Build Your Own Clone Message Board

To be clear, are you saying that when you hold down the tap button, the LED does not flash and the delay time does not reset to the position of the delay knob (also known as 'Morgan's Mod')?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

It is part of the stock build. I suspect your chip was not quite programmed properly. Email byoc sales, explain the problem, and they should send you a new controller chip.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

That distortion doesn't sound like the good kind. Rather ugly, hard to believe it could be right.

If you turn down the guitar volume a bit lower can you get the distortion to go away, or is it pretty independent of guitar signal level?

Do you have a signal tracer?

Before going too much further with signal testing, it looks like there might be some marginal solder joints from looking at the PCB photo you posted. Also, looks like some of the component leads on the bottom or solder side of the PCB are sticking out a bit longer than would be ideal.

Therefore, may I ask if you tried reheating or reflowing all the solder joints yet? If not, I believe there are instructions for how to do that somewhere here in the troubleshooting section of the forum.

Once you are sure that stuff is good, it looks like signal flow testing with an audio probe would proceed as follows:
IC1b-7
IC2b-10
IC3-14
IC4-14
IC2a-6
IC1a-1

In particular, IC1 is a compander chip. It compresses the signal from your guitar before sending it to the delay chips. IC2b is the compressor, and IC2a is the expander, which is used to restore the volume dynamics of, or un-compress, the signal that was previously compressed by IC2b.

IC3 and IC4 are the delay chips.

The idea would be to probe the circuits going through the above test points and see where the distortion first appears. Somewhere around that point in the circuit would most likely be where the problem is and more careful inspection of it could then follow.

This doesn't sound that far off to me - it sounds like the clip is played 100% wet with a longish delay time. How long do you have the delay time set in this clip? Have you had any other pedals with a PT2399 chip? These are lofi digital echo chips. When you push the delay time to over about 600ms (on either chip), you will start to get this ugly, digital hash riding on top of your delayed signal. That's just a part of this chip. It's really only noticeable when you are playing with a longer delay time and when the delay mix is very high. When the delay time is shorter and the mix is set at a more 'traditional' level, these chips should sound good, like a classic analog delay.

Does the distortion cleanup somewhat when you lower delay time? If you set your mix knob for a more typical ratio (~10:00) is the distortion still apparent?

FYI - the 100% wet signal is always going to sound pretty funky because it also goes through the compander circuit. Keep in mind that these circuits are meant to have some dry signal mixed in to sound 'right'.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Exactly the same thoughts that I had when listening to the clip. A 100% wet signal with a long delay time just brings out the worst in the PT2399.

P.S. Digital Hash is a good name for a band....

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“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

That is an ugly A. That actually sounds like compander clipping to me, not digital clipping from the PT. You might resolder the compander components and reseat the chip in the socket.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

IC1-7 is the output of the 1st opamp. You might use your scope to measure the voltage from your guitar, or even better find a fixed amplitude signal source such as your PC sound card, and use that to provide a test signal. A guitar tuner or metronome that has a tuning pitch reference output to a headphone jack could also work. Just wire up a cable from the headphone out to the pedal input.

Anyway, guitar or other signal comes in the input jack, and goes through Q1 and Q2. Signal level at emitter of Q2 should be about the same as guitar input signal level at the input jack. It should obviously be not too many volts, with 1 volt or less (peak to peak) on the scope as probably being reasonable.

There is some filtering going in in the 1st opamp stage that follows Q2, but it nominally has a gain of about 1 for most guitar frequencies, which means the voltage at pin 7 should be about the same as the voltage at Q2 emitter. If not, probably wise to check all the resistors and capacitors connected to IC1b on the schematic, and thereabouts. Solder joints around there too. Since you reported high signal level and distortion at pin 7, seems likely you will find something amiss in that area. If not, we can keep working through other parts of the circuit.

One thing that is a little puzzling is that you report different symptoms at IC1-7 depending on whether or not the effect is engaged, but the schematic shows that the signal passes though IC1-7 either way. If that is correct, there could be some problem with one or more of the FET switches, and/or with the power supply.

Okay, understood. However, the basic process I would use for determining where and why there is distortion is still the same.
I would put a stable signal into the pedal, turn the pedal on, and observe the signal as it makes it's way through the circuitry (using an oscilloscope to measure, and referring to the schematic to help understand intended circuit operation).

Using an audio probe can work too, but an oscilloscope is usually preferable because it can measure voltages and visualize changing wave shapes. That is to say, it provides more information than an audio probe does.

One main difference when using an audio probe is that if you hear distortion that you don't think should be there, you may need to turn down the input signal level to see if the circuity is being over driven and that is the cause of distortion. Or you may need to turn up the signal level to see what that does. Also, if the audio probe output is connected to the input of a guitar amp, its necessary to make sure it isn't the guitar amp that is distorting.

However, the same kinds of things might be needed when using an oscilloscope at times. Sometimes changing the input signal or turning the pedal's knobs can provide useful information about a problem.

Anyway, the way I usually troubleshoot these things is by observing signal flow as much as possible. Other people may have their preferred methods that work for them. Sometimes just checking for the most common problems is the most efficient way to get something fixed. However, in your particular case here, other than checking parts and solder connections, and maybe swapping ICs, the easy fixes seem to be mostly ruled out. Once the easy fixes have been tried and the problem persists, getting analytical and systematic is often appropriate if equipment is available to do it. Mostly that means having a DVM, oscilloscope, signal generator, and some technical understanding of how the circuit should be working. Would you agree we seem to be getting to that point? If so, probably time to get out the scope and start measuring.

Hang on, something is not right here and I think I misunderstood an earlier post.

You seem to be reporting that pin 7 of IC1 is dirty at all times. Is that correct?

IC1 p7 has signal running through it in bypass. Do you have distortion in bypass? Distortion with the mix set to 100% dry? From your clip, it sounded like there was no distortion in the dry mix, which would mean no distortion in bypass and no distortion from IC1 p7.

Please verify that you are not mixing up pin 1 with pin 7. Pin 7 is at the input and pin 1 is post delay mix. If you don't have distortion in bypass or with 100% dry, you should not have any distortion on pin 7. Pin 1 has both wet and dry signal. If the distortion is coming from the delay line, pin 1 should be clean at 100% dry and dirty at 100% wet.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Is IC1-1 clean in effect mode with mix set to 100% dry? I.e. Only distorted when delay is mixed in?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker