Troubleshooting 1st completed build

[Seven64]

Ok, so i just finshed my magnus modulus project and tried to fire it up.  the bypass doesnt work, and when i flip the bypass switch on i get a crazy tremolo/echo sound coming from the pedal.  it goes away if i turn the delay level all the way down, but if i just inch it up then the sound comes back and LOUD.  the gain knob also works, adding gain to the sound.  no other knobs or switches seem to do anything.

The only thing i did differently than the substitution is using the smallbear 3pdt wiring pcb's.

i dont even know where to start with troubleshooting, please help!!

[.Mike]

That's a pretty complex project for your first build. Most people start by building a series of boosters or fuzzes or distortions because they are usually simpler and easier to debug. Simple projects help new builders gain the tools and understanding needed to debug more complex projects, and the Magnus Modulus is definitely a complex project.

Start here: http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Good luck!

Mike

[Seven64]

i have been building circuit boards for a few years, and it never dawned on me that i could build effects pedals until a few months ago.  yes, it was a little complex, but i am very good at following directions and schematics.  i have also modded my bf-2 extensively and it sounds lightyears better.

i read the debugging link, but couldnt really make much sense of what it was telling me to do, and i also don't know what the voltages are supposed to be anyways :/

[Seven64]

also, with the bypass should the pedal power down when the input jack is unplugged? 

[.Mike]

i have been building circuit boards for a few years, and it never dawned on me that i could build effects pedals until a few months ago.  yes, it was a little complex, but i am very good at following directions and schematics.  i have also modded my bf-2 extensively and it sounds lightyears better.

i read the debugging link, but couldnt really make much sense of what it was telling me to do, and i also don't know what the voltages are supposed to be anyways :/

OK, so you're not totally green, which is good.

What you need to do is follow the debugging topic, and post the checklist following where it says, "Here is the checklist to fill out." You might not know what the voltages are supposed to be, but someone else here might be able to spot an error based on that information. As the debugging topic says, "Yes, it is a pain. But it is a time tested, effective, highly productive pain."

also, with the bypass should the pedal power down when the input jack is unplugged? 

Not sure what you're asking, but yeah, most pedals use the input jack to switch power on and off, and so most pedals would not power on if there was not a plug in the input jack.



Mike

[Seven64]

I just did some searching and found a list of voltages from the IC's.  Am going to start on that after i finish typing this.

I am thinking it is something with the jacks and 9v battery clip tho, because it will turn on with only a 9v AC power source and no jacks in the plugs.  The 9v battery clip isnt working either.

Here is how i have it setup:

Input jack (stereo):
Tip - to #4 of 3PDT
Ring - 9v battery neg
Sleeve - GRND

Output Jack (mono):
Tip - to #8 of 3PDT
Sleeve - GRND

3PDT Stomp Switch with Smallbear PCB
1 - Output from PCB
2 - GRND
3 - Input to PCB
4 - Tip on input stereo jack
5 - LED resistor to #6
6 - LED resistor from #5
7 - Negative side of bypass LED (LED 1)
8 - Tip on output mono jack

[Seven64]

could it be a reversed L7805?

also, the 3rd LED is always on.  is this how its supposed to be?  i thought it was a toggle for one of the spdt switches

[Seven64]

just tried it with a different 9v battery..... they bypass works, and i get very minor effects, with the time knob making some really loud and nasty sounds if it gets turned up at all.

with the 9v hooked up the circuit turns off when the input jack is unplugged.  how does this work with the battery but not the dc jack?

**edit**

rewired the D/C jack and fixed the input jack power problem.

now its just the effect that is fuxored

[Seven64]

just found i used a 35v instead of 16v electrolytic.  is this a problem?

[Seven64]

also, i used a 1pf ceramic cap at C22

Voltages.... seem WAAAAAY off according to this thread....

http://www.diystompboxes.com/smfforum/index.php?topic=77940.0

these were taken with a brand new 9v battery that read 9.02 on my multimeter.

PT2399
1 - 8.62
2 - 8.71
3 - 8.91
4 - 8.91
5 - 8.31
6 - 8.89
7 - 8.47
8 - 8.47
9 - 8.42
10 - 8.47
11 - 8.48
12 - 8.45
13 - 8.47
14 - 8.36
15 - 8.36
16 - 8.48

IC2
1 - 8.36
2 - 8.45
3 - 8.79
4 - 8.91
5 - 8.41
6 - 8.42
7 - 8.22
8 - 9.01

IC3
1 - 8.09
2 - 8.43
3 - 8.45
4 - 8.91
5 - 8.46
6 - 8.45
7 - 8.45
8 - 9.02

FET
G - 8.01
S - 8.91
D - 8.90

[Seven64]

bump, can anyone help me out?

[thedefog]

It doesn't make any sense that all of your ICs would test around the same voltage. Not to insult your intelligence, but how are you testing them with your multimeter?

Also, if you could post a few pictures of both the top and bottom of the board, that would help us out a lot. This could be anything from several solder bridges to reverse polarity parts.

Check your ground and see if you've got V+ on it.

[Seven64]

i was putting the negative side of my multimeter into the stereo input jack where the negative 9v lead was soldered, and touched the positive lead to the according place.

here are some pics of my build.  i used the little piece of PCB as a ground and to place the LED's until i had an enclosure, then i was going to re-do it.  the Red LED is the bypass, and the green is the delay tails.

it is partially taken apart for the time being (completely disconnected the bypass 3pdt switch)

[Seven64]

took another swing at it tonight.  got different voltages, then in the middle of taking them i decided to play with the pots and switches, now i am wondering how i should take measurements.  where should all the pots be?  where should the tremolo, delay tails, and mod switches be at?

[twabelljr]

just found i used a 35v instead of 16v electrolytic.  is this a problem?

No, that is fine. Maybe even a bit better.
Are any of the pot connections shorted to the pot case? Some of the look pretty close.

[Seven64]

dont think any of the pots are shorted.... and they are plastic covered.  i had to replace 2 of them cause my middle lead was too deep in the pot and was affecting how the knob worked.

here are voltages with all the pots all the way up, and all the switches "on"

PT2399
1 - 6.79
2 - 3.15
3 - 0
4 - 0
5 - 3.81
6 - 3.17
7 - fluctuating 3.0 - 3.4
8 - 2.02
9 - 3.22
10 - 3.15
11 - 3.27
12 - 2.70
13 - 3.07
14 - 3.68
15 - 3.18
16 - 3.12

IC2
1 - 3.32
2 - 3.31
3 - 3.28
4 - 0
5 - 3.29
6 - 3.39
7 - 3.46
8 - 7.81

IC3
1 - fluctuating 1.0 - 7.0
2 - 5.81
3 - fluctuating 3.0 - 5.2
4 - 0
5 - fluctuating 3.9 - 5.6
6 - fluctuating 3.9 - 5.6
7 - fluctuating 3.9 - 5.6
8 - 7.67

FET
G - fluctuating 0.3 - 0.6
S - 0
D - 0

[Seven64]

got it back together tonight, making progress.  the delay is there, but sounds really intense and a little fuzzy.  the chorus is there, and sounds cool, but the tremolo doesnt work.  gonna check my soldering job, as well as component orientation in that area.  this was with a 9v battery.

i hope my next project is easier.....

[.Mike]

One thing that leaps out at me is that your PT2399 pin 1 is at 6.79V. The absolute maximum for that pin is 6.5V.

If you take a look at the schematic, pin 1 is connected directly to the output of the 5V regulator. It should be within 5% of 5V.

I'd check to make sure you have the regulator oriented properly.

Mike

[Govmnt_Lacky]

I'd check to make sure you have the regulator oriented properly.

+1

I think Mike hit the nail on the head. 

It looks like the OUTPUT leg of the regulator needs to be closest to your PT chip. I think you have your regulator in backwards. Look here:

http://www.fairchildsemi.com/ds/LM/LM7805.pdf

Sheet 2 has an orientation.

Good Luck 

[Seven64]

heating up my desoldering iron now....

i used the L7805 instead of the LM7805, but i checked the datasheet and still think it may be backwards.  Lets hope this works!