Brown Betty slowly dying

TSReppe

Active member
Hey Guys!

I’m new on the forum and pretty new to pedal building. I recently(almost) completed a Brown Betty, but it has issues and I’m nor sure how to look for them. Hopefully someone has any advice.

1. The bass control does nothing. This might just be a malfunctioning pot, but If anyone has any other ideas of what I should look into I’m all ears. There is a little bit of a scratching sound when I turn it, but not a lot and there’s nothing happening with the sound.

2. This is a bigger issue. When I fire up the pedal it works perfectly(except that pot ofc). But after playing a while it slowly dies. Almost soujds like a rapidly dying tube. It starts scratching, than falling in and out before it goes total dead. Takes about 10-15 minutes for this to happen. If I unplug the dc power and plug it back in it works great again, for 10-15 minutes. I can’t see any cold solders. On cap was badly soldered, but that has been fixed.

Hope someone can help me out cause I love the sound of the pedal.
 

BuddytheReow

Breadboard Baker
You may have a bad dc jack. Try replacing it.

do you have a dmm to test the bad pot? Also see if it’s shorting out on the board. Do you have dust covers?
 

TSReppe

Active member
You may have a bad dc jack. Try replacing it.

do you have a dmm to test the bad pot? Also see if it’s shorting out on the board. Do you have dust covers?
Hey Man!

thanx for replying. I can def try changing the DC-jack. I’d be really happy if it’s that easy.

now for the noob-reply: I have a dmm, but not sure how I’d test the pot. I have decent soldering skills, but still working on my theoretical knowledge in this field. Dust cover?
 

Jovi Bon Kenobi

Well-known member
I've had power jacks fail but never gradually, they would just intermittently short out. How about some clear photos of the top and bottom of the board and wiring?
 

dlazzarini

Well-known member
Hey Man!

thanx for replying. I can def try changing the DC-jack. I’d be really happy if it’s that easy.

now for the noob-reply: I have a dmm, but not sure how I’d test the pot. I have decent soldering skills, but still working on my theoretical knowledge in this field. Dust cover?
Dust covers are little plastic caps that cover the body of the pot keeping it from shorting to the underside/solder side of the board.
To test your pot, set your dmm to measure resistance. Connect your probes to lugs 1 and 2. Turn the pot and watch for resistance change. You should see it go from zero ohms to somewhere close to the rated resistance of the pot. Also always post clear pics of both sides of the board and all of the off board wiring.
 

BuddytheReow

Breadboard Baker
Dust covers are little plastic caps that cover the body of the pot keeping it from shorting to the underside/solder side of the board.
To test your pot, set your dmm to measure resistance. Connect your probes to lugs 1 and 2. Turn the pot and watch for resistance change. You should see it go from zero ohms to somewhere close to the rated resistance of the pot. Also always post clear pics of both sides of the board and all of the off board wiring.
Also test lugs 2 and 3. For resistance testing, it doesn't matter which color (red or black) goes to each lug. Set your meter one notch above what the pot value should be. For example, my meter goes in increments (2k, 20k, 200k, 2m). If the pot has a value of 100k then set the meter to 200k to test.
 

TSReppe

Active member
Really helpful info guys!

I measured the pot and yeah, it’s not working properly. I’ll get it changed. It showed pretty much the same value clockwise as counterclockwise.

Here are pictures. I know it ain’t pretty, but I can’t see any cold solders or things touching that shouldn’t touch.
 

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zgrav

Well-known member
the measured values on a pot won't change if you are testing the outside terminals. the change is between the middle terminal and each of the outside terminals. so measure the resistance from terminals 1 and 2 when you rotate the shaft, and between 2 and 3.
 

Jovi Bon Kenobi

Well-known member
Once you sort out that pot, I'd definitely second recommendation of insulating the back of the pots from the board for future builds. Of course, dust covers are the best option, but there are other choices...sticking on a rubber foot, a piece of heavy cardstock, etc... If you use electrical tape, one layer is usually not enough or recommended.
Also, welcome to the forum!
Figures 18-22 on this thread show another method for insulating pots.
 

zgrav

Well-known member
have you confirmed the bass control does not work even when the board is not mounted inside the enclosure? if you can test it when it is out of the box, try it with the bass pot lifted up a little off of the board and see if it works then.

going back to the pot that you measured where the resistance did not change when you turned the shaft -- what reading were you getting on your dmm?
 

TSReppe

Active member
have you confirmed the bass control does not work even when the board is not mounted inside the enclosure? if you can test it when it is out of the box, try it with the bass pot lifted up a little off of the board and see if it works then.

going back to the pot that you measured where the resistance did not change when you turned the shaft -- what reading were you getting on your dmm?
No difference outside the enclosure and bent further from the board. Dmm set to 200k it shows about 07.0 either way. The mid pot which is also a rev log 100k shows the same all the way down, but double all the way up measured on 1 and 2. Mirrored measurements if I measure 2 and 3.

But it’s that slowly dying thing that the biggest issue.
 

zgrav

Well-known member
if you can run more than one pedal at a time on the power supply you are using, see if anything funny is going on with a different pedal when you are getting the "slow death" thing going on with your new build. It might be your power supply is struggling at the same time. and when you are getting the "slow death" sound see if your power supply is warm to the touch. I am wondering if you have a short on your pedal that is straining your power supply.
 

TSReppe

Active member
if you can run more than one pedal at a time on the power supply you are using, see if anything funny is going on with a different pedal when you are getting the "slow death" thing going on with your new build. It might be your power supply is struggling at the same time. and when you are getting the "slow death" sound see if your power supply is warm to the touch. I am wondering if you have a short on your pedal that is straining your power supply.
Ok I’ve made some progress. When the dying starts happening I physically touch the solderingspots of C22, then the pedal comes right back to life. Would suppose that means that cap is bad. I’m waiting for the pedal to die again to make the same test with other caps to see if it’s an isolated issue. Unsure how that cap being bad could cause this issue.
 

TSReppe

Active member
Now where getting somewhere :). Good feeling when we make troubleshooting progress
I’ve replaced it and will now have to wait 10-15 minutes and see if the pedal is still alive. It was a high quality wima cap in that position. Annoying if it turns out to be the responsible component.
 
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