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madbeanpedals::forum

Projects => General Questions => Topic started by: AJPennypacker on January 27, 2016, 01:23:39 AM

Title: Mangler, first build, odd Bias voltage reading - help pls
Post by: AJPennypacker on January 27, 2016, 01:23:39 AM
Hi all, built the PNP Mangler, it works (after a few fixes) but when trying to bias my voltage reading on the pad is btwn -.23 and -.14 can't get it to -4.5, any help appreciated.
Title: Re: Mangler, first build, odd Bias voltage reading - help pls
Post by: madbean on January 27, 2016, 01:34:06 AM
Possibly you have used a wrong value for R3 or R4. It should be 220R and 470R, resp. What color are the bands on your R3 and R4 resistors? Also, did you use the 20k trimmer, or a different value?
Title: Re: Mangler, first build, odd Bias voltage reading - help pls
Post by: AJPennypacker on January 27, 2016, 02:00:20 AM
Used a 20k trimmer, upped the R4 to 1k to increase volume (as per another post). R3 is 24k; came with the PNP's, indicated as the correct R3 for those transistors which now seems a bit extreme considering it should be 220R. I'll swap it for a 220 and see if that clears it up.

Thanks for the help

Title: Re: Mangler, first build, odd Bias voltage reading - help pls
Post by: AJPennypacker on January 27, 2016, 02:30:47 AM
That did it thanks again
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