Magnus modulus debug, help needed

Started by svstee, October 23, 2009, 06:44:33 PM

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svstee

I built a Magnus Modulus from the PCB layout (PCB made by John Lyons) found here
http://www.diystompboxes.com/smfforum/index.php?topic=72527.0
a few months ago and shelved it when it didn't work. I want to get this guy up and running. There is no modulation or delay at all, the LFO is not working, but the Gain control affects volume. I did not wire up the LED's, could that be a problem?
Voltages are as follows:

V+ 9.2

IC1, PT2339
1 3.9
2 2.4
3 0.9
4 0.9
5 3.9
6 2.4
7 3.7
8 3.7
9 5.9
10 3.9
11 0.0
12 0.0
13 0.4
14 3.9
15 3.9
16 0.6

IC2, NE5532:
1 4.0
2 3.8
3 3.8
4 0.0
5 4.0
6 4.0
7 4.0
8 9.2

IC3, NE5532:
1 1.3
2 0.9
3 0.5
4 0.0
5 0.5
6 1.3
7 1.3
8 9.2

J201
D 0.6
S 0.0
G 0.0

LM7805
1 5.0
2 0.0
3 9.2

Both lugs on each spst switches read the same,
Tails 3.7
Modulation 1.3
Tremolo 1.3

What does this look like to you? Thanks!

svstee


frequencycentral

I'll open mine up tomorrow and take some voltages.
http://www.frequencycentral.co.uk/

Questo è il fiore del partigiano morto per la libertà!

svstee

Thank you very much! Obviously, my LFO section isn't working right, but I have no idea why.

svstee

Anyone? I've looked around for voltages and found these:
http://www.diystompboxes.com/smfforum/index.php?topic=77940.0
but those were taken from the pedal in a non functioning state...

What can I do to get this build up and running?

dr.benway


svstee

I just dug this out of my junk pile, I really want to get it up and running.

J201 looks consistant with what others have posted.

I think I have the LED wiring wrong. Where do LED 1 and 2 at the bottom right corner of the PCB go?

svstee

Anyone? I know a bunch of people built from that PCB, where do LED 1 and 2 at the bottom right corner of the PCB go?

Thanks!

prnet

I think that ic3 5532 voltages are wrong..  ;) Thake a look at ic2. you should read something similar..

svstee

I Double checked all around there and don't see anything, but the LED 1 and 2 is still throwing me...

svstee

Bump on the "where do LED 1 and 2 at the bottom right corner of the PCB go" question.

svstee


Brymus

I havent built one so IDK ,but I am bumping the thread for you again...
Have you used the audio probe to trace the signal?
I'm no EE or even a tech,just a monkey with a soldering iron that can read,and follow instructions. ;D
My now defunct band http://www.facebook.com/TheZedLeppelinExperience

svstee

Have not gone through it with an audio probe, I figured I want to know where everything hooks up first rather than hunt and pick around.

dr.benway

Wondering if you got different voltage readings once the lfo/trem section worked. I've got practically the same readings on the jfet, the opamps but different on the PT2399 (more like in the 2.5 -4.4 range). I can post them once I get back home if needed.
Mine was working fine and then for some reason the trem/modulation just stopped. rechecked and redid my solder connections, looked for solder bridges but still no dice.

GP

hi... not necessarily a fix but pin 1 of the pt2399 should be at 5 volts... and i don't think pin 9 should be at 5.9