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DC bias problem
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DC bias problem

by xtals on Tue Aug 08, 2017 1:54 pm

Hi! :)

I've started to build my xox (from Zwillyx shop).
Following the manual at page 37 i'm supposed to test DC bias and have 8.5VDC, but when i put the multimeter probes i read a 0v value.
All other voltages are fine according the manual.

What you suggest to check?

Thanks!

xtals
 
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Re: DC bias problem

by antto on Tue Aug 08, 2017 5:26 pm

you've probably received some printed build manual, but in the past most folks have used the online build manual, which is not paged like a book
so can you clarify exactly at what point of the build process you are that instructs you to measure that voltage?

antto
 
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Re: DC bias problem

by xtals on Tue Aug 08, 2017 5:37 pm

Hi!

I'm using this manual:

http://www.ladyada.net/make/x0xb0x/fab/vco.html

I think that's the same from the Willzyx site after all!

xtals
 
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Re: DC bias problem

by antto on Tue Aug 08, 2017 5:42 pm

most probably it's the same manual, printed on paper
but my question was: what is on page 37?

antto
 
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Re: DC bias problem

by xtals on Tue Aug 08, 2017 5:59 pm

This:

Image

And that's the description:

"If you don't have a scope, you should at least measure the DC bias, which is about 8.5VDC"

Then, measuring with multimeter at the resistor i have 0V!

thanks

xtals
 
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Joined: Tue Aug 08, 2017 1:46 pm

Re: DC bias problem

by xtals on Wed Aug 09, 2017 3:21 pm

Update:

I have solved the problem: Q26 (2SC1583) had some really bad soldering on it...on the smd part a lot of solder paste was left unsoldered and then some pins was shorted.
Cleaned it with ultrasonic bath first and then resoldered, DC bias is perfect now!

Thanks again!

xtals
 
Posts: 4
Joined: Tue Aug 08, 2017 1:46 pm

Please be positive and constructive with your questions and comments.