Yes, yet another neovibe debug topic

[Valoosj]

1.Neovibe
2.I followed the layout from the write-up.
3.Mods: 250K trimmer replacing the 2 100K resistors, added a 100K trimmer in series with R47.
4.The vibe vibes, but I get this background noise. Listen to it here neovibe;k.mp3


Some pics:



I'm using 18VDC, in the meantime I pulled out the diode bridge, as my previous neovibe did not have it and that on did work fine.


All trannies 2N5088 apart from the bulb trannie, that's a 2N3904.

I will update this tonight with the voltages on the trannies, but maybe somebody already has an idea by the sound.

[MikeH]

When I try to listen to that clip I get "Access Denied!"

[Valoosj]

That should be fixed now.
As for the voltages, I don't know if they will be necessary, seeing as the vibe really works well apart from the extra noise.

[MikeH]

Heh heh- are you sure that just isn't a hamster running on it's wheel in the background? 

As far as what might be wrong; sorry, I got nothin'

[Valoosj]

Might also be good to know, I'm turning the speedknob in the beginning.

[mdh]

Maybe it's those long wires going from the neighborhood of the lamp driver over to the little daughterboard.  If they have a pretty hot LFO signal on them (which I suspect they do), it's easy to imagine that it's getting capacitively coupled into the audio path.

[Valoosj]

Ok, voltages!

7815 gives out 14,70V

Q1
C 1,8
B 1,3
E 0,9

Q2
C 4,25
B 1,8
E 1,5

Q3
C 10,9
B 4,25
E 3,6

Q4
C 14,75
B 4,66
E 4,25

Q5
C 11,1
B 4,66
E 3,6

Q6
C 14,75
B 4,66
E 4,25

Q7
C 11,1
B 4,66
E 3,6

Q8
C 14,75
B 4,66
E 4,25

Q9
C 11,1
B 4,66
E 3,6

Q10
C14,75
B5,85
E5,4

Q11
C 18,10
B 6-8 (can't get a stable reading and it shifts so fast)
E 8-11

Q12
C 18,10
B 8-11
E 7,5 - 10,2

Q13
C 14-18
B 1-3
E 1-2

[Valoosj]

Maybe it's those long wires going from the neighborhood of the lamp driver over to the little daughterboard.  If they have a pretty hot LFO signal on them (which I suspect they do), it's easy to imagine that it's getting capacitively coupled into the audio path.

Those 3 trimmers are for the mods. The mixing resistors, the extra 100K to R47 to change the sweep a bit, and the pulsating led mod. At first there was no LED, but the sttrange noise was there though. Adding the LED didn't change it.


EDIT: I just removed the R47 mod, still no improvement.

[SteveB]

Wow! I wish I could help, but I all I know is that something is definitely wrong. The guitar sound should be modulating more, & the feedback squeak shouldn't be there at all. Check solder joints, cap polarities & resistor values.

Steve

[Valoosj]

Could my powersupply be causing this? Or is the on board filtering sufficient?

[Valoosj]

Is there somebody that can check the voltages?
Or shoot out some ideas?

[Valoosj]

Ok, I think I already found out. I hooked my power supply up to my OCD, and the bugger starts making the same type of noise, only the oscillation goes a lot faster. Safe to say that it's the power supply then that causes the noise. Will try with another one shortly.