Ground reference issue (?) running Tonebender MKII and Glory Hole with JMK Paralyzer

Wizardofwoz66

Wizardofwoz66

Active member
Hey guys, kind of a weird one. Someone asked me to build them a Tonebender MKII/Morning Glory (Glory Hole) with a parallel blend. I had considered (not enough clearly) that there might be issues since the Tonebender uses the charge pump trick to get -9V/positive ground. Using the JMK Paralyzer for the blend, the Morning glory side works fine but the Tonebender side is dead (I've tested them without the Paralyzer and it works fine). Any thoughts on how to deal with this? Is there a way to even do it? Thanks!

Derek
 
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Couple questions:

• You’re trying to build all three of these into one enclosure, with a shared power supply?
• So, Tonebender and MG connected to the same power jack/supply, and both work?
• But when you add the Paralyzer to the same supply, the Tonebender loses power? Is that right?
 
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pricklyrobot said:
Couple questions:

• You’re trying to build all three of these into one enclosure, with a shared power supply?
• So, Tonebender and MG connected to the same power jack/supply, and both work?
• But when you add the Paralyzer to the same supply, the Tonebender loses power? Is that right?
Click to expand...
  • Yes, all one enclosure for all three. The Paralyzer has two send/returns that I'm going to run the Tonebender and MG through so input -> Paralyzer -> split s/r to both effects -> Paralyzer -> out
  • Yep, both effects work independently through the PPCB test rig, I have the power supply hot and grounds for all three things wired together and alligator clipping them into the power on the test rig and no issues.
  • I don't know that the TB loses power but there's no signal once the Paralyzer is in the chain. I haven't done troubleshooting on the Paralyzer board yet but I'm going down my checklist of things that could be the problem and I feel like this is a more likely issue than one of the few components on that board being bad. No bridges/cold joints etc on the Paralyzer board though from visual inspection.
 
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Trace through your grounds and ensure your PNP style Tonebender has blocking caps on the input and output, as well as from circuit ground to chassis ground (which includes raw 1/4" jacks).
 
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andrewsrea said:
Trace through your grounds and ensure your PNP style Tonebender has blocking caps on the input and output, as well as from circuit ground to chassis ground (which includes raw 1/4" jacks)
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It's the PedalPCB Tone Vendor MKII, it's got an input blocking cap but not output, I think it's beyond that. I guess the big question is how to isolate the ground of the Tone Bender from the Paralyzer/Morning Glory since it's all gotta run off of one power input?
 
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pricklyrobot said:
Patching something other than the TB into that side of the Paralyzer would be an easy way to eliminate the Paralyzer audio path as a potential problem. If you haven’t tried that already.
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I haven't tried this yet, easy enough to try. I think the actual problem is that the grounds are tied together though for all of the stuff, not sure how to power it off one input otherwise though?
 
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Wizardofwoz66 said:
It's the PedalPCB Tone Vendor MKII, it's got an input blocking cap but not output, I think it's beyond that. I guess the big question is how to isolate the ground of the Tone Bender from the Paralyzer/Morning Glory since it's all gotta run off of one power input?
Click to expand...

You shouldn't have to isolate power supplies. For the Tone Vendor MKII: IC1, C7 and C4 should adequately isolate the positive and negative ground circuits.

Since output jacks of many if not most pedals are tied to signal ground via chassis ground, that design has to be sufficient to allow the Tone Vendor to be placed in-line with other pedals without the need for independent supplies. I think your issue may be the JMK Paralyzer.
 
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andrewsrea said:
You shouldn't have to isolate power supplies. For the Tone Vendor MKII: IC1, C7 and C4 should adequately isolate the positive and negative ground circuits.

Since output jacks of many if not most pedals are tied to signal ground via chassis ground, that design has to be sufficient to allow the Tone Vendor to be placed in-line with other pedals without the need for independent supplies. I think your issue may be the JMK Paralyzer.
Click to expand...
Duh lol this was dumb of me to even think, didn't even cross my mind that most effect grounds are tied together lol
 
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This is driving me crazy lol. I've checked continuity through the entire Paralyzer, verified component values, and audio probed it. I lose signal past R6 (will post schematic) and cannot figure out why. No solder bridges etc. I haven't used any of the batch of Paralyzers I built so I can't verify that they work, I tried swapping it for another and still have the same issue so I assume it's something stupid I'm doing, the JMK stuff has always been good in my experience. A few nasty looking joints on the wires from swapping the boards that I'll fix later but electronically they're solid for testing purposes
 

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jwin615 said:
Are you sure a lug of the blend pot isn't contacting the enclosure? That would do it.
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I checked this and no, nothing unintentionally grounded. I ended up swapping the Paralyzer out for a Panner and using that as a clean blend for the MG side and it sounds great so we're just going to roll with that. Has to be something with the Paralyzer boards I built but I can't for the life of me find it lol.
 
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