Howdy friends -
I'm finishing up my second Dirtbag, and I'm not getting any delay whatsoever. The "Level" control is functional (with clean signal), but from what I can tell with my probe, my signal is not making it to the MN3005s. I know that my chips are good (tried them in my other Dirtbag, which works), and visually everything on the board checks out against my functional build. The only difference I can see is that I used TL072CPs here and TL072CNs on the other.
Where should I be looking for a signal drop? I've tried tracing via the instructions and I keep getting lost/frustrated. Any help would be appreciated. Thanks!
You should start with... Voltages!
Can do! Which chip?
Quote from: eldanko on February 19, 2012, 02:08:12 AM
Can do! Which chip?
All of them would be the best way to go about it, I know it's a hassle but it helps to gauge the area alot of the time.
Dane,
Here is my working voltages from another post...
The input voltage is 14.75V. I omitted IC7 since thats the modulation section.
Josh
IC1
1) 7.14
2) 7.14
3) 7.12
4) 0
5) 7.07
6) 7.14
7) 7.14
8 ) 14.74
IC2
1) 1.18
2) 1.78
3) 1.78
4) 0
5) 1.78
6) 1.78
7) 10.12
8 ) 1.78
9) 1.78
10) 7.73
11) 6.02
12) 1.78
13) 14.74
14) 1.78
15) 1.78
16) 0
IC3
1) 7.14
2) 7.14
3) 7.12
4) 0
5) 7.12
6) 7.14
7) 7.14
8 ) 14.74
IC4
1) 14.7
2) 7.29
3) 6.28
4) 6.27
5) 0
6) 7.29
7) 7.82
8 ) 0
IC5
1) 14.7
2) 7.29
3) 7.33
4) 7.33
5) 0
6) 7.29
7) 8.94
8 ) 0
IC6
1) 8.95
2) 8.83
3) 8.8
4) 0
5) 6.96
6) 6.98
7) 6.83
8 ) 14.74
IC8
1) 7.14
2) 7.14
3) 7.12
4) 0
5) 7.66
6) 7.73
7) 7.73
8 ) 14.74
Alright, here we go. I included all ICs for the sake of being thorough. Input voltage is 14.7.
IC1
1) 8.6
2) 8.6
3) 8.6
4) 0
5) 8.5
6) 8.6
7) 8.6
8) 14.7
IC2
1) 1.0
2) 3.2
3) 3.2
4) 0
5) 2.6
6) 2.6
7) 13.9
8) 3.3
9) 3.1
10) 13.9
11) 10.9
12) 3.1
13) 14.7
14) 3.1
15) 3.1
16) 0
IC3
1) 8.6
2) 8.6
3) 8.6
4) 0
5) 8.6
6) 8.6
7) 8.6
8) 14.7
IC4
1) 14.7
2) 7.2
3) 7.0
4) 7.0
5) 0
6) 7.2
7) 8.2
8) 0
IC5
1) 14.6
2) 7.2
3) 7.1
4) 7.1
5) 0
6) 7.2
7) 8.2
8) 0
IC6
1) 8.2
2) 8.2
3) 8.2
4) 0
5) 9.4
6) 9.4
7) 10.3
8) 14.7
IC7
1) Varies
2) 7.5
3) Varies
4) 0
5) 7.5
6) 7.5
7) Varies
8) 14.7
IC8
1) 8.6
2) 8.6
3) 8.6
4) 0
5) 13.7
6) 13.9
7) 13.9
8) 14.7
IC9
1) 7.9
2) 6.7
3) 6.8
4) 14.7
5) 14.7
6) 14.7
7) 0
8) 0
9) 0
10) 7.2
11) 7.2
12) 0
13) 7.9
14) 14.7
There you have 'em. The only thing my untrained eyes noticed was that I had much higher voltages on lugs 5-7 of IC8 than you did, Josh. So... you guys see anything?
Side note: now I see why you had a space in your "8 )" in each list...
Quote from: eldanko on February 19, 2012, 07:28:56 PM
Side note: now I see why you had a space in your "8 )" in each list...
So... those readings aren't just cool? ;D
IC8 is looking bad on the output post NE570, voltages are far too high for pins 5,6 & 7
NE570 voltages are a bit odd too... look around there for wrong values, solder bridges etc.
After re-checking all of my resistors and solder joints, I decided to try swapping in the NE570 from my other Dirtbag... it worked. Looks like I got a bad NE570 chip. Got it biased up now, and it sounds killer with the exception of some nice lo-fi clock noise at the longest delay setting. That's normal, yes? Either way, I'm happy - it's giving me longer times than my other Dirtbag.
Thanks for the help in narrowing that down fellas.
I did have to troubleshoot my dirtbag and fought with a bad ne570 as well.
Do you mind sharing where you ordered it from?
It was an NOS Philips from SmallBear. The other one I got from there was good, as was the spare that I swapped in after discovering the failure.
Mods: If sharing that isn't cool, feel free to edit/whatever. No ill will towards SBE... :D
Glad you got it solved!
Josh