Dirtbag MN3205 - Powered at 9v - No delay !

[Jimihendrix1987]

Hi folks,

Just finished my Dirtbag powered at 9v. I payed attention to every solder I made (because of the high level required to do this kind of project) but I haven't been able to make it work properly.

The guitar sounds with the effect engaged although can't get the delay sound. Pin 3 of IC4 and IC5 does not response to the audio probe signal.

Think it looks quite good:



Hope you can help me to run it !

Voltages:

IC 1
1 - 5.20
2 - 5.20
3 - 5.10
4 - 0
5 - 4.73
6 - 5.20
7 - 5.20
8 - 9

IC 2
1 - 6.51
2 - 6.72
3 - 6.72
4 - 0
5 - 7.64
6 - 7.54
7 - 8.3
8 - 6.88
9 - 6.88
10 - 8.35
11 - 7.79
12 - 6.45
13 - 9
14 - 7.15
15 - 7.15
16 - 6.45

IC 3
1 - 5.20
2 - 5.20
3 - 5.11
4 - 0
5 - 5.04
6 - 5.21
7 - 5.21
8 - 9

IC 4
1 - 0
2 - 9.04
3 - 4.25
4 - 4.36
5 - 8.11
6 - 9.04
7 - 7.49
8 - 7.75

IC 5
1 - 0
2 - 9.04
3 - 3.79
4 - 3.87
5 - 8.11
6 - 9.03
7 - 7.12
8 - 7.75

IC 6
1 - 6.10
2 - 6.06
3 - 5.94
4 - 0
5 - 5.49
6 - 5.66
7 - 6.12
8 - 9.04

IC 7
1 - 4.38 - 5.14 (Oscillating)
2 - 4.73
3 - 4.77
4 - 0
5 - 4.73
6 - 4.78
7 - 4.76
8 - 9.04

IC 8
1 - 5.20
2 - 5.20
3 - 5.05
4 - 0
5 - 7.59
6 - 7.63
7 - 8.35
8 - 9.04

IC 9
1 - 9.04
2 - 0
3 - 0
4 - 9.04
5 - 9.04
6 - 9.04
7 - 0
8 - 0
9 - 0
10 - 0
11 - 9.03
12 - 0
13 - 0
14- 9.04

Looking forward to hearing from all of you Masters

Ignacio
14

[madbean]

Do you have audio at pin7 of IC4 - the input to the first BBD?
Are you sure your MN3005 are good?
What values did you use for R11 and R12? If you are running it at 9v, you may need to lower the values.

[Jimihendrix1987]

Hi Bean !

Apologise me for my mistake. I'm not using 3005... They are MN3205, supposed to be originals ( bought them from a trusty dealer)

R11 and 12 both are 47k. No signal in pin 7 IC4.

Only signal in pin 3 and 4 IC 5 when the level is fully clockwise and the bend pot is fully counterclockwise. The Blend pot works as a strange kind of volume pot. When it is fully clockwise the effect does not sound, when it is fully counterclockwise the effect is more gainy !

Neither work the modulation led.

And Yes the signal of my audio probe does enter by the IN pad into the PCB. Cheking the fx with the output to the Amp and the input signal as my audio probe despite of the guitar.

Going to recheck EVERYTHING.

Thanks

Ignacio

[madbean]

Okay, no signal in pin7 of IC4 is the beginning of the problem. You need to check the audio path to see where the signal drops off.

Start here:
pin1 IC1
pin6 IC2
R13
pins7 IC6

[Scruffie]

IC 9 the 4047? Clocks not working. Need approx half supply on pins 2&6 of the BBDs.

[Jimihendrix1987]

Everything rechecked.

Had a wrong resistor in r54. Just replaced and still
Can't delay the fx.

No signal in ic4 with audio probe. Very low Signal in pins 3 and 4 of Ic5.

No signal in pin 1 Ic1. Signal in pin 2 Ic1 (as loud as heared at input fx pad)

Very low signal at r13.

No signal in pin6 IC2 and pin7 Ic6.

What the hell is going on? I'm pretty sure that everything is well soldered in the right place. 

Waiting for your answer ! Thanks

[Jimihendrix1987]

Hi again !

After a large holidays I'm here again ... I have reviewed every component, every resistor and they are all soldered in the right place. I have re-done every solder but It still doesn't work properly...

Nevertheless, the IC voltages have changed. Here is what I get (in blue the new voltages / in white the voltages i got last time i checked everything )

IC 1
1 - 5.20
2 - 5.20
3 - 5.10
4 - 0
5 - 4.73
6 - 5.20
7 - 5.20
8 - 9

IC 2
1 - 6.51
2 - 6.72
3 - 6.72
4 - 0
5 - 7.64
6 - 7.54
7 - 8.3
8 - 6.88
9 - 6.88
10 - 8.35
11 - 7.79
12 - 6.45
13 - 9
14 - 7.15
15 - 7.15
16 - 6.45

IC 3
1 - 5.20
2 - 5.20
3 - 5.11
4 - 0
5 - 5.04
6 - 5.21
7 - 5.21
8 - 9

IC 4
1 - 0
2 - 9.04 . 4.21
3 - 4.25 . 6.24
4 - 4.36 . 6.4
5 - 8.11 . 8.14
6 - 9.04 . 4.14
7 - 7.49 . 4.02
8 - 7.75 . 7.79

IC 5
1 - 0
2 - 9.04 . 4.16
3 - 3.79 . 4.43
4 - 3.87 . 4.45
5 - 8.11 . 8.14
6 - 9.03 . 4.20
7 - 7.12 . 1.29
8 - 7.75 . 7.79

IC 6
1 - 6.10 . 1.29
2 - 6.06 . 1.23
3 - 5.94 . 0.9
4 - 0
5 - 5.49
6 - 5.66
7 - 6.12
8 - 9.04

IC 7
1 - 4.38 - 5.14 (Oscillating) . 0.79 - 8.4 (Oscillating)
2 - 4.73 . 4.63
3 - 4.77 . 4.15 - 5.25 (Oscillating)
4 - 0
5 - 4.73 . 4.60
6 - 4.78 . 4.73
7 - 4.76 . 4.21 - 5.07 (Oscillating)
8 - 9.04

IC 8
1 - 5.20
2 - 5.20
3 - 5.05
4 - 0
5 - 7.59
6 - 7.63
7 - 8.35
8 - 9.04

IC 9
1 - 9.04 . 4.83
2 - 0 . 4.19
3 - 0 . 4.18
4 - 9.04
5 - 9.04
6 - 9.04
7 - 0
8 - 0
9 - 0
10 - 0 . 4.15
11 - 9.03 . 4.18
12 - 0
13 - 0 . 4.86
14- 9.04

Checking with the audio probe I:
- Don't get signal in Pin 3 IC4, Pin 7 IC4 neither Pin 7 IC6.
- Get very low signal in Pin 6 IC2 and R13.
- Get very low NOISE pin 1 IC1

Please folks help me out with this madness !

Ignacio

[Jimihendrix1987]

Is there anybody out there? (very good Pink Floyd Delayed theme)


I want this one working but I'm empty of ideas. Anyone?

Thanks in advance

Ignacio

[Scruffie]

Well good news is your clock voltages look much better... little off but let's assume they're working.

Checking with the audio probe I:
- Don't get signal in Pin 3 IC4, Pin 7 IC4 neither Pin 7 IC6.
- Get very low signal in Pin 6 IC2 and R13.
- Get very low NOISE pin 1 IC1

Right, well if we go from the start, IC1 Pin 1, low signal here is bad unless you've got the level control turned down... could be a bad level pot, if there's poor signal coming out here the rest of the circuit isn't gunna have much to work with.

I'm a little concerned with your voltages, it seems your V.Ref is a little bit high on all your opamps considering your supply voltage, check the values of R59, R60 & C48 (plus its polarity).

Ignore IC4 & 5 for now untill you have good signal going through IC1 and following that IC6.

Considering your reflow got the LFO & Clock to start ticking maybe you should do some reflows round the areas of those ICs, may still have bad joints.

A photo of the board may be of use.

[Jimihendrix1987]

Thanks Scruffie,

It is important to know that Although I've got troubles with the signal at IC1 Pin1, the FX sounds however it doesn't delay the signal nor modulate it.

The strange thing here and what I concern about is that I can't explain why I don't get any sound (only very Low NOISE) at pin 1 IC 1 when the fx is engaged but it is working. It's working because it modifies the bypass signal and I can lower it by using the level and bend pots !

The other pots doesn't work.

Pictures:





As I said... I rechecked every component and solder once !

[Jimihendrix1987]

Damn thing !

I can't explain why the signal sounds through the pedal when it is switched on whereas I only get very LOW noise in pin 1 of IC1.

Anybody?

I guessed the fx won't sound unless I got sound in pin1 IC1...

Why?

[Scruffie]

Have you tried replacing IC1?

It's either IC1 is bad, or you have a bad solder joint, short or something nearby pulling it down.

[Jimihendrix1987]

Haven't tried, but it's a good solution...

I'll give it a a try, hope it works...

Besides, I still can't explain why it sounds when the fx is engaged even though I only get noise on IC1 !