general, you should have 9 volts on pin 7, 0 volts on pin 4, and about 1/2 of pin 7 on pins 2, 3, and 6.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

No worries. Thanks for the reply. I will check it and reply (may not get to it tonight). FYI - if i did not say, i replaced all of the IC's with some I had (they were the 741 - the kit came with TL071) and no change.

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-Jamie

Yeah, I'm not worried about bad ICs. It's usually other things that throw the voltages off.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Gotcha. I’ll check it when I have a minute and reply back. Thanks!

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-Jamie

OK. Here's what I got.

With the trim pot half way up and the effect pot all the way up...

Pin 7: 9.35v
Pin 4: 0v
Pin 2: 2.95v
Pin 3: 3.60v
Pin 6: ~~4v

Now, pins 2 & 3 would shift about .05 or so. Pin 6 actually shifted between 3.4v to 4.2v.

_________________
-Jamie

Anybody got any ideas based on the results I posted yesterday? (i.e., bump )

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-Jamie

Measure the voltage on the north end of the 3M9 resistor. You should see a fluctuating voltage. You should be able to change how fast fluctuates with the speed/rate pot.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Trim pot is half way up.

With speed/rate all the way up, I get fluctuation from 3.9 to 4.0.

With speed/rate all the way down, I get fluctuation from 3.2 to 4.6.

_________________
-Jamie

What voltage range do you get on the south side of the 3M9 resistor? Does the rate of fluctuation change with the speed pot? Are you able to adjust the voltage range (not the rate of fluctuation) with the trimpot?

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

speed/rate pot:
All the way down I get fluctuation between 1.80-2.10
All the way up I get a steady 1.96

trim pot:
The voltage range does adjust on the trim pot. I get 3.35 all the way down to 0.755 all the way up.

_________________
-Jamie

Bumping this after I've posted my last results. Anybody got anything else for me to look at or try? I cannot find anything wrong so I've got to be missing something.

_________________
-Jamie

Did you take voltage readings from IC 1-5? Need to make sure those op amps are passing signal.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

I did not. Just IC 6 and it was what was expected. I can get readings tonight and get back. Am I looking at the same readings as I saw for IC 6?

_________________
-Jamie

In general, you should have 9 volts on pin 7, 0 volts on pin 4, and about 1/2 of pin 7 on pins 2, 3, and 6.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Thanks! I'll check it out tonight and get back to you...

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-Jamie

OK. Everything look good except IC 2 - got weird stuff. Pin 3 climbed to 198 then would drop back down and back up again. I checked it several times to make sure I wasn't doing anything dumb. Pin 4 was 7.44 not 0.

Here's the breakdown:
IC 1
pin 1: 9.38
pin 4: 0
pin 2: 3.52
pin 3: 3.35
pin 6: 3.51

IC 2
pin 1: 9.36
pin 4: 7.44
pin 2: 5.22
pin 3: 0-198 and back again
pin 6: 6.93

IC 3
pin 1: 9.33
pin 4: 0.1
pin 2: 4.43
pin 3: 3.53
pin 6: 1.93

IC 4
pin 1: 5.12
pin 4: 0.1
pin 2: 3.53
pin 3: 3.53
pin 6: 5.12

IC 5
pin 1: 9.31
pin 4: 0.1
pin 2: 3.54
pin 3: 3.53
pin 6: 1.96

_________________
-Jamie

IC2 is probably not passing signal. Try swapping IC1 and IC2, re-taking the voltage readings, and see if the issue moves with the op amp to the IC1 position.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Done. It's still on the IC2. Did not follow the op amp.

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-Jamie

Okay - there is an issue with the IC2 socket, or associated components. It looks to me that pin 4 is the culprit; when ground has a bunch of positive voltage like that , that is usually your issue.

Take out the chip and test for continuity from pin 4 of the socket to the pin 4's on the other ICs. Have a careful look at both sides of the PCB; is the pin 4 solder connection bad? Did the socket pin get bent underneath the socket and not actually go into the PCB pad? Need to find out why you have voltage on pin 4.

Looking at the photo of the bottom of your PCB, it does look like the socket lug for pin 4 is not protruding through the solder.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker