Dirtbag v3205 problems

[HHR18]

Hi there,

I'm having trouble getting my Dirtbag to work. With all the controls maxed, there is barely any sound coming from the pedal and no delay is noticeable. Here are the voltages, hope someone can point me in the right direction!

Power supply voltage = 9.32v

IC1 - TL072
1   4.65
2   4.30
3   4.43
4   0
5   4.23
6   4.65
7   4.67
8   9.32

IC2 - NE570
1   1.30
2   1.80
3   1.80
4   0
5   1.81
6   1.79
7   7.89
8   1.81
9   1.81
10   6.69
11   4.48
12   1.81
13   9.32
14   1.80
15   1.80
16   0.03

IC3 - TL072
1   4.65
2   4.65
3   4.43
4   0
5   4.50
6   4.65
7   4.65
8   9.32

IC4 - v3205
1   0
2   4.67
3   2.98
4   2.98
5   8.14
6   4.68
7   3.56
8   0.03

IC5 - v3205
1   0
2   4.67
3   3.24
4   3.25
5   8.13
6   4.67
7   4.20
8   0.06

IC6 - TL072
1   4.20
2   4.20
3   4.08
4   0
5   5.19
6   5.36
7   5.36
8   9.32

IC7 - TL062P
1   fluctuates (3.85 - 5.71)
2   4.72
3   fluctuates (4.70 - 5.00)
4   0
5   fluctuates (4.71 - 4.77)
6   4.56
7    fluctuates (4.67 - 4.89)
8   9.32

IC8 - TL072
1   4.66
2   4.66
3   4.51
4   0
5   6.07
6   6.68
7   6.67
8   9.32

IC9 - CD4047BCN
1   4.30
2   4.98
3   4.98
4   9.32
5   9.32
6   9.32
7   0
8   0
9   0
10   4.67
11   4.67
12   0
13   4.35
14   9.32

[gtr2]

Your best bet is to work through the schematic/pcb with an audio probe starting at the input.  See where you are loosing signal.

Josh

[HHR18]

Got it, just tried it, when I probe pin 7 on IC4 I get (distorted) sound, when I probe pin 3 and 4 on the same IC I don't get any sound. Just swapped IC4 and 5 around and had the same problem so I don't think it's the 3205s that are the problem.

[Scruffie]

Your problem is the BBDs, no voltage on Pin 8 of either, you've missed a jumper, put the diode backwards, something a long those lines. Rest looks fine.

[HHR18]

Ok still no sound but my voltages on the v3205s changed, are these good values?

IC4 - v3205
1   0
2   4.70
3   4.70
4   4.70
5   8.15
6   4.70
7   6.97
8   7.78

IC5 - v3205
1   0
2   4.70
3   7.75
4   7.75
5   8.15
6   4.69
7   8.15
8   7.78

[Scruffie]

Better, bias is set way too high on both though, hopefully that solves the high outputs on IC5 and it's not another issue.

[HHR18]

I had the trimpots on max so that could explain the high voltages, here are some new ones, it's still not working and my audio probe tells me the problems has something to do with the BBDs:

IC4 - v3205
1   0
2   4.70
3   4.65
4   4.65
5   8.14
6   4.70
7   4.07
8   7.77

IC5 - v3205
1   0
2   4.70
3   4.66
4   4.68
5   8.14
6   4.70
7   4.18
8   7.77

Further tips would be greatly appreciated!

[HHR18]

Oh I forgot to tell you, I have input on pin 7 of IC4, but pins 3 and 4 don't give me any delayed signal!

[madbean]

Are you positive you have used 100k for both the bias trimpots?

[HHR18]

Yes, absolutely positive

[HHR18]

Should I buy some new v3205s or might something else be the problem?