Java boost popping and scratching: where to debug? - SOLVED

[barret77]

Hello all

Java Boost, my problem child. A simple effect, but I don't know why it's giving me so much trouble.
It works right now, but it's not usable:
- the guitar volume pots get *scratchy* making lots of noise when moved and the pedal is on. I guess everyone agrees that this is a DC being fed to the guitar symptom...
-it pops *loud* when activated/deactivated... but torchy's layout, the one I'm using, has pull down resistors to avoid it already...

I'm quite lost. Where should I look for this kind of trouble in this circuit?

I'm a bit suspicious of the off board wiring, since I always get confused on positive ground. But I found nothing special there...


Thanks for any hints and tips!

[Kondor]

You might try squirting some contact cleaner down the shaft, it could be dirty and that might be what's making it "scratchy".  The popping when you turn it on/off should not happen using pull down resistors.  What resistors are you using and how did you wire them on your build?

[barret77]

Hi

Sorry for not explaining it well...
The guitar pots become scratchy only when the effect is on; when it's bypassed it returns to normal, being not a case of cleaning...
The pulldown resistors are at Torchy's layout - they're 1M instead of 2M2 as RG used on the Treble Blaster.

I'm really confused: Is Torchy's Java Boost layout positive or negative ground after all?

Here's the layout:

[hairyandy]

The Java Boost is negative ground.  The first place I'd check is to make sure you have the proper cap values.  Torchy used a mix of uf and nf to notate them (those darn Brits!  ) so it might be that you got one or two wrong.  That could explain the DC on the guitar volume if you used the wrong output cap maybe (C4)?  Also,  pulldown resistors don't always work, in my experience.  Try turning it off and on a few times to see if that helps.

[rockgardenlove]

The pot scratch is normal with all rangemasters. 

[barret77]

Got the problem - I rewired it as neg. ground.

Is there any tranny biasing reference for negative ground? the values are not the same from the positive one...

[Kondor]

Glad to hear you got it fixed!