Dirtbag Deluxe v3105 build

[mah62]

Hi folks,

When I can find I can find a suitable window and when my daughter is not jumping around my feet I need to debug my Dirtbag Deluxe v3105 build. While I'm familiar with the general procedure, having debugged several smaller circuits, this one is very daunting, to say the least! Any help or pointers, in the meantime, would be appreciated, before I get down to it.

The symptoms are as follows: audio signal disappears after C3. thereafter is a excruciatingly high pitched whine!

many thanks for any attention to this!

Here are the voltages:

supply voltage: 9.04v

IC1:    1)    4.52
           2)   4.52
           3)   4.5
           4)   0
           5)   4.48
           6)   4.53
           7)   4.53
              9.04

IC2:    1)   2.04
           2)   1.81
           3)   1.81
           4)   0
           5)   1.81
           6)   1.81
           7)   4.19
              1.81
           9)   1.81
         10)   5.19
         11)   3.98
         12)   2.35
         13)   9.04
         14)   1.8
         15)   1.8
         16)   4

IC3:    1)   4.53
           2)   4.53
           3)   4.5
           4)   0
           5)   4.51
           6)   4.53
           7)   4.53
              9.04

IC4:    1)   0
           2)   4.49
           3)   4.39
           4)   4.39
           5)   8.2
           6)   4.49
           7)   4.27
              7.93

IC5:    1)   0
           2)   4.49
           3)   4.35
           4)   4.36
           5)   8.2
           6)   4.49
           7)   4.46
              7.93

IC6:    1)   4.46
           2)   4.46
           3)   4.45
           4)   0
           5)   2.84
           6)   2.84
           7)   2.84
              9.04

IC7:    1)   1.61 <  > 7.75  moving
           2)   4.69 <  > 4.74  moving
           3)   4.69 <  > 4.74  moving
           4)   0
           5)   4.69 <  > 4.74  moving
           6)   4.69 <  > 4.74  moving
           7)   4.69 <  > 4.92  moving
              9.04

IC8:    1)   3.21
           2)   3.2
           3)   3.15 
           4)   -0.06
           5)   3.72
           6)   3.68
           7)   3.83
              7.18

IC9:    1)   3.23
           2)   3.17
           3)   3.18
           4)   7.33
           5)   7.37
           6)   7.36
           7)   -0.2
              0.05
           9)   0.05
         10)   3.23
         11)   3.16
         12)   -0.2
         13)   3.34
         14)   7.25

here are some pictures:

[mah62]

P.S. How do I get rid of those smiley faces on the last post? I'm actually a miserable bastard!

Mark

[mah62]

...oops, did I say v3105, I meant v3205 of course

Anyway, I'm on route to solving this. first thing I did was map out all the nodes on the schematic and layout using coloured paint pens. This made it a lot easier to check continuity/solder bridges. To my amazement there were none (smug mode)!





Then checked value and orientation of all the components. Getting to R41 I found the problem: I'd placed a 3k9 resistor in place of a 39k (exit smug mode, curse those 5 band resistor codes and my failing eye sight)! Eureka! Finally working!

This, as many people have found, does distort a bit, however, it has such a sweet sound. So much so that couldn't stop playing all night and ended up with a reoccurence of my tendonitis.

I'm now working through the threads regarding this on the forum and will start socketing some of the mod suggestions to see if things get a bit less fizzy.

Anyway, although it was like looking at an enormous mountain in front of me, with patience and the little colour coded system I used I actually got a perverse pleasure out of the debugging process!

Lesson learned: 1) as mentioned on this forum by Midwayfair, amongst others, always use your DMM not your eyes to verify parts. 2) Take your time 3) drink lots of tea/coffee 4) don't despair, never give up!

Mark