Author Topic: Building the tap tempo tremolo  (Read 241317 times)

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ElectricDruid

Re: Building the tap tempo tremolo
« Reply #980 on: January 23, 2017, 08:29:13 AM »
Sounds like there's something seriously wrong around the 2N3904. That shouldn't be getting hot.

If that's true, and there's a mistake there somewhere, that'll explain why there's no audio. Without that transistor turning the optocoupler on, you'll be stuck at permanently off.

HTH,
Tom

Re: Building the tap tempo tremolo
« Reply #981 on: January 23, 2017, 11:49:55 AM »
It's just strange that every feature is working properly outside of the audio. I'll check to see if I have an incorrect resistor or cap values somewhere perhaps. If that doesn't work, I'll order in a new NSL-32. If THAT doesn't seem to alleviate the issue, I'll just resort to seppuku.

Taylor

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Re: Building the tap tempo tremolo
« Reply #982 on: January 23, 2017, 04:47:38 PM »
Since you're saying all the knobs work but the audio path doesn't, the LED must be flashing, but you also said that the LED indicator doesn't activate. I'm sure that I just misunderstood part of that, but could you clarify what the LED is doing?

If you hear ticking but no guitar, that tells us that everything in the audio path after the optocoupler to the output is probably working. It could be a short/open somewhere between the input pad on the PCB and the opto.

But as Tom says, the 3904 heating up, and what you said about the trims seems to point to an issue with that transistor. You've probably already checked over all this, but make sure it's the right part number (and not, say, a 2n3906) and it's in the right way. Can you post voltages for all the pins of the transistor and ICs (including 78L05 regulator)?

Re: Building the tap tempo tremolo
« Reply #983 on: January 24, 2017, 10:26:32 AM »
I found the issue was a destroyed pad where the 100uf electrolytic was alongside the transistor. I was able to get it to work for just a brief moment and endowed the trimpots with the ability to adjust the LFO indicator, but it died shortly afterward and then the 10 Ohm resistor burnt to a crisp. I started this build when I was relatively new to being a DIY pedal enthusiast, so I'm going to purchase another PCB and try this again. With the new 3PDT boards I purchase for another build, everything should be pretty simple to adjust now that I have a bit more experience.

Thanks again guys.

Let me know if you happen to have some more boards shipped in so that I may order from the site.
« Last Edit: January 24, 2017, 12:23:46 PM by Andrew B. Campbell »

Taylor

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Re: Building the tap tempo tremolo
« Reply #984 on: January 24, 2017, 03:49:45 PM »
The board might still be salvageable - if you post a photo I could give a suggestion on an alternate way to connect the parts with lifted pads. Sometimes it's easy to swing a component leg over to a via that the pad was connected to. But, the tap tempo trem boards are in stock if you wanted to start with a fresh one.

dafortier

Re: Building the tap tempo tremolo
« Reply #985 on: July 30, 2017, 10:42:54 AM »
Here's one I haven't seen yet. Just built this one and like everyone else, I have some ticking. Been able to trim it out mostly. And it's only on the first three wave forms, however, it's there even when the effect is off. Most pronounced when it's off actually.

I'm not sure why it's passing through even when it's bypassed. My 3PDT switch is wired per the drawing build doc.

I suspect a grounding issue but not sure where it could be.  The board ground is wired to the neg on the power jack and then to the sleeve of the input jack.

Any ideas?

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Taylor

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Re: Building the tap tempo tremolo
« Reply #986 on: July 30, 2017, 03:01:33 PM »
Here's the alternate version of the bypass wiring, which grounds the LFO signal while bypassed, should solve the ticking in bypass:

http://imgur.com/fi592fn

dafortier

Re: Building the tap tempo tremolo
« Reply #987 on: July 30, 2017, 09:28:30 PM »
Here's the alternate version of the bypass wiring, which grounds the LFO signal while bypassed, should solve the ticking in bypass:

http://imgur.com/fi592fn
Yep. That worked like a champ. Thanks!!

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dafortier

Re: Building the tap tempo tremolo
« Reply #988 on: August 12, 2017, 09:53:23 AM »
One more thing. I many have fried something.

I re-boxed it and while doing so, I made a couple of changes.

I socketed c15 so I could try different values. I inserted a 1uf to try first.

Also removed the wave distort knob and soldered in the resistors in its place.

I wired the led directly to the PCB, bypassing the switch so it's always on.

Lastly I added a status led.

When I first powered it on it worked for about 15 seconds then it just shut off. Took it back to my work bench and plugged it in and the resistor right next to the rectifier diode got red hot and burned out!

I replaced c15 with it's proper value and replaced the diode and resistor. Same thing happened. :(

Someone know what's causing that resistor to overheat? Where should I start looking? I already checked for shorts or solder bridges.

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dafortier

Re: Building the tap tempo tremolo
« Reply #989 on: August 12, 2017, 01:34:37 PM »
One more thing. I many have fried something.

I re-boxed it and while doing so, I made a couple of changes.

I socketed c15 so I could try different values. I inserted a 1uf to try first.

Also removed the wave distort knob and soldered in the resistors in its place.

I wired the led directly to the PCB, bypassing the switch so it's always on.

Lastly I added a status led.

When I first powered it on it worked for about 15 seconds then it just shut off. Took it back to my work bench and plugged it in and the resistor right next to the rectifier diode got red hot and burned out!

I replaced c15 with it's proper value and replaced the diode and resistor. Same thing happened. :(

Someone know what's causing that resistor to overheat? Where should I start looking? I already checked for shorts or solder bridges.

Sent from my VS995 using Tapatalk
Nvmd.. I'm a dummy. Don't hook up a 12v power supply to a 9v circuit.

Can delete this and the previous post.

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Taylor

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Re: Building the tap tempo tremolo
« Reply #990 on: August 12, 2017, 01:35:32 PM »
Edit: ah, glad it worked out.  :)

Original post:
If your status LED is taking power from the board, maybe try wiring it straight to the power jack instead. You could also try replacing the resistor that burnt out with one double the value - it has to do with filtering the power so changing this value won't affect the audio or LFO function.

ferdinandstrat

Re: Building the tap tempo tremolo
« Reply #991 on: August 13, 2017, 01:08:17 PM »
Hey guys, did anyone encounter a problem where occasionally the pedal will lose volume when bypassed?

Taylor

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Re: Building the tap tempo tremolo
« Reply #992 on: August 13, 2017, 02:34:01 PM »
If you've wired it up as true bypass using a regular 3PDT switch, then you might have an intermittent wire/cold solder joint on your bypass switch or somewhere in the ground wiring off-board.