Small Clone Debug help please!

[Al Heeley]

certainly worth a quick'n'easy check Craig, i have a duplicate set to try as well.

[Al Heeley]

no joy down that route. Getting a bit stuck now. Can anyone help explain to me the signal path to the delay chip as I can't get much signal the other side of the diode?

[solderman]

How about checking if the diode is turned correctly or if it is OK. Does the stripe on the diode point towards the emitter of Q1? check the diode with your DMM
Or do you have a solderbridge some where around the diode??

You should have a clear signal at pin 3 and a some what distorted signal on 7-8 of the 3007 eaven without the LFO working.

[Al Heeley]

rechecked and replaced but no joy. I'm getting 7.8v on the striped side feeding from Q1 emitter, and 8.2v from the anode which leads to the 33k and 12k resistors and on to pin 3 of the mn3007.
Is this too much? Is it swaping the input signal?

I rechecked MN3007 voltages:
1= 8.1
2= 4.1
3= 8.1
4= 0
5= 0
6= 4.0
7= 6.1
8= 6.1

Q2:
e=5.4
b=6
c=8.8

Does all that look ok?

[Al Heeley]

Come on guys - one last push this weekend to try and get it working before I bin it and sulk. Free packet of assorted resistors to anyone who can get this sorted!!

[rustypinto]

I think you're getting close, don't give up! Sounds like you're confident that nothing is getting through the BBD. It could be a bad bias, bad chip, or no clock.

Your second post says pin 3 of the MN3007 = 5.5V, but when you re-checked the MN3007 you get 8.1V. Is that still true? If so, thats a problem. BBDs generally bias anywhere between +/- ~1V of Vcc/2. My version measures 5V. Make sure the 12k/33k/39k resistors are populated correctly and maybe look for shorts or cold solder joints surrounding those resistors and the MN3007.

[Al Heeley]

OK, I've rechecked the 39k, 33k and 12k resistors, values & joints ok. Rechecked MN3007 pin 3 using a different battery, getting an oscillating voltage from 7.53 to 7.74v. I guess this means the clock signal is reaching the delay chip. Could it be a duff chip?

[astrovic]

Hey Al, don't give up now!

It seems that your signal stops at D1 and isn't getting to the MN3007.  You need to hear clean signal at pin 3 of the MN3007, and chorused signal at pin 7 of that chip.  Have you thought about looking at D1?  Is it oriented the correct way?  Maybe try replacing it?

I'm currently in the middle of debugging mine - this unit is death by a thousand cuts.  I eventually goit it working, then trashed the 1M Rlog pot putting it in the case (don't ask), and just got a replacement.  Wired in the pot, and its not working again!

My problem is I'm a chorused signal out of the MN3007, but that signal stops at the 20K resistor just after Pad D.  What gives?  i really don't get it, but I am determined to beat this little bastard...

EDIT: got it - stupid cold solder grumble grumble.

All good.

Let's get yours going now, Al! 

[Al Heeley]

Disheartened by hours of debugging I gave the pedal to a good friend who is a proper electronics whizz. He looked at it over the weekend and came back with 3 separate problems:
1) Tonepad schematic had one of the transistors the wrong way round (don't know which one!)
2) I replaced the trimpot with a differnt type and one of the legs had a bad solder.
3) Wrong value cap inserted by me, order of 100 too big. Oops!
Quite excited now, I had written this off, but now will go retrieve it adn box up tonite, and try out the 4 cap value rotary switch addition.
Still no 1 meg reverse log pot available - hope it will work ok with normal taper.

[solderman]

Hi
Glad you got it going. Its a really nice effect.
About 1. I don't think Tonpad has it wrong all though you might have used transistor with a different pinout than the one in the BOM.  Ask your friend witch one it was?

[Al Heeley]

I think you're right - it was the 5087 transistor.
Really sweet chorus and a wide range of tones.
Heres a pic:


Here's a small sound / demo clip:  http://www.youtube.com/watch?v=odOiXYqUBaU