Clarifications on NeoVib PCB & debugging

[sammy]

hi Folks,
I've completed my NeoVibe (geoflex with General Guitar Gadget PCB) but I can't seem to get it working

I have the Lamp, Speed, Depth working fine.
Bypass works fine too, but that's about all.

I started the debugging process and so far I'm getting volts across all the areas that the GEOFlex schematics recommend,
I have 15volts across the power rail. (as expected) but the rest are usually higher than recommended.

I'm after confirmation that I'm doing the checks correctly.

I have the wall transformer's positive power source (red) coming in on Pad 'K' and the negative (black) on 'J'.

Is this correct?

When I debug, If I put the black Multimeter probe on Pad 'O', I get the expected voltage readings. If I put it on 'J' , the readings are a couple of volts higher.

What is pad 'O' for? The schematic doesn't mention anything

[R.G.]

I have the wall transformer's positive power source (red) coming in on Pad 'K' and the negative (black) on 'J'.
Is this correct?

You don't say, but I'm reading into this that you are using a wall adapter that has a DC output, not an AC output. It has to be this way if it has a positive and a negative lead.

When I debug, If I put the black Multimeter probe on Pad 'O', I get the expected voltage readings. If I put it on 'J' , the readings are a couple of volts higher.
What is pad 'O' for? The schematic doesn't mention anything

Pad O is a signal ground point. The schematic shows it connected to signal ground, which is symbolized by the little down-pointing triangle.

It is one of the correct places to connect your multimeter negative lead. Pad "J" is NOT a correct place to connect a multimeter lead; it is separated from the true signal ground potential by the diode bridge which is there to rectify the AC which was what the original power supply provided.

[sammy]

Hi everyone & R.G
I'm Still having problem trying to get the NeoVib e to work.
I haven't made any progress and I'm starting to feel like I'll never get this working ....  
The Bulb circuit seems to work fine.
The bulb flashes, the Speed and  Depth control works fine.
It s the rest of circuit that I'm having problems with.
I searched around the web and found that the General Guitar Gadgets PCB has a fault with the silk screen print showing c16 polarity the wrong way around .
I turned it around but it still does work.
In the image, I have yellow bubbles where I have indicated the voltages I'm getting.
I'd like to know if these are ok and  what  I should be getting in the yellow bubbles marked  A,B & C.

I have the right voltage on the pos side of c17 but nothing on the neg. Is this right?
I thought c17 was faulty and replaced it but NBG.

I have checked the polarity on caps and that are all ok, and I can;'t see any dry solder , so any advice or help on what els eI should do would be very much appreciated

Following is an image of the schematics and the voltages I'm getting.



Thanks in advance
Sam

[R.G.]

I haven't made any progress and I'm starting to feel like I'll never get this working ...

Just to put this into perspective, you clearly haven't done this for a few weeks day in and day out (and well into the night, too) with your boss looking over your shoulder and demanding written progress reports. Believe me, the situation could be a lot worse. 

The Bulb circuit seems to work fine.
The bulb flashes, the Speed and  Depth control works fine.

That's important. Dividing what works from what does not work is a huge part of debugging.

In the image, I have yellow bubbles where I have indicated the voltages I'm getting.
I'd like to know if these are ok

Yep, they look OK.

and  what  I should be getting in the yellow bubbles marked  A,B & C.

All should be zero volts, plus or minus a few millivolts.

I have the right voltage on the pos side of c17 but nothing on the neg. Is this right?
I thought c17 was faulty and replaced it but NBG.

Actually, you have zero on the negative side. Zero is a voltage, and in this case is the correct and necessary one.

I have checked the polarity on caps and that are all ok, and I can;'t see any dry solder , so any advice or help on what els eI should do would be very much appreciated

Make and use an audio probe if you don't have access to an oscilloscope. Follow the signal from the input pad through the circuit, looking at the collector and emitter of Q3, then bases of Q4, 6, 8, 10 and the emitters and collectors of Q5, 7, 9 and 10. When the signal stops, something before there was stopping it and needs to be fixed.

[sammy]

I T   L I V E S !!!!!

Very grateful for your help R.G, the probe worked a treat.
Turns out I had the stomp switch wired wrong 

Thanks again
Sam

[R.G.]

Congratulations!

I can't tell you how many stomp switches I've wired wrong.  It's part of the learning.

Now go make LOUD noises! 

[Beo]

RG, I think sometime last year you had a NeoVibe layout that you were testing out which was small enough to fit in a Wah enclosure. Did that ever get verified, and might it become available? I finally have a UV setup for tight layouts.

[Mich P]

Beo wrote :

"RG, I think sometime last year you had a NeoVibe layout that you were testing out which was small enough to fit in a Wah enclosure. Did that ever get verified, and might it become available? I finally have a UV setup for tight layouts."

+1

Mich P.