Current Not Loving - Sorted

[alanp]

I'm using a MN3207 (kinda wish I hadn't now). Signal gets through on the output, but no flanging happens at any point in the bias. Audio probing pins 7 and 8 of the BBD while slowly adjusting bias yields no signal at all. I am getting guitar signal on pin 3, though, so it is getting into the BBD.

Pin 4 on IC2 was 8.0V initially, and the build doc states it should be 7.6 to 7.7. I daisychained another 1n914 onto D4.

IC2 MN3207
1 0V
2 4.45V
3 signal
4 7.70
5 8.26
6 4.47
7 3.37
8 3.40

IC4 4013
1 4.48
2 4.48
3 8.7 to 7.1 slow oscillation
4 0
5 4.48
6 0 to 0.3
7 to 12 inclusive 0volt
13 8.96
14 8.96

IC 3 4049
1 8.96
2 4.3 - 4.6 slow oscillation
3 4.3 - 4.6 slow oscillation
4 0
5 4.8
6 4.7
7 4.7
8 0
9 4.7
10 4.7
11 4.7
12 4.7
13 0
14 4.8
15 4.8
16 0

[alanp]

I spent a bit more time with it today. All the resistors and caps are the correct values, as far as I can see.

I tried adjusting the clock trimmer as well as the bias today. At some points, I get a high pitched whistle out of pins 7 and 8 on the BBD that dip into and out of hearing range, at roughly 1 or 2 Hz.

Can anyone tell me if the MN3207 is likely to be bad?

[Scruffie]

Voltages look okay... whine is normal that's the clock signal.

Is your LFO actually moving? What's your 311 voltages.

It's possible the 3207 is bad, where'd you get it from and did you use ESD protection when handling it?

[TheCobbenator]

I'm in the exact same boat.

When I went through mine with a scope with my engineer friend, we came to the conclusion I may have killed the 3207 with static. Now I have to decide whether to get a new 3207 or just convert it to 3007. At this point, i'd almost rather do the latter.

[alanp]

I got the 3207 from Smallbear. It arrived in a plastic ziplock bag with no foam to protect the legs, and no silver ESD bag. These things can get damaged, then?

IC6 311
1 0
2 1 - 3.59 slow osc.
3 0.95 - 2.35 slow osc.
4 0
5 8.95
6 8.96
7 6.1 - 8.6 slow osc.
8 8.96

The moving voltages were around 1 to 3 Hz.

[Scruffie]

I'm in the exact same boat.

When I went through mine with a scope with my engineer friend, we came to the conclusion I may have killed the 3207 with static. Now I have to decide whether to get a new 3207 or just convert it to 3007. At this point, i'd almost rather do the latter.

Why... the 3007 is just as static sensitive and the 3207 is cheaper and easier to get a working one.

I'll check your 311 voltages when i'm not just back from the pub alanp.

[TheCobbenator]

You right. Because if I even began to know what I was talking about, I would have finished this project 5 months ago!

[alanp]

New 3207 arrived yesterday from SB. I ordered a v3207 this time.

IT HOBBLES! The MN3207 was munted, it looks like.

That said, all I've got out of it so far is the world's weirdest oscillator.



I've tried playing with the clock and bias, and all it'll pass is an odd oscillation that changes if I muck around with the trimmers. Strumming the guitar does nothing. If I ground the input with my hand on the end of the guitar cable, the oscillation changes. Pin 1 of IC1 has the guitar signal, and Pin 7 has the oscillation.

[alanp]

Got it -- some solder bridges around IC6, combined with T1 trimmer acting decidedly oddly (stuck passing everything) for a little bit.

She's a right beaut right now. And you can get some truly odd noises out of her...

[TNblueshawk]

Oooo, I'm happy for you. Congrat's.