Monarch accidentally received 18v

D

dlazzarini

Well-known member
I just finished the Monarch. When I first started playing with it it seemed pretty normal but as time went by it started getting really farty no matter where the settings were. The harder you chug the fartier it gets. I then discovered that I had it plugged in to the 18v slot on my power supply. My caps are all more than adequate and I believe the 4580 and the j201’s can handle it. Is there anything else I. There that I may have damaged?
 
18V won't hurt that circuit. My best guess is a bad solder joint has reared it's ugly head. Measure the voltages on Q2-D, Q4-D and IC1-7. And do some visual inspection. Stress points are where the switches and pots are soldered into the board. Any misalignment can lead to cracks in the solder. If you used sockets, check them for loose parts.
 
I was hoping you would pop in. I went back over every solder joint. Nothing unusual in the visual inspection. Q2-D=8.98v, Q4-D=8.97v, IC1-7=4.58v. I will mention that these are new production j201’s from Mouser. I’ve also tried other op amps. Still pretty farty/sputtery most prominent on the lower register chugs. Very present with active Fishman Fluence’s. Much more subtle with passives.
 
My bad, I meant to type Q1-D & Q3-D. While you're at it, check Q1-S & Q3-S. It's possible for JFETs to be in spec per the datasheet and not work in a particular circuit.

IC1 voltage is good.
 
music6000 said:
Have you checked the Footswitch, I have experienced the farting out with dodgy contacts?
Click to expand...
I have not other than checking the solder joints and continuity checks. I will give it the once over again. What exactly do you mean by “dodgy contacts” and what exactly do you check?
 
Just Click the switch On & Off repeatedly to see if there is any change to the output of the pedal.
3PDT Footswitch is the Number 1 failure in pedals!
 
Will try it out tomorrow. This is my first pedal using j201’s. Don’t these normally have a bias adjustment? Could it be possible that one or more of the jfet’s aren’t being biased correctly by one of the fixed resistor’s?
 
dlazzarini said:
Will try it out tomorrow. This is my first pedal using j201’s. Don’t these normally have a bias adjustment? Could it be possible that one or more of the jfet’s aren’t being biased correctly by one of the fixed resistor’s?
Click to expand...
The only issue is your Pedal was working Good & then started going Bad, so no biasing would help you with that!
 
Problem is that I’m not 100% positive that that it was playing fine in the beginning. I’m wondering if I may have not noticed it right away. It’s only while I’m playing in the low registers on the E string, but it’s kind of subtle until you change your pick attack. Really gets farty with hard picking to the point it sounds like it’s right on the edge of cutting out. I also used it first with passive pickups. It’s a lot worse with the fluence’s
 
Are these the Interfet J201's that you purchased?
With this Muamp type of circuit, you don't need to bias like other Jfet circuits with Trimmers.
Can you show a good photo of your PCB & Components for a second set of eyes.
 
music6000 said:
Are these the Interfet J201's that you purchased?
With this Muamp type of circuit, you don't need to bias like other Jfet circuits with Trimmers.
Can you show a good photo of your PCB & Components for a second set of eyes.
Click to expand...
They are Interfet from Mouser. All I have currently on my phone is the component side of the board. I’ll post it again. I’m pretty proficient at soldering but I did reflow. I do have a dust cap on the pot under the board. The pedal behaves the same outside of the enclosure as well.
 

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I checked all your Resistors & Caps that i can read, All looks Good!
Check for Continuity on you toggle switches that Middle & Bottom pads only connect when toggles are UP.
Middle & Top pads only connect when Toggles are Down.
Could be those crazy pin Interfets!
 
music6000 said:
I checked all your Resistors & Caps that i can read, All looks Good!
Check for Continuity on you toggle switches that Middle & Bottom pads only connect when toggles are UP.
Middle & Top pads only connect when Toggles are Down.
Could be those crazy pin Interfets!
Click to expand...
Thank you for taking the time to look it over. I’ll check them toggles after work. I’m starting to question those interfets myself. I knew the gremlins would catch up to me sooner or later. I’m about 30 builds into this hobby without one hiccup. Now back to back to back pedals. I’ve got the Emu Amp Sim sitting on the bench as well
 
Hey there Chuck and Music6000. I swapped out all 5 of my Jfet’s. It got rid of MOST but not all of the farty sound when picking hard but something’s still not right. I’ve heard this pedal and mine’s missing a whole lot of distortion. Here’s all of my voltages. Maybe you guys can help steer me in the right direction. I’ve checked and reflowed all joints, switches etc.
Q1-D=4.61, S=0.48, G=0
Q2-D=8.96, S=4.61, G=4.27
Q3-D=4.64, S=0.19, G=0
Q4-D=8.96, S=4.64, G=4.24
Q5-D=6.21, S=0.22, G=0
IC pins
1=8.43
2=8.42
3=0
4=0
5=4.31
6=4.57
7=7.73
8=8.96
 
dlazzarini said:
Hey there Chuck and Music6000. I swapped out all 5 of my Jfet’s. It got rid of MOST but not all of the farty sound when picking hard but something’s still not right. I’ve heard this pedal and mine’s missing a whole lot of distortion. Here’s all of my voltages. Maybe you guys can help steer me in the right direction. I’ve checked and reflowed all joints, switches etc.
Q1-D=4.61, S=0.48, G=0 OK
Q2-D=8.96, S=4.61, G=4.27 OK
Q3-D=4.64, S=0.19, G=0 OK
Q4-D=8.96, S=4.64, G=4.24 OK
Q5-D=6.21, S=0.22, G=0 OK
IC pins
1=8.43 WTF?
2=8.42 WTF?
3=0 OK
4=0 OK
5=4.31 OK
6=4.57 OK
7=7.73 BAD!
8=8.96 OK
Click to expand...

Something is wrong with IC1. Possible causes:
Bent lead, solder short, leaky C19, bad IC.

One other possibility: design error. the JRC 4580 datasheet does not say what happens when either input is connected to the negative rail (ground). Some opamps go haywire if you do that. I'd think Brian Wampler would know better if that was a problem, but, it doesn't hurt to check. Bend pin 3 up, temp jumper it to Vref and check IC1-7. If IC1-7 is near Vref (4.5V) then that was the problem.
 
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