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Thanks so much for the photos. That’s very helpful.
I notice that you do have a lot of rough looking solder joints. Most likely, the messiness of your board is causing these problems you are experiencing. You might want to try to clean up the joints with lots of solder on them…they will have a tendency to become oxidized and crack. There also seem to be a lot of tiny pieces of solder sticking out from many of the pads…these can short to the ground plane or other pads very easily…please clean those up by removing much of the extra solder on most of the pads. The microcontroller has a lot of burnt flux around many of the pins that you have been soldering to a lot (especially around pin 6)…try to remove this with some high percentage rubbing alcohol or acetone on a q-tip. It actually can become somewhat conductive. In general, try to use less solder on each joint…it’s much easier to control if you use solder that is very thin in diameter (I use .8mm wide solder). Also, it’s usually much better to use much thinner wire to run jumpers so it’s easier to control and you don’t accidentally short pins together with the thicker wire.
There is a large blob of solder on one of the pins of R11 that I am concerned may be shorting to ground…try to fix that.
There is a via right below the “R” of the word “RED” next to the bypass led. Make sure that nothing is shorted to that via from the midi in header.
For questions 2, I was asking about what is happening on pin 6 of the microcontroller when you press the bypass switch (not the LED). Make sure the bypass LED pins aren’t shorted before you check this (just in case they are connected).
The goal is to get the microcontroller cleaned up enough so that we get 5v on pin 6. If you are confident in your jumper running ability, it may help to cut the trace coming from pin 6 to ensure that nothing around the LED is causing this 4V issue.
-BrachHi German,
Just to be clear, you’re saying that when the red LED by the bypass switch is on the tremolo effect is bypassed, and when the red LED is off the tremolo circuit is engaged and you hear the tremolo. Is this correct?
-BrachPins 13 and 14 usually measure only about .5 ohms to ground because they are across the relay’s coils, so it may seem that they are shorted to ground but they are not actually. I’m pretty sure that is what you are discovering here.
Because pin 6 is programmed to low when the LED is not on, it should measure a very low resistance to ground. As with the other pins, it may seem like it’s shorted to ground but it’s probably not.First answer this: Are you sure that neither side of the LED is making connection to the parts of the circuit it is supposed to connect to? Is either pin of the LED connected to R11 or pin 6 of the IC? You mentioned this in your first post, but it seems unlikely that both pins aren’t connected to anything unless your board has been damaged somehow.
I’m curious about the socket…sometimes they don’t make good connection to the IC pins. (1) What is the resistance between the the solder joint of pin 6 on the socket and pin 6 of the IC? (2) Also, does the 4V on the IC pin change when you press the bypass switch? (3) Does the voltage on the pin change with the LED out of the circuit? I’m wondering if the LED has been damaged and is only dropping 1 volt, instead of the 2 volts it needs to light up.
Please answer these 3 questions directly.
As far as your pedal not working anymore, it sounds like there may be some opens or shorts on your board somewhere. It would be helpful to me if I could see your board. If you could send me some detailed, in focus photos of both sides of your board, that would give me a better understanding of what might be wrong.
-BrachI’m confused…Are you getting 4v (or any voltage drop) across the red LED?
Are you getting continuity from the solder joint of pin 6 on the microcontroller socket to the LED?
Did you re-seat the microcontroller in it’s socket?
Did you test the polarity of the LED, as it’s installed?
While you are answering these questions please also check (and even re-flow) the solder joints on the microcontroller…specifically looking for tiny bridges around pin 6.
-BrachThe good news is everything else is working fine, so this LED should be too hard to fix…in theory.
First of all, R11 should be hooked up to the LED cathode (the round pad), not anode (the square pad); and the LED anode, not cathode, should be hooked up the the U1 pin 6….please note the schematic. Reverse your hookup wires and see if that fixes the problem.
If not, re-seat the microcontroller in it’s socket to make sure there’s not something wrong with one of the pin connections.
There is a chance that the LED could be in backwards. Using your diode tester on your multimeter, with the red lead on the square pad and the black lead on the round pad you should get around 1.7V across the red LED (and around 1.8V on the green LED).
You can just run a jumper from pin 1 of the microcontroller to it’s pad. Pin 1 is the reset pin so it shouldn’t matter for this LED problem…but you do need to hook it up to keep your pedal from resetting every time pin 1 drifts low.
Let me know what you find with the LED.
-BrachThis type of problem is usually caused by a bad connection somewhere in the analog audio side of of the circuit. Start by checking the solder joints on J1. I suggest that you re-flow all of them to make sure they are all good. If that doesn’t work then check (and even re-flow) all you solder joints on the following components:
R14, R15, R16, C8, C10, R19, U3, C9, C3, C4, VR9, R22, C13, C11
Also, make sure there are no solder bridges across any leads.
Good luck.
-BrachAhh! That was it! I’m really glad to hear that fixed it…of course there was nothing else that it could have been at this point because we checked and re-checked everything else. My guess is that it must have been damaged through static electricity.
Enjoy your Quaverato. I hope it gives you years of great tone!
-BrachGood! I’m glad it’s up and working now.
Yes, you will need to re-calibrate the high and low trim pots. The given values for those were just starting points. Now you need to tweak them to the tone you like.
Good luck.
-BrachThat’s great!
In reviewing the previous picture I sent you, I realized I got the jumpers backwards…TP4 should go to R5 and TP2 should go to R4. Sorry! That may be causing your harmonic mix knob problem.
If that doesn’t fix the harmonic mix knob issue then it’s probably because JP3 is damaged and signal isn’t getting through. You can run a small jumper across the blue pads in the previous picture (maybe try this on the solder side of the board if the top side is too cluttered with components). That will bypass JP3.
Good luck!
-BrachThis probably means that the solder jumpers on both the high and low sides are not making connection. Use some small gauge wire and run some jumpers as in the picture…
This bypasses JP2 and JP4. But you also need to make sure that JP3 and JP1 are soldered correctly. You can see if JP1 and JP3 are connected properly if both the green pads are connected and both the blue pads are connected…use your continuity tester.
If they are not connected, to fix them you can get a tiny bare wire (like a short component lead) and solder that to the 2 pads of the solder jumper…if that helps to get the connection made.
-BrachDo you get any sound when you touch pin 1 of the relay with your metal tweezers? What about R4 and R5?
I wouldn’t start replacing components yet. You might want to wait until you re-flash it. I’m pretty sure your LM386 was good because it made noise when you shorted some pins together. The 6N138 definitely won’t be causing the problem.
I just talked to Glen and he thought he sent Koma a usbtiny for this very purpose…but maybe he was mistaken. We’ll send them one…so you can use it there. You can order your own, but you probably don’t need to. We’ll try to get it in the mail tomorrow.
Unfortunately, at this time our ZDL Updater software is for PC only. Sorry.
-BrachOk, thanks for the clarification.
Please don’t bridge C1 with the volume pot…it’s not helpful because as you can see from the schematic they are on opposite sides of the circuit.
If the effect circuit is bypassed (the red led by the bypass footswitch is off) the volume pot should not be controlling the signal at all. The volume pot should only be controlling the signal when the red led is on. Is this happening with your pedal?
Is nothing happening when you touch TP3 or 1, even when the effect is engaged and the depth knob is fully counter-clockwise?…you shouldn’t hear anything when the effect is bypassed. What about when you touch TP 4 and 2?…theoretically, you should hear something with TP4 and 2. Try touching the test points with something metal…I used a pair of tweezers to touch the test points on the Quaverato on my desk and it made noise on each of them (TP1-4)…but only when the effect was engaged.
VR10 is after the LDR’s so you should hear something from that when the effect is engaged.
-Brach
