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Dear all, I’m having problems with the Mini-Me chorus. This is my first project, and I am not en elctronics expert, so be warned: I my need a bit more support than others… however I am eager to learn & will try as much info on the PCB as possible. I have soldered the PCB & found a trimmer position where the Mini-Me changes the sound, but it does not modulate but instead distorts the sound. I have a sound sample (playing some I-VI-IV-V with my bass) but cannot upload it into this threat. I know from this threat that there may be a problem with corrupt ICs but this user did not hear anything from the chorus. My Mini-Me “at least” does something with the sound.
Please find below measurements of the voltages of the ICs and transistors. Some readings are marked with an *, these fluctuated a lot (I have tried to read average vakues). I haven’t had time yet to take good photos but triple checked the correct placement of the components. Any help would be really appreciated.Daniel
Hi Daniel, so many questions without photos.
What version of board is this? or at least does it have the Jumper section?
If so what is the placement orientation of the Jumper pair?
Is G2 ground also hooked up?
Voltages for MN3007 are very wrong. Depending on the above questions this is likely the area of focus.
Hello Barry,
thanks for your quick reply! Below are some photos of the PCB.Board should be the current version. I ordered it in June at Musikdings.de
Jumpers are placed for the V3207D (IC and jumpers should be visible in the photos).
G2 is connected to GND-
I will measure the voltages of MN3007 a second time (no time today, unfortunately) & will post results if they are different.
Many thanks!! Daniel
Also, I have to admit (newbie mistake) that I have soldered the transistors directly into the board, becaus I didn’t know that it is good practice to use sockets. I am actually thinking of buying & building a second Mini-Me, but it is currentyl out of stock at Musikdings.
Best regards, Daniel
And in case you wonder: the C18 capacitor will be replaced by a Rotosound board. Hence the two yellow cables.
DanielWhat is at the end of the two yellow wires? In other words there needs to be a capacitor.
I would reflow the whole project as a normal part of troubleshooting. I can’t find anything wrong component or orientation wise.
Re-measure v3207 after doing all of that and report back.
Hello Barry, The two wires are currently connected to an 150pF capacitor, I will later connect them to a Rotosound PCB.
I definitely wil rem-measure the v3207.
Just one question: what does “reflow” mean? (Please excuse my asking, I am not a native English speaker).
Best regards, Daniel
Barry is offline right now. “reflow” means to remove all active components such as ICs and transistors and then reheat all solder joints to make the solder melt. It only requires a few seconds to reheat each one. This will fix any “cold” solder joints. Then replace the ICs and transistors and retest the circuit.
Remeasure the voltages on the MN3007. Those numbers were bad.
Dear all, I have reflowed to PCB & taken some more measurents. Also, I have built an audio probe and listened to the signal at different points of the PCB, following the signal flow. Please read the audio probe results as follows:
“clean” –> I hear the clean sound of my bass guitar without distortion and modulation
“distorted” –> the sound of the bass guitar is distorted. I can’t say for certain if it is also modulated tor to the high amount of distortion
“dead” –> I can’t her the sound of the bass guitar
Below are the results. Many thanks already now for your kind support.
Best regards, Daniel
I have used an passive Ibanez bass and an active Fender Jazz bass, which can be played in parallel mode. Both distort. When I turn done the volume odf the picks really low, then the distortion disappears. But also the signal is so low that it is not useable anymore.
Best regards, DanielYour voltages are way off for the V3207 chip. Not sure what is going on here.
Remove the chip and test voltages in the empty socket then report back.
Hello Barry, thanks a lot!
I have removed IC2, all other ICs still in place, no instrument or amplifier connected. Here are the voltage reading. Voltage supplied was 9.1V.
I hope that helps, Daniel
Dear Barry, based on my voltage readings of IC2, can you give me a hint how to fix the Mini-ME?
Many thanks in advance, DanielApologies as I have been losing sleep trying to get 30 new build docs done in the next two weeks for all updated boards. With that said any assistance I can get in the forum is appreciated at this time especially.
So Voltages are correct or close enough for all 8 pins un-socketed. I am wondering if your chip is bad because when you do install the chip your voltages turn very bad. Also check for bridges somewhere. I would use light and a scraper to go between any questionable areas. The same can be said for a bad solder joint although I know I asked you to re-flow.
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