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DIY Stompboxes => Building your own stompbox => Topic started by: Mecha Money on August 16, 2011, 10:41:19 PM

Title: Vox Tone Bender Transistor problem - please help!
Post by: Mecha Money on August 16, 2011, 10:41:19 PM
okay. so i'm building a vox tone bender from the schematic linked below.

everything seems to be wired properly and i get clear sound on true bypass. when i click on the effect i get nothing (but the LED lights up - my only mod to the schem - aside from 3pdt true bypass)  as per Geofex debugging page i made the measurements, and tried resoldering all the connnections to the troubled transistor.  the link below shows the schematic i'm using plus the values i got from metering the transistors. It seems one of them is saturated.

does this mean my transistor is fried, or am i possibly overlooking a short somewhere. I am considering breaking this down and starting over from scratch, but i feel like i've isolated the problem to this transistor.

thoughts?

Thanks!

(http://www.flickr.com/photos/35416785@N05/6051196899/)


http://www.flickr.com/photos/35416785@N05/6051196899/ (http://www.flickr.com/photos/35416785@N05/6051196899/)


Title: Re: Vox Tone Bender Transistor problem - please help!
Post by: aron on August 16, 2011, 10:45:53 PM
Check out the debugging page. Your problem is probably a simple mis-wiring.
Title: Re: Vox Tone Bender Transistor problem - please help!
Post by: LucifersTrip on August 17, 2011, 07:39:30 AM
There is a mis-wiring, short of some type or you hooked up the power incorrectly. Q1's emitter is grounded so voltage should be 0 (not 9.13) ...and all readings should be negative

you see that this is pnp, positive ground?
Title: Re: Vox Tone Bender Transistor problem - please help!
Post by: Mecha Money on August 18, 2011, 10:17:01 AM
thanks for the input gang. I do have the power wired correctly for positive ground (or so I believe I do!)

great info re Q1 voltage readings.. looks like I'll be going through this puppy step by step. in this instance - given the small amount of components, would you recommend doing a complete rebuild, or just retrace your steps and make the connection corrections where necessary?

thanks again!
Title: Re: Vox Tone Bender Transistor problem - please help!
Post by: R.G. on August 18, 2011, 10:25:32 AM
Read and follow "Debugging: what to do when it doesn't work".