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x0xb0x no sound except clicking noise
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x0xb0x no sound except clicking noise

by tanta on Sun May 19, 2013 2:54 pm

I've builded a x0xb0x and all I can hear is clicking noise in all mode. I have search relate topics in this forum. Most likely it is the VCO problem. I've done some testing in the VCO part.
1./ I get 5.33V and 11.9V on J4, so the power is ok.
2./ I have checked all caps and resistor value is correct in the VCO part.
3./ I have re-touch every joint with the soldering iron make sure they have good contact.
4./ I have check some DC votage , I get DC 2V and 3V on IC11 pin 7 when I press the middle C and C1 ( I guess this is correct?)
5./ I have check the DC voltage around the VCO area, I don't have correct reading around D25 (junction point on D25 and Q27, junction point of D25 and Q24 Q25). Correct value should be something around 5.7v to 5.88V, but I have 0V on both junction point.
6./ I have replace all D25 , Q27 Q24 Q25 2SC1583, 74HC174 and 4066 with new parts, the problem is still there.
I have no idea what is causing the problem. Please help. Thanks
tanta
 
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Re: x0xb0x no sound except clicking noise

by MMM on Sun May 19, 2013 3:42 pm

Check if those two junction points have possibly an (unwanted) short to ground. Just measure if there is continuity between them to ground.
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Re: x0xb0x no sound except clicking noise

by tanta on Mon May 20, 2013 12:34 am

No, they are not short to ground. Is there any particular point I should check the DC voltage?
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Re: x0xb0x no sound except clicking noise

by MMM on Mon May 20, 2013 4:11 am

I'm not home right now and hence can't make any comparisons (so this would have to wait a few days); however you might want to remove Q25 to see if there is any change around D25.
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Re: x0xb0x no sound except clicking noise

by x-11 on Thu May 23, 2013 4:08 am

Hi Tanta,

is q22 a 2sc2291
and q21,q12,q26 are 2sc1583
maybe you swapped one accidentialy.
this causes clicking sound and no waveform.

u get saw on headphone test?(see building guide)

greetS
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Re: x0xb0x no sound except clicking noise

by shawnsick on Thu Mar 13, 2014 3:31 pm

Did this problem ever get solved?
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Re: x0xb0x no sound except clicking noise

by DrHouse on Sat Dec 30, 2017 1:54 pm

This exact same problem with xoxshop kit is driving me crazy, 0v on D25, Q27 junction. Other voltages seems to be quite ok, DC Bias however is 10v and it should be around 8.5v according to build manual, I am using 2x 1.5volt batteries to give me around 3.2v cv.
I have so far only done power, which is ok 11.78v and 5.33v and soldered only VCO parts. Can't heard anything, not even clicking with pair of Sennheiser PX100 (impedance 32 ohm).
I also changed Q27, Q24, Q25 and D25, no change and there seems to be no shorts.
I do not have scope, only multimeter, any suggestion what to check next?

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Re: x0xb0x no sound except clicking noise

by DrHouse on Sun Dec 31, 2017 7:02 am

And it works!
I didn't have 2SC1583 but PMP4201 based replacement part and another of it transistors was dead, or SMD part is not correctly soldered (have to check that still).
So if it does not work, it is always fake 2SC1583 or faulty replacement part :P

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