Q-vibe Problem !

[Jimihendrix1987]

Hi there,

I bought this PCB from the Great B long time ago, however I couldn't started with it since now. Today I've just finished it...

Problem? Only Bypass sound.

I've already checked the wiring around 5 times... But i don't know wtf it's happening... The lamp shines as it should and it vibes when I adjust the trimpots, also the intensity and the speed knobs (Outside LED does the same). So I think the modulation issue is solved...

Here are the voltages reading, I hope you could give me 10 hands

Q1 (J201). D = 17v / S = 0v / G = 0v
Q2 (BC549c). C = 8.9v / B = 1.6v / E = 1.8v
Q3 (BC549c). C = 6.7v / B = 2.6v / E = 2.2v
Q4 (MPSA13). C = 17v / B = 3.1v / E = oscillation between aprox 0 and 9v
Q5 (MPSA13). C = 8.1 - 9.8v / B = 3.5 - 3.8v / E = 2.7 - 2.4v





There's almost nothing written about q-vibe...

I'm really looking forward to hearing from all of you, great builders  

Ignacio

[madbean]

Q1 Source appears to be a problem. Check for grounds there, and audio probe these two points:

Q1 gate to verify you have input signal
Q2 base and collector to verify you have output from Q1 and Q2.

[Jimihendrix1987]

Wow ! Solved !!!

It was a little piece of soldered jumper between q1's source and the ground...

Now it is working ! And how it works !!! Sweet vibrato machine 

Tomorrow I'll play with the trimpots a little bit, trying to get the best of this machine out.

On the other hand, I think we ought to improve the switch noise it produces between vibe and tremolo.

Is it possible to include a pull down 1 M resistor? Where?

Thanks Don Brian ! (in some Spanish villages, people used to call DON to wisemen )

[Jimihendrix1987]

Can anyone answer this question ?

On the other hand, I think we ought to improve the switch noise it produces between vibe and tremolo.

Is it possible to include a pull down 1 M resistor? Where?

Thanks

[Jimihendrix1987]

Can anyone answer this question ?

On the other hand, I think we ought to improve the switch noise it produces between vibe and tremolo.

Is it possible to include a pull down 1 M resistor? Where?

Thanks

Eooo ! Has anyone suffered from a POP Noise everytime you wanted to switch between Vibrato and Tremolo mode ?

This POP Noise is exactly the same as you ear when you turn on your Rangemaster without a Pull-down resistor...

What can I Do?

Thanks