Zombie Chorus Help

[ranchak]

I just finished John Hollis' Zombie chorus with the changes by R.G. Seems like my luck isn't too good these days. I think I've built three projects and I'm 0-3. Enough of self pity, I built this on PCB. I used:

U1 = TL062.
U2 = MN3007
U3 = TL062
U4 = MN3007

I have checked my solder joints, cap polarity. U2 gets extremely hot, hot enough to burn your finger. I took voltage readings on all of the chips. The voltage readings for U2 are with the chip removed.

V=13.16

U1

1=7.94
2=7.92
3=7.2
4=0
5=12.93
6=12.49
7=12.50
8=13.17


U2
1=13.17
2=6.53
3=7.95
4=0
5=0
6=6.64
7=13.13
8=13.13


U3

1=7.9-8.09
2=7.94
3=8.29-8.41
4=0
5=7.94
6=8.18
7=8.49-8.59
8=13.18

U4

1=0
2=6.54
3=6.65
4=6.65
5=0
6=1.456
7=4.154
8=0
9=8.42-8.52
10=7.43-7.51
11=7.15-7.24
12=11.09
13=0
14=13.20
15=.03
16=13.20


No substitution for resistor or cap values. With an Audio Probe I have signal at Pins 1,2,3 of U1 and nothing past this point. Thanks in advance for the help.

[oldrocker]

One of the IC chips should be a CD4046 Phase Lock Loop.  I assume it's a typo.  Double check that and get back and see if we can't get you going.  Question.  Why is the input supply voltage so high?  Hopefully all the caps you used are rated to handle that high of a voltage.

[ranchak]

Old Rocker, you are right. U4 is a CD4046 (I was tired when I posted this last night). I am using a 12v wallwart, and all of my caps are rated at least 16v. I can try going to 9v, I think I have a fresh battery.

[oldrocker]

OK yeah I get tired and mis-type all the time.  Just look at some of my past threads.   Well I'm not sure about the supply voltage although the John Hollis schem does show 9 volts but I don't know if it's crucial.  To compare voltages for IC's most builders are probably using 9 volts so it would be harder to tell if the voltages you're getting are correct. 
Since you're having some build problems you're a brave guy taking on a Zombie.  Although if you can get this working you won't be disappointed.  I perfboarded this a while back and this is one of my favorite pedals.  I added the ring modulation switch mod and the wet dry mix mod too.

[ranchak]

Actually I was doing well with my builds, everything was working. Then I built a double Peppermill and things started going south. A single Peppermill worked fine, and all I wanted was two Peppermills in one box, like an A/B. I've built them twice and still can't find my mistake. I've wired them separately and still no luck. I didn't think the Zombie would be that difficult, but I can see that I am mistaken. I'll try to get some readings from a 9v power supply and get them posted.

[oldrocker]

Question.  Did you PCB it or perfboard the project?

[ranchak]

I used a PCB, I installed a 9v regulator and the MN3007 doesn't get anywhere near as hot. I thought I bought two of these and I was going to try another one (thought maybe I fried this one). I guess at $10 a pop I only ordered one. I really don't think this is the problem, but I really don't know. On a good note I built the Guvnor and it worked first try! I need to change the tone values for the mids and highs. I want to get more of a scooped sound, something like a VOX.

[oldrocker]

I've been wanting to build a Guvnor and never got around to it.  I wasn't sure if I'd like it or not.  I may breadboard one up and give it a try.

[ranchak]

O.K. here are new voltage figures:

U1 = TL062
U2 = MN3007
U3 = TL062
U4 = CD4046


V=11.05

U1

1=.545
2=2.356-2.416
3=5.62-5.88
4=0
5=1.404
6=1.389
7=1.390
8=10.95


U2
1=10.95
2=10.45
3=.511
4=0
5=0
6=5.97
7=1.423
8=1.423


U3

1=10.28
2=6.18-6.44
3=4.18-8.93
4=-.001
5=6.18-6.43
6=4.63
7=4.97-8.18
8=10.92

U4

1=0.146
2=10.40
3=6.04-6.58
4=6.03
5=0
6=1.262
7=1.264
8=0
9=6.17-6.40
10=5.39-5.78
11=4.92-5.19
12=8.88
13=.145
14=10.93
15=.124
16=10.93


I notice that there are some significant changes in my voltage readings from my first posting. Hopefully I have enough info here to get some feedback and determine my next step.

[nordine]

what i think is weird is that even using a 9V regulator you get 11V... is that set up correctly?

if i remember good the zombie has some mmm special 'bias tricks'... so for it to work you must provide the conditions, and the first condition meet sould be an appropiate input voltage

now.. does it makes any sound? ....have you listened to it? ...because sweepings or whooshings will tell you a lot about whats working and what could be failing

good luck!

[oldrocker]

There are bias voltage mods that I added to mine.  For the clock section I added the voltage divider using two 10K resistors.  This separate from the original bias voltage setup.  I still get some faint clicking and I may look deeper into that on mine.
I agree with the above statement.  A regulated 9 volts should give you...well 9 volts or there abouts.  I don't know if that would be the problem why it's not working.  I will try and get the voltages for you.  Although they will be measured using a 9 volt battery.

[ranchak]

If you see I have 11.05v as input voltage, this probably explains the 10v input voltages. I am going to build a regulated power supply (or buy a new 9 volt) to help and try to get this worked out. I do hear a "swooshing" sound when I turn one of the pots, but no signal from the guitar. I'l post some new readings once I get them.

[nordine]

be careful with over-voltage the mn3007

i had a zombie working with a mn3207 (mn3007 equivalent) on a breadboard... accidentally fed it with 12V regulated.. and boom, the chip was gone ...i don't know if those chips tolerate greater voltages than 9V on theory, but mine died with 12V, so try any fresh chip with a sure 9V source