Hey all! I have been working on the Tonepad Boss CE-2 Clone and am having issues. The dry signal is going through sounding great, but I am not getting any chorus tone coming through. I took an audio probe to the circuit, and signal is going into pin 3 of the MN3007 just fine, but I am getting 0 output from pin 8 of the MN3007. So something is going wrong with the modulation section, but I'm not really sure how to troubleshoot these IC's.
The voltages are as follows:
MN3007:
1 - 7.82
2 - 4.15
3 - 3.27
4 - 1.31
5 - 0
6 - 3.50
7 - 1.25
8 - 1.27
MN3101:
1 - 7.68
2 - 3.45
3 - 0
4 - 4.13
5 - 0.2
6 - 6.81
7 - 2.51
8 - 1.42
Does anybody know what sort of voltages I should be getting on the MN3007 and the MN3101? Or any ideas on how to figure out what's wrong? Also, as I'm measuring the voltages, MN3007 is feeling pretty toasty. I don't imagine that's supposed to get that warm. Any thoughts would be greatly appreciated.
Thanks y'all!
From your voltages I can see that you do have a problem. You state the the MN3007 is getting toasty - this is not good. R52 should also be getting warm too. This should not happen.
Remove the MN3007 and measure the voltage on pin 1 of the MN3101. It will probably now read above 8.5V if it is a genuine MN3101 and R52 will run at a cooler temperature. If the voltage does come up then you either have a faulty MN3007 or a non-genuine unit.
Where did you source the MN3007 from?
I took a gamble and ordered both IC's from eBay. I've had good luck ordering from there until now, but I may have pressed my luck too far this time.
Removing MN3007, the voltages on MN31010 are now as follows:
1 - 9.39
2 - 4.76
3 - 0
4 - 4.79
5 - 0.2
6 - 8.47
7 - 2.96
8 - 0.63
This is my first attempt at a BBD build. So do these voltages suggest that my MN3101 is working properly, and I got a bad MN3007? Is there anything else I should/could try before shelling out more money for parts? Thanks for the help.
In order to work properly, MN3007 needs:
a proper clock on pins 2 and 6,
a proper bias voltage at pin 3,
and a proper load on output pins (pull up).
Check if you have them all
The voltages on the MN3101 look correct. The fact that the voltage on pin 1 came up when you removed the MN3007 chip certainly means that the MN3007 is no good. You can test the MN3101 further if you have an oscilloscope but I think that you will find that it is OK.
Sourcing 'hard to find' chips on eBay can be a bitter experience but sometimes you succeed. I do recommend buying from known reliable suppliers such as Smallbear. I think that he still has stocks of the MN3007.
Took my O-scope to pins 2 and 6 of the MN3101, and it looks like it's giving a decent clock signal. So I'm going to conclude for now that this chip works fine. I checked the socket connections on the MN3007 and it appears to be connected to everything properly.
So I guess I'll have to assume that I got a dud, and I need to hit up SmallBear for a real one. Unless there are other suggestions to check that I'm missing something else obvious.
In case anybody who stumbles on this thread in the future is curious, I got a new MN3007 from Smallbear today. Popped it in the socket, and the pedal worked right away. Lesson learned kids: don't buy BBD's from eBay. The chips aren't cheap, but if you find a deal on one, it's probably too good to be true.