First amp project problems :(

[Katier]

Had a go at building the Ruby http://www.runoffgroove.com/ruby.html and she doesn't want to work..

In the absence of anything more than a volt meter I guess I'm stuffed when it comes to fault finding?

[Roly]

You can actually do a lot with a multimeter, well ... enough, anyway, the rest is done in your head.



What voltage is is on the battery, the supply rails on the build, actual pins 4 and 6 on the actual chip?

What is the voltage on pin 5?

What is the voltage across the 3k9 in the FET Source?

In the meantime use a screwdriver or scriber to make sure all solder joints are connected only where they should.  Forget to cut a track, put in a link?

[joecool85]

When you say it doesn't work, what is it doing?  Nothing at all?  Low volume?  Weird noises?  Chip getting hot?

[Katier]

yey she works!!!

I think I was driving too much power into her off the PC when testing.. lowered the input volume (as the input voltage was significantly higher than a suggested guitar voltage) and she worked straight away.

Usable volume although does really need fully turning up with the hifi speaker I'm using.

[Katier]

When you say it doesn't work, what is it doing?  Nothing at all?  Low volume?  Weird noises?  Chip getting hot?

She is a bit crackly but I think that's just noise from when I touch the case of the pots to adjust them ( for instance ) - is it worth/good idea to ground the pot cans to earth?

[Roly]

is it worth/good idea to ground the pot cans to earth?

Yes.  These are normally grounded somehow in almost all equipment.

Get it mounted in a case of some sort, biscuit tin, diecast hobby box...

[Katier]

I'm mounting it all inside an old hi-fi speaker now it's working. I know hi-fi speakers aren't ideal but for this little project should work fine. I'll solder wire to the pot cans and then to the zero volt rail.

She's running off a 12V transformer feed btw, I have loads of transformers so easier than messing with batteries!!