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PostPosted: Thu May 07, 2020 3:55 pm 
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duhvoodooman wrote:
The one on the inside looks good, but the voltage at the top of the outside one is very low. I see 10.8V on mine there (this is with the pedal in bypass). Try adjusting the Depth Symmetry trimpot until you get somewhere in the 10 - 11V range there and see how the pedal behaves then.


I took those readings with the effect on. Does that make a difference?

Also, I've adjusted the Depth Symmetry pot through its full range, and the signal output is sporadic and glitchy (as heard in that clip in my earlier comment).


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PostPosted: Thu May 07, 2020 5:10 pm 
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In the audio clip I linked earlier in the thread, I was adjusting the Depth Symmetry pot through its full range. The audio cuts in and out and when signal passes through, it's low volume and distorted. That audio was recorded after I resoldered all the points (no audible change from before). I haven't changed anything since then.


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PostPosted: Thu May 07, 2020 8:06 pm 
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MojaveJohnson wrote:
duhvoodooman wrote:
The one on the inside looks good, but the voltage at the top of the outside one is very low. I see 10.8V on mine there (this is with the pedal in bypass). Try adjusting the Depth Symmetry trimpot until you get somewhere in the 10 - 11V range there and see how the pedal behaves then.


I took those readings with the effect on. Does that make a difference?

Yeah, it does, because that connects the LFO circuit and draws variable voltage at that point. So the voltage drops substantially and fluctuates; mine drops from a steady 10.8V down to 4.1 - 4.9V.

MojaveJohnson wrote:
...I've adjusted the Depth Symmetry pot through its full range, and the signal output is sporadic and glitchy (as heard in that clip in my earlier comment).

Based on this described behavior, I'm suspecting that you may have a bad Depth Symmetry trimpot, as long as you're sure that the solder joints on the three pot legs are solid. If so, contact sales@buildyourownclone.com and inform them that you received a faulty 100K trimpot in your Brownface Trem kit. They'll get a replacement out to you at no charge.

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PostPosted: Thu May 07, 2020 8:32 pm 
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duhvoodooman wrote:
MojaveJohnson wrote:
duhvoodooman wrote:
The one on the inside looks good, but the voltage at the top of the outside one is very low. I see 10.8V on mine there (this is with the pedal in bypass). Try adjusting the Depth Symmetry trimpot until you get somewhere in the 10 - 11V range there and see how the pedal behaves then.


I took those readings with the effect on. Does that make a difference?

Yeah, it does, because that connects the LFO circuit and draws variable voltage at that point. So the voltage drops substantially and fluctuates; mine drops from a steady 10.8V down to 4.1 - 4.9V.

MojaveJohnson wrote:
...I've adjusted the Depth Symmetry pot through its full range, and the signal output is sporadic and glitchy (as heard in that clip in my earlier comment).

Based on this described behavior, I'm suspecting that you may have a bad Depth Symmetry trimpot, as long as you're sure that the solder joints on the three pot legs are solid. If so, contact sales@buildyourownclone.com and inform them that you received a faulty 100K trimpot in your Brownface Trem kit. They'll get a replacement out to you at no charge.


Thanks, duhvoodooman! Like I said, I had already resoldered all the points, but I'll reverify the ones on that pot before emailing Keith. I have a can of Deoxit D5 in my guitar repair tools. Should I try a little of that on the pot first?


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PostPosted: Thu May 07, 2020 8:35 pm 
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You can try a shot of Deoxit--can't hurt, but I'll be surprised if it helps. But I've been surprised around here before! :roll: :mrgreen:

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PostPosted: Fri May 08, 2020 10:29 am 
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duhvoodooman wrote:
You can try a shot of Deoxit--can't hurt, but I'll be surprised if it helps. But I've been surprised around here before! :roll: :mrgreen:


The Deoxit made the pot smoother, but there was no change in audio signal. I reverified the solder points, and they're all good and shiny. Just emailed Keith. Thanks for all the help!


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PostPosted: Fri May 08, 2020 10:50 am 
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Hopefully the new trimpot takes care of the issue. But if it doesn't, then I would strongly suggest that you pick up a SIGNAL TESTER (or make one yourself--it's a very simple device). This will allow you to trace out the signal path in the pedal and pinpoint where the dropout is occurring. We can help you with that process, if it becomes necessary.

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PostPosted: Fri May 08, 2020 2:26 pm 
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duhvoodooman wrote:
Hopefully the new trimpot takes care of the issue. But if it doesn't, then I would strongly suggest that you pick up a SIGNAL TESTER (or make one yourself--it's a very simple device). This will allow you to trace out the signal path in the pedal and pinpoint where the dropout is occurring. We can help you with that process, if it becomes necessary.


Thanks! I'll let you know. In the mean time, I have several other projects I'm working on - a resto-mod on a '70's Explorer, some pot/cap changes on a few other guitars, and working on demos for about 2 dozen songs in various stages of incompletion...

The G.A.S. is strong with this one...


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PostPosted: Mon May 18, 2020 3:21 pm 
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OK, I got the replacement pot in this morning, and swapped it out... That wasn't it. I'm getting exactly the same output. :/ Is the signal tester for continuity? Can I use a multimeter?

In the mean time, I ordered, received, and successfully built the Lazy Sprocket pedal kit, and it works fine.


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PostPosted: Tue May 19, 2020 3:28 am 
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A signal probe allows you to audibly hear the signal as it travels thru the circuit. A multimeter is used to measure electrical values and to check continuity.

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PostPosted: Tue May 19, 2020 12:10 pm 
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Stephen wrote:
A signal probe allows you to audibly hear the signal as it travels thru the circuit. A multimeter is used to measure electrical values and to check continuity.


Thanks for the clarification. :D


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PostPosted: Tue May 26, 2020 8:18 pm 
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duhvoodooman wrote:
Hopefully the new trimpot takes care of the issue. But if it doesn't, then I would strongly suggest that you pick up a SIGNAL TESTER (or make one yourself--it's a very simple device). This will allow you to trace out the signal path in the pedal and pinpoint where the dropout is occurring. We can help you with that process, if it becomes necessary.


OK, I got my signal tester. I need some guidance on how to use it and what to look for. Again, I appreciate all the help!


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PostPosted: Wed May 27, 2020 10:29 am 
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Follow the schematic and listen to the active components in the signal path. I would do this with the depth knob all the way down.

Start at the input jack > switch lug 5 > Q1 gate > middle lug of the vol trim pot (adjust the trimmer to make sure it adjusts input vol) > gates of Q2 and Q3 > switch lug 7

http://byocelectronics.com/brownfaceschematic.pdf

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PostPosted: Wed May 27, 2020 11:17 am 
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MojaveJohnson wrote:
OK, I got my signal tester. I need some guidance on how to use it and what to look for. Again, I appreciate all the help!

Some additional details to supplement Morgan's post:

First, it helps to understand what purpose this device serves: think of it as a "movable output jack." It allows you to connect any point in the circuit to your amp or other output device and hear the audio signal that's present at that point.

To use it, connect your guitar (or other audio source) to the input jack of the pedal and connect your power source, but do NOT connect your amp/output device to the output jack. Instead, connect that cable to the 1/4" jack of the signal tester. Next, you want to affix the alligator clip of the tester to a ground point on the pedal--I usually use the sleeve solder tab of the input jack for this purpose. Be sure that you have a good, firm connection with the alligator clip, since the tester won't work if the black wire isn't grounded. Be sure your amp/output device is powered and set to go and engage the pedal footswitch. Set the control pots appropriately for the specific pedal you're testing.

To test, you need to hold the red probe of the tester against whatever point in the circuit that you wish to test for the presence of audio signal and then pluck one of your guitar's strings, unless you're using some kind of constant signal generator. What you want to focus on is the main signal path through the pedal circuit, which you determine from the pedal circuit schematic, as Morgan mentioned.

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PostPosted: Sat May 30, 2020 1:14 pm 
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Thanks for translating Morgan's comment, duhvoodooman! :D Once I got my signal tester assembled, I tested it on the input jack of the pedal, since that's essentially the same as the cable end. Good signal. Next I followed the wire to the switch and tested the signal at lugs 4 (good), 9 (good), and 5 (good). Then I tested the 5 hole on the PCB (good). Then I got lost.

I don't know how to read a schematic, but I tried to figure out the signal path. :/ R1, R2, and R3 gave me a good signal. I don't know what Q1 is, but when I tested the 2N5458, I got that same bad signal from pins 1 and 7, so I'm assuming the problem is either Q1 or the chip (though, you said the voltage looked good on the chip). I hope I did that right.


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PostPosted: Sat Jun 06, 2020 10:00 pm 
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Anyone there?


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PostPosted: Sun Jun 07, 2020 4:39 pm 
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Q1 through Q3 refer to the 3 2N5458 jFET transistors. The 8 pin chip does not carry and signal and you don't signal test that. You need to use the Google to look up the jFET pinouts. You can see below which pin the gate is:
Image

Morgan wrote:
Follow the schematic and listen to the active components in the signal path. I would do this with the depth knob all the way down.

Start at the input jack > switch lug 5 > Q1 gate > middle lug of the vol trim pot (adjust the trimmer to make sure it adjusts input vol) > gates of Q2 and Q3 > switch lug 7

http://byocelectronics.com/brownfaceschematic.pdf

So test all of the 2N5458 gates, test the middle lug of the trim pot, and switch lug 7.

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PostPosted: Fri Jun 12, 2020 1:35 pm 
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Thanks, Morgan! I checked the gates on the 3 2N5458's. The one in the center of the PCB (next to the 103 cap) had no oscillation. The one on the edge of the PCB oscillated cleanly. The one directly between the second 2N5458 and the Level pot sounded dirty as hell.


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PostPosted: Tue Jun 16, 2020 10:39 am 
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It sounds like the issue is isolated to Q3 (center), but we should try to confirm. Your earlier symptoms seemed to indicate volume issues along with the cutting in and out. To Q1 (left side) and Q2 (edge of pcb) have sufficient volume? Do they sound healthy?

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PostPosted: Tue Jun 16, 2020 10:50 am 
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Thanks, Morgan. Since I'm not really sure which 1, 2, and 3 are, I labeled what each is doing.


Attachments:
Brownface Tremolo assembled 1.jpg
Brownface Tremolo assembled 1.jpg [ 922.57 KiB | Viewed 773 times ]
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PostPosted: Tue Jun 16, 2020 11:34 am 
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The 5458 on the left is Q1. The 5458 in the middle is is Q3. And the 5458 on the right is Q2.

Q1 is your input buffer and it's also a volume boost. So you shouldn't hear any modulation at the DRAIN of Q1. But it should be very loud and clean (no distortion).

Q3 is the low pass modulation. You shouldn't hear any "harmonic" tremolo at the DRAIN of Q3. You should hear just regular tremolo and the signal should be devoid of all high frequencies.

Q2 is the high pass modulation. You should observe the same behavior as Q3, but the signal should be devoid of all low frequencies.

Your problem seems to be at Q3. If it's distorted and crackly, that most likely suggests that it's not being biased correctly. If it's not modulating at all, it's likely not getting the LFO signal. This could be a problem at R6 or R8. But it's probably something between the output of IC1a and Q6. Q6 is the 3904 that's farthest to the left. Do you see a fluctuating voltage at the BASE (middle leg) of Q6?

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PostPosted: Wed Jun 17, 2020 9:21 am 
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byoc wrote:
The 5458 on the left is Q1. The 5458 in the middle is is Q3. And the 5458 on the right is Q2.

Q1 is your input buffer and it's also a volume boost. So you shouldn't hear any modulation at the DRAIN of Q1. But it should be very loud and clean (no distortion).

Q3 is the low pass modulation. You shouldn't hear any "harmonic" tremolo at the DRAIN of Q3. You should hear just regular tremolo and the signal should be devoid of all high frequencies.

Q2 is the high pass modulation. You should observe the same behavior as Q3, but the signal should be devoid of all low frequencies.

Your problem seems to be at Q3. If it's distorted and crackly, that most likely suggests that it's not being biased correctly. If it's not modulating at all, it's likely not getting the LFO signal. This could be a problem at R6 or R8. But it's probably something between the output of IC1a and Q6. Q6 is the 3904 that's farthest to the left. Do you see a fluctuating voltage at the BASE (middle leg) of Q6?


The base of Q6 fluctuates between 2.85 and 3.23.

The audio signal at Q3 is the same as at the output jack. Here's the audio again:

https://soundcloud.com/tito-jimenez-3/new-recording-17


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PostPosted: Wed Jun 17, 2020 11:12 am 
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It sounds like the problem is with the LFO. It sounds very square wave with an extremely asymmetrical duty cycle. It should be a fairly even sine wave. And Q2 and Q3 can't bias correctly without the correct LFO signal.

When you listen to the DRAIN of Q1 with the audio probe, what do you hear?

When you listen to the DRAIN of Q2 with the audio probe, what do you hear?

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PostPosted: Wed Jun 17, 2020 3:37 pm 
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byoc wrote:
It sounds like the problem is with the LFO. It sounds very square wave with an extremely asymmetrical duty cycle. It should be a fairly even sine wave. And Q2 and Q3 can't bias correctly without the correct LFO signal.

When you listen to the DRAIN of Q1 with the audio probe, what do you hear?

When you listen to the DRAIN of Q2 with the audio probe, what do you hear?


The DRAIN from Q3 oscillates cleanly.

The DRAIN from Q2 sounds like the clip I shared on the previous comment.


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PostPosted: Wed Jun 17, 2020 5:18 pm 
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Please me more descriptive about Q3. Does it sound like a normal tremolo? Is the waveform smooth or is it choppy like Q2? Are you getting a good volume level out of it? Try pulling one of the leg from C7 from the PCB. This will disconnect the signal from Q2. You said the output sounds like Q2. I'm curious is the output changes is you take the signal from Q2 out of the mix.

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