Buff’n’Blend problem (solved)

[Anonymous]

Hello everyone,

I’m stuck with my first project. I’ve started the project by assembling it outside an enclosure and everything worked perfect – therefore I would assume that the onboard components were working and placed/oriented correctly. However, when I tried to put it in an enclosure, things started to get worse: First, the wet signal was completely gone, but that turned out to be a shaky solder joint which I could fix by resoldering the wires going to the send/return jacks (I want to use the Buff n Blend ‘standalone’ as a loop pedal with blend function). However, now I have some signal when the pedal is engaged, but it sounds quite bad:

• In bypass I get a perfectly good signal, therefore I assume that input/output jacks and 3DPT switch are ok.
• When turning the effect on the LED light turns green, therefore the power supply seems to be ok as well (I also tried a different PSU but also nothing changes).
• However, after ~1 second the tone deteriorates (I would describe it as thin, distorted in a ‘farty’ way and gated). Everytime I plug in the power supply again the same thing happens – nearly proper signal in the beginning and then it gets weak/distorted. I tried to resolder all wires in order to rule out bad connections but nothing changes. I also tried to scratch the spaces between the pads gently with a knive to remove possible solder bridges caused by flux, but nothing changes.
• Unfortunately I do not yet have a multimeter yet (I ordered one online, but I guess it will take a few days until I receive it, I will then post values if needed; I think i will also build an audio probe), however I’d still like to ask you for your support because I’ve entcountered something strange which could narrow down possible root causes: Oddly, when I touch the tip and sleeve lugs of the send jack, the signal becomes strong and clear, blending in the wet signal seems to work perfectly again. Does that indicate maybe some kind of grounding issue (which would mean that the onbard components are still ok and I have another look at the wiring)? Or did I possibly fry some heat sensitve components (I have to admit that I forgot to socket the MPF102, so that would be my next guess)?

Thank you very much in advance, your advice is highly appreciated!

Best,
Patrick

[Anonymous]

Dear all,

I forgot to mention one (maybe crucial) aspect: Before putting the PCB into the enclosure I’ve also desoldered the LED and attached wires in order to move the LED to another place in the enclosure – the LED is working flawlessly after reattaching to the PCB, however since the LED is located directly next to C1 I wonder if I might have messed up something with the capacitor; could that maybe have caused a biasing issue?

Thanks and best regards

Patrick

[Barry]

Not much to go on here.

The biggest clue is that you had it working then as a result of moving it to an enclosure it is not working.

That would indicate that there is a loose wire, short, bad solder joint etc..

Did you have a biasing issue when you initially tested it?

Unfortunately these are the kind of things that are hard for us to diagnose with no pictures or voltages.

I would re-flow all solder joints on and off board. Re-check all wiring and check for continuity with a DMM and finally if that does not work out we will need clear photos of both sides of the board as well as voltages of your transistor.

[Anonymous]

Dear Barry,

thank you very much for your response. Unfortunately I haven’t received yet the multimeter that I’ve ordered, but (seemingly) my problem was solved by swapping out C1 (I had some 15nf caps laying around that I stacked parallel) – the Buff’n’blend seems to work correctly again. The only thing that’s bothering me is that there is now a high pitched noise when using a switch mode power supply (I think I didn’t notice any noise when I assembled and checked the buff’n’blen outside of the enclosure with that power supply, but maybe my memory plays tricks on me and I just didn’t pay enough attention at that time) – however the noise is gone when using a high quality power supply so eliminating that noise is only a nice to have. As soon as I receive the replasement parts and the multimeter I’ll check everything again.

So far I’m really happy with the buff’n’blend, so thank you very much for your support!

[Barry]

A good tip is to have a battery on hand that has a 2.1mm tip so you can do a quick noise check. Batteries do not produce noise so if a battery is quiet and another power source does make noise then get rid of it. You do not want any cheap noisy power supplies in your chain to pass noise on down the line.

[Author]

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