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PostPosted: Mon Jan 18, 2021 3:28 pm 
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Hey all,

Sorry, I don't have pics currently. But, I finished the A/B True Bypass Looper. Everything works great. Super clean sound, switches as it should. LEDs also switch. BUT - the LEDs are VERY dim. I tested each with the resistors before starting the build and they were quite bright, now they're so dim. I'm not sure where to start with troubleshooting. Anyone have any ideas.

Again, everything works as it should, just really dim LEDs. So I don't think there should be a grounding issue anywhere.

Of note: I've build quite a few pedals, loopers, PCB boards, etc. I'm not perfect, but they've always worked so I think the build quality is sufficient.

Any advice on where to start troubleshoot would be helpful.

I can upload pics when I get home.
Thanks!


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PostPosted: Mon Jan 18, 2021 9:01 pm 
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I'm wondering if you got the wrong value of current limiting resistors. Can you verify that they are 4k7 (yellow/purple/black/brown/brown)? If you need help with that, a photo would do the trick.

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PostPosted: Mon Jan 18, 2021 9:10 pm 
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They're 4K7. That was my initial thought - that I grabbed the wrong set of resistors but I double checked. I used 4K7s.

I figured it out. It was a grounding issue. In my opinion, the way it is designed in the instructions - the grounding is very poor for the LED circuit. I felt this was the case as I was building it but continued as the instructions state anyway. The sleeves for both the send and returns in both loops A and B are not grounded. I completed these and just ground them back to the DC adapter and everything lit as it should - and as bright as it should. I guess it was poorly grounding through the metal enclosure so the LEDs came on very dimly.

I will fully endorse, I left out the battery snap and used a mono input instead of stereo input hack as the ring was just a disconnect/on/off when using the battery any way - but I can't see any way that would have changed things. I've also scoured the instructions AGAIN and in no where is it instructed to solder off the sleeves of the send and returns back to ground.

Any way, thanks for your help! Got my brain rolling enough to figure this out. I just ran test wires so I'll solder everything up tomorrow or the day after.

sjaustin wrote:
I'm wondering if you got the wrong value of current limiting resistors. Can you verify that they are 4k7 (yellow/purple/black/brown/brown)? If you need help with that, a photo would do the trick.


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PostPosted: Mon Jan 18, 2021 9:20 pm 
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Joined: Mon Jan 18, 2021 3:18 pm
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I also did some trouble shooting - I can just ground EITHER the input or output back to the DC adapter and it works. Every looper I've built, and a few I've designed I always soldered the ground terminals back to the DC adapter. I guess that may have been redundant. I this instance it looks like leaving the battery snap off was my issue. I didn't account for that.

My bad... Live and learn I guress!


sjaustin wrote:
I'm wondering if you got the wrong value of current limiting resistors. Can you verify that they are 4k7 (yellow/purple/black/brown/brown)? If you need help with that, a photo would do the trick.


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PostPosted: Tue Jan 19, 2021 11:51 am 
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meidinad wrote:
I figured it out. It was a grounding issue. In my opinion, the way it is designed in the instructions - the grounding is very poor for the LED circuit. I felt this was the case as I was building it but continued as the instructions state anyway. The sleeves for both the send and returns in both loops A and B are not grounded. I completed these and just ground them back to the DC adapter and everything lit as it should - and as bright as it should. I guess it was poorly grounding through the metal enclosure so the LEDs came on very dimly.

I have never run into an issue with the I/O jack sleeves not grounding through the metal enclosure. About the only way this could reasonably happen is if the enclosure has been so heavily painted/finished inside and out that the metal of the jack sleeve and the enclosure don't make contact. Of course, using a different enclosure made of a non-conductive material would also cause this.

meidinad wrote:
...I left out the battery snap and used a mono input instead of stereo input jack as the ring was just a disconnect/on/off when using the battery any way - but I can't see any way that would have changed things.

meidinad wrote:
I also did some trouble shooting - I can just ground EITHER the input or output back to the DC adapter and it works. Every looper I've built, and a few I've designed I always soldered the ground terminals back to the DC adapter. I guess that may have been redundant. I this instance it looks like leaving the battery snap off was my issue. I didn't account for that.

Your assumption about the function of the stereo input jack with the battery snap is what led to the problem. That's because the ring is the ground connection for both the battery and the DC jack. You were apparently getting some partial degree of grounding for the LED's to light at all, but nowhere what you should have had. When you connected the sleeve of one of the I/O jacks back to the DC jack, that provided the needed ground connection. You'll note that that connection is shown in the top diagram on page 13 of the instructions. When using a mono input jack, that connection just needs to be to the sleeve tab rather than the (non-present) ring tab. You can't just leave it out.

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PostPosted: Tue Jan 19, 2021 12:00 pm 
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Yup, you're right. I figured that out. It was my mistake. I planned to ground that but forgot once I started building. Then when I had a very very faint light, I thought I was getting grounding through the instrument cables - which made no sense to me either. But, my rudimentary experience and limited time didn't let me investigate further.

You're right though, it was my mistake and I left the LED circuit open. I still can't quite figure out why the sleeves remain ungrounded/if there's any benefit (potential noise?) if they were all grounded back to the input or output.

Either way, very cool utility looper. I'm running a fuzz on one size, and a compressor on the other. I don't like to use them both together as the compressor increases the fuzz's noise floor. This is a really easy way to switch between the two. Or cut them out completely if I'd like.

Thanks so much for your help!





duhvoodooman wrote:
meidinad wrote:
I figured it out. It was a grounding issue. In my opinion, the way it is designed in the instructions - the grounding is very poor for the LED circuit. I felt this was the case as I was building it but continued as the instructions state anyway. The sleeves for both the send and returns in both loops A and B are not grounded. I completed these and just ground them back to the DC adapter and everything lit as it should - and as bright as it should. I guess it was poorly grounding through the metal enclosure so the LEDs came on very dimly.

I have never run into an issue with the I/O jack sleeves not grounding through the metal enclosure. About the only way this could reasonably happen is if the enclosure has been so heavily painted/finished inside and out that the metal of the jack sleeve and the enclosure don't make contact. Of course, using a different enclosure made of a non-conductive material would also cause this.

meidinad wrote:
...I left out the battery snap and used a mono input instead of stereo input jack as the ring was just a disconnect/on/off when using the battery any way - but I can't see any way that would have changed things.

meidinad wrote:
I also did some trouble shooting - I can just ground EITHER the input or output back to the DC adapter and it works. Every looper I've built, and a few I've designed I always soldered the ground terminals back to the DC adapter. I guess that may have been redundant. I this instance it looks like leaving the battery snap off was my issue. I didn't account for that.

Your assumption about the function of the stereo input jack with the battery snap is what led to the problem. That's because the ring is the ground connection for both the battery and the DC jack. You were apparently getting some partial degree of grounding for the LED's to light at all, but nowhere what you should have had. When you connected the sleeve of one of the I/O jacks back to the DC jack, that provided the needed ground connection. You'll note that that connection is shown in the top diagram on page 13 of the instructions. When using a mono input jack, that connection just needs to be to the sleeve tab rather than the (non-present) ring tab. You can't just leave it out.


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