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PostPosted: Fri Jan 11, 2019 6:18 pm 
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Howdy! Having an issue with my Crown Jewel: no boost. I have the JFET boost. All the overdrive stuff works. Just the boost is dead. LED comes in and no sound at all.

1st thing: I am unsure how to set the 2 trim pots. The instructions say the middle post should be 9 volts. OK. What does the other meter lead go on? I made the assumption that it goes on one of the two other posts. One gives me the same reading regardless of pot position. The other does change values but I could never quite hit 9 as it would jump from 7 to 12 with the smallest turn.

I did try turning the trim pots while strumming but no sound.

Tomorrow I can take the pedal apart and post pics. Was hoping someone would have something for me to try before I take it apart.

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PostPosted: Fri Jan 11, 2019 6:30 pm 
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Whenever you're probing voltages, the black lead will connect to ground. A screw hole is my favorite spot, if available. With the CJ, the chassis is ground, so the screw hole method works.

You will want to very slowly turn the trimpot, and just get as close to 9v as you can.

If you get the voltages set, and still don't hear anything, pictures will be the next troubleshooting step.

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PostPosted: Fri Jan 11, 2019 9:03 pm 
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Nwkenning wrote:
Whenever you're probing voltages, the black lead will connect to ground. A screw hole is my favorite spot, if available. With the CJ, the chassis is ground, so the screw hole method works.


OK. So it turns out I may not know that much about multimeters. I dropped the black lead in the screw hole for the enclosure. Set the meter to the DC with the V and a solid line and a dashed line over the top. I got a reading of -7.88 on the center post (the one by himself) no matter where I turned the pot. I thought a negative reading was when you have the + and - leads reversed (but that is an assumption). I have an Innova 3320 meter. I also tried the battery tester at 9 volts. Different values (still negative) and they shifted with the turning of the pots but the values would change ~~2 to ~~4 from clockwise to counterclockwise. I also noticed if I changed it to 12V that the numbers changed so I'm assuming that setting it is only for testing batteries.

Oh, and to make sure the grounding was correct I also did the readings with the black lead on the ground for the output jack. Got the same measurements.

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PostPosted: Sat Jan 12, 2019 3:52 am 
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Do you have your probes plugged into the correct meter jacks? The black one goes in the center jack at the bottom of the meter. The red probe goes in the jack on the right just above the CE when measuring voltage.

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PostPosted: Sat Jan 12, 2019 8:06 am 
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Stephen wrote:
Do you have your probes plugged into the correct meter jacks? The black one goes in the center jack at the bottom of the meter. The red probe goes in the jack on the right just above the CE when measuring voltage.

Yep. I do.


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PostPosted: Sat Jan 12, 2019 4:24 pm 
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I didn’t desolder anything. Did my best to get up uber pots. If I need to remove a pot or switch, let me know.


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PostPosted: Sat Jan 12, 2019 4:30 pm 
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More pics...


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PostPosted: Sat Jan 12, 2019 4:32 pm 
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And more pics...


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PostPosted: Sat Jan 12, 2019 4:33 pm 
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And the last...


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PostPosted: Mon Jan 14, 2019 12:19 pm 
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The build looks excellent. Nice soldering. I do however, notice that one of the wires looks like it has frayed and come loose, perhaps from moving it around while trouble shooting.

Assuming that that has nothing to do with your boost channel problem, you should begin by verifying the boost channel signal path. You do this by simply placing a jumper wire between the "I" and "O" sockets of the boost module socket. If everything works, you'll just have a secondary volume control for your unaffected guitar signal.

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PostPosted: Mon Jan 14, 2019 12:25 pm 
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byoc wrote:
Assuming that that has nothing to do with your boost channel problem, you should begin by verifying the boost channel signal path. You do this by simply placing a jumper wire between the "I" and "O" sockets of the boost module socket. If everything works, you'll just have a secondary volume control for your unaffected guitar signal.

...and you'll know that the problem is on the module board.

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PostPosted: Mon Jan 14, 2019 10:31 pm 
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byoc wrote:
The build looks excellent. Nice soldering. I do however, notice that one of the wires looks like it has frayed and come loose, perhaps from moving it around while trouble shooting.

I popped the wire man-handling it while removing it from the case. Didn't see it until after I snapped the pic. Fixed now.

byoc wrote:
Assuming that that has nothing to do with your boost channel problem, you should begin by verifying the boost channel signal path. You do this by simply placing a jumper wire between the "I" and "O" sockets of the boost module socket. If everything works, you'll just have a secondary volume control for your unaffected guitar signal.

Placed a jumper between the I and O sockets (see pic). I do have sound when the boost is engaged now and I can control the volume using the boost pot.


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PostPosted: Tue Jan 15, 2019 11:14 am 
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jajoyner wrote:
Placed a jumper between the I and O sockets (see pic). I do have sound when the boost is engaged now and I can control the volume using the boost pot.

OK, then we know the problem is on the boost module itself.

Can you get close-up shots of the flat faces of the two JFET's so that the labeling can be read? BYOC received a shipment of counterfeit 2N5457 JFETs recently. The JFET boost module for the Crown Jewel uses 2N5458's, a different JFET, but I still think this would be worth checking.

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PostPosted: Tue Jan 15, 2019 11:38 am 
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duhvoodooman wrote:
Can you get close-up shots of the flat faces of the two JFET's so that the labeling can be read?

I had this shot on my phone. Can get better pics when home tonight.


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PostPosted: Tue Jan 15, 2019 3:12 pm 
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OK. I have better pics of both transistors...


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PostPosted: Thu Jan 17, 2019 12:12 pm 
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duhvoodooman wrote:
Can you get close-up shots of the flat faces of the two JFET's so that the labeling can be read? BYOC received a shipment of counterfeit 2N5457 JFETs recently. The JFET boost module for the Crown Jewel uses 2N5458's, a different JFET, but I still think this would be worth checking.


Any update on this since I posted pics? I’d like to resolve this as soon as possible. Thanks!

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PostPosted: Thu Jan 17, 2019 12:44 pm 
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Have you tried reflowing your solder joints. What voltage are you getting on the drain of each JFET? You're shooting for 9v. Are you able to adjust close to that with the trimpots?

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PostPosted: Thu Jan 17, 2019 12:52 pm 
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That batch tests as actual JFETs, I went through all the JFET module packs and tested them all. There were none that tested as BJTs, which mean that the batch is genuine. It's possible you got a bad one, but more on that later.

One thing I have noticed through all this is that the right trimpot in all your pictures hasn't changed position at all. You said in your original post that one gives you the same voltage regardless of position of the trimpot, that shouldn't be happening, the voltage should change regardless since it's a variable resistor from the +18v rail. Can you do us a favor and do a resistance test on the trimpot that has no effect on the voltage? It doesn't have to be precise, we're just looking for it to change one way or another. Give us your readings.

All that said, I have a pair of JFETs here with your name on it, or a new trimpot if it's shown to be wonky. Before we throw parts at it, I'd like to figure the trimpot-voltage thing first.

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PostPosted: Thu Jan 17, 2019 10:00 pm 
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Nwkenning wrote:
Can you do us a favor and do a resistance test on the trimpot that has no effect on the voltage? It doesn't have to be precise, we're just looking for it to change one way or another. Give us your readings.

I will do so tomorrow and take pics of the results. Is this the correct setting to test voltage? Wanna make sure I’m doing this properly...


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PostPosted: Thu Jan 17, 2019 10:16 pm 
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No, it’s the ohm symbol, two clicks to the right of your circled setting (which is DC voltage).

You should look up tutorials on YouTube on using a multimeter. Specifically, how to test resistance and testing the resistance of a potentiometer.

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PostPosted: Thu Jan 17, 2019 10:28 pm 
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Yes, that's the correct setting for measuring DC voltage....but that's not what Nick suggested that you do. He wants you to check the resistance (the white omega symbol) across the ineffective trimpot to see if it varies as you turn it. You'll need to put one probe on one of the outside legs and the other probe on the other outside leg, and then measure the resistance at at least three points (the two extremes and the midpoint) of the trimpot sweep. If the pot is working, it should be nearly 0 ohms at one extreme, close to 25 Kohms at the other extreme, and around 12 - 13 Kohms at the midpoint. Take these resistance measurements with the power source disconnected from the pedal.

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PostPosted: Thu Jan 17, 2019 10:37 pm 
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EDIT: Yeah, what DVM said!

Yeah. That's for DC voltage, black probe to ground (screw hole, or you can try to chopstick it with another ground location), red probe to the middle lug of each trim pot. You should see a change in voltage through the sweep, try to set them close to 9v, and see if it works. If you can set both of them to around 9v, and it still doesn't work, let us know.

If you still can't get the trim pot you mentioned earlier to change the voltage, set your meter to the omega symbol (Stargate looking symbol) to do a resistance test. You will see results in ohms. Since it's an auto range meter, it might include suffixes like K or M. The trim pots are 25k, so you should read between 0 and 25k.

Do this with the module installed, but with the pedal unplugged from power. Place one probe on the middle leg, and the other on one of the outer legs. It doesn't really matter which, so long as it's between the middle and one of the outer legs. Test it through the sweep, you don't have to be super precise though, you can just turn them a little and test, turn a little and test. If the resistance changes, it's probably just fine. Like I said before, you might not read those exact numbers because you're testing it in-circuit, but the resistance should still change.

If the resistance doesn't change, take the module out and repeat the test. If the resistance changes with the module out of the enclosure, take the main board out and make sure your header sockets are soldered properly, no shorts etc. If you still don't have a change in resistance, let us know.

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