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Main thing we need to figure out is if the microcontroller is receiving 5V from the power supply.
The red points on the voltage chart are showing all the points that should measure 5V from ground. Theoretically all the red points should be connected together and showing continuity to each other because they are all on the same voltage rail, but that’s not what we are testing.
Please test the red point on the microcontroller to see if it is getting 5V. If it is, then check to make sure R12 is soldered properly and is the correct value of resistance. If not, check the other red points to see if anything is receiving 5V.
Let me know.
-BrachFor flux remover…I make my own my mixing rubbing alcohol and acetone in a 1:1 ratio. It works pretty well. You can use a toothbrush or Q-tip to clean the flux off the board with it.
For most of the steps in the troubleshooting guide the pedal just needs to be powered on. Some steps will direct you to press the bypass switch.
I don’t know what you are asking with your last question. Just attach the wires to the proper places…which it looks like you’ve already done, except for the wire that fell off.The main thing I still need to know is what step you get stuck on in the troubleshooting manual.
What step in the troubleshooting guide did you get stopped?
I couldn’t see in the photo, but make sure you have a jumper from TP4 to R5.
-BrachThat is good that it’s working now…at least somewhat.
The note staying on thing can happen when the keyboard doesn’t have a good ground reference. So make sure the power supply you are using is solid. It can also happen if one of the keyboard resistors isn’t soldered properly or has too much solder on its joints.
-BrachI’m glad it’s working, but it is very concerning that the voltage at TP6 is nearly twice what it should be. My first thought is to ask if you are sure you are measuring it correctly. If so, is R3 and R4 the correct values? What voltage do you get at TP10?
-BrachI was wondering if that trouble was somehow related to the meter. I’m glad to hear you figured it out.
Keep me posted when you install the new parts.
Good luck.
-BrachYes, that would do it! I didn’t even notice that…I was so focused on looking at the solder joints! Good noticing. Chances are, the opamp has broken now, so you do need to replace it. Please follow the steps in this blog to remove it, as to keep your board from getting damaged: https://zeppelindesignlabs.com/the-easy-way-to-remove-dip-ics/
You can order a new IC and socket from https://www.taydaelectronics.com/
Tayda is a good place to get all kinds of pedal parts at a reasonable price.
On a side note, I’m glad that you got the trim pot set.
-BrachAre you able to get any reading when you measure across the trim pot’s solder joints, not test points?
If not, are you able to get any reading when you touch the 2 meter probes together?…you should be getting 0 resistance.
You probably don’t have to remove all the pots, if you can just suck off most of the solder, that should be sufficient.
-BrachThanks for the photos you emailed us. Unfortunately, due to the resolution and the focus of the photos I wasn’t able to see too many close details of the board. From what I was able to see, a good number of the solder joints still need to be flowed better. Good solder joints don’t have any sharp edges because those are the places (due to capillary action) that the flux won’t cover. You need flux to cover all the joint because it acts as a sealant against oxygen and moisture. If oxygen can penetrate the solder joint, then it will become “cold” and eventually crack. So that’s why good solder joints are important to have. After you re-flow the joints go over the board really well (with a magnifying glass) to look for tiny flecks or balls of solder that could be shorting together some pins. Sorry, I know this work is tedious, but it has to be done if you want a good working pedal.
With the LED fading out…another thing to make sure is that the paper underneath the pots don’t have any punctures in them otherwise it could cause a short, which could cause this problem.
Were you able to have any better luck with your meter? Were you able to measure the resistance between the test points?
-BrachI think that original solder from Harbor Freight might have been for plumbers to sweat pipes with. That stuff either has no flux in it or what they call “acid core flux” which is really corrosive to circuit boards. Hopefully it didn’t have any flux in it. The solder that is designed for electronics has rosin core flux in it. There is a “proper” ratio of flux to solder to get the solder to flow really well, so if your original solder didn’t have flux in it, it may be better to suck off the solder from most of the joints and re-flow them all with the good solder. You may have better luck getting this thing to work that way, and it will stay working longer with better solder joints…they will be less likely to get oxidized and crack.
-BrachThanks for giving the Quaverato a go. If nothing else, I’m sure you’ll learn a lot about assembling pedals.
Do you know what kind of solder you were using and what kind you switched to (you could send pictures of that too)? It sounds like your original hard-to-melt solder might have been lead-free solder. That stuff is really hard to work with and I don’t suggest using it unless you have a lot of experience soldering. The way you were describing the solder that ended up using sounds like lead/tin solder. It’s much easier to use, but it doesn’t mix too well with lead-free solder. It’s hard to get good solder joints when both types of alloys are used. The type of solder you use is actually pretty important in helping you have a successful build.
If the solder was taking longer than 2 seconds to melt then your soldering iron wasn’t hot enough. Different solder alloys melt at different temperatures.
You might have damaged your TL074, but probably not. They are more robust than the manual makes it sound. The fact that you were conscientious of that makes me think it’s probably fine.
Google drive (or some other file/photo sharing site) is probably the best way to share the photos.
Let me know about the photos.
-Brach808ROSS,
If you were able to successfully re-flash it then the ISP header must be working properly, so no need to continue testing it.
For lead free solder you should have your iron set to at least 350 degrees C. Depending on the type, you may need to set it more in the range of 370. Keep in mind, the extra hot temperatures are more prone to damage the board or the components so use your flux so the solder flows quickly.
Good luck!
-BrachMichael,
It seems like your board has some serious issues. My guess is that they are related to solder joints…possibly some bridged joints somewhere. So don’t power it on until we can get it checked out.
It would be helpful for me to see some detailed, in focus pictures of both sides of your board. Showing as many solder joints as possible (lift the pots up to show the joints under them). I might be able to see something that is causing the problem.
As far as getting “OL” on your meter… Most meters use “OL” (which stands for overload) if it can’t get a proper reading or the reading is too high for it to display. Make sure the battery in your meter is good and it’s working correctly (and the leads aren’t broken). Make sure the meter is set to read resistance. If it still is giving an “OL” when you measure TP5 and 6 it means that it is measuring infinity, which is an open circuit, so make sure the gain trim pot is soldered properly.
-Brach808ROSS,
Thank you for the photos…they are worth at least 1000 words.
From what I can tell from the photos most of the joints seem like they could use some re-flowing. It looks like you might need to turn up the heat on your soldering iron. What kind of solder are you using? Lead/tin solder is the best and easiest to use. Lead-free solder is much more difficult to get to flow correctly and requires much more heat.
If a joint has too much solder on it, then use a solder sucker and remove most of the solder and then re-flow it.
The solder that you should be using has a “rosin core” in it, which is what we call flux. It’s the stuff that allows the solder to flow smoothly and easily. So, when you re-flow the solder joints you aren’t trying to add more solder to the joint as much as you are really just adding more flux to the joint to get it to flow better. You can get containers of just flux; often they come in a pen or marker form so you can “draw” more flux on the joint before you heat it up…but you don’t need that in this case.
I can’t quite see the details of the ISP pins. I can’t see how you might have damaged the PCB there. You can use your continuity tester on your multimeter to check to see if any adjacent pins are connected (they shouldn’t be). Also please check to make sure they aren’t shorted to the ground plane. There is only one ISP pin that should be connected to ground.
When you flashed the software, did the computer say it was able to connect to the microcontroller and was the flash successful?
The fact that you are able to hear something when you short the volume pot pins means the analog section is probably working fine. The problem is probably with the digital circuit.
Keep me posted.
-BrachTom,
There is several things going on here. One thing is that you weren’t in calibration mode, you were in the mode that tells you what software version you have…hence the flashing green light. The tap light will pulse normally in calibration mode, depending on where the depth knob is set.
When testing the pedal, please make sure you are using a guitar level signal. It sounds like you might be using a very hot signal which could give you different results than what I’m expecting. For an actual number use .1Vrms (100mVrms).
Are the sticky knobs physically sticking or are they just not responding when they are being turned? If it’s a physical resistance at certain points then you should make the knob setting jig from the manual and re-set them. You can remove the knobs for now, if it bothers you…use a fine tip sharpie marker and draw a line on the pot shaft where the knob pointer should be so you have an idea of where in the rotation it is.
Since you didn’t build this pedal, please make sure all the solder joints are good…don’t trust other people’s work. On principle, I would just re-flow them all. In my experience most, in not all, of these problems could easily be caused by bad solder joints, particularly the weird volume issue.
Try calibration mode again and let me know what you find.
-Brach
