OLD THREAD DAC End by Andrea Ciuffoli - Page 93

Salas · 26th February 2010, 10:25 PM

Can you say there is no difference or error after looking at its bro +5V both form above and underneath on same board?

adamus · 26th February 2010, 10:28 PM

no difference at all. I even braved the wife's eyes. They look identical. no bad traces, checked witha jultimeter.

Salas · 26th February 2010, 10:34 PM

Lets do something? Can you short R15 or parallel a 10-33R on its legs?

adamus · 26th February 2010, 10:41 PM

done.

no change

Salas · 26th February 2010, 10:43 PM

That's weird. If everything is exactly as in the one next door and it does not behave I am out of more wits than changing the odd shot electrolytic.

adamus · 26th February 2010, 10:46 PM

thats what i am going to try next. I'll sleep on it and have a go tomorrow.

Voltage over Q18 on the good board is 500-600 mv

Its less than half that on the 'bad board' but the idss is bigger

Salas · 26th February 2010, 10:54 PM

R17 could eat mV if it is 100R instead 10R by mistake. Checked that also?

adamus · 11:01 PM

yes, i have checked all the compenents visually and with a multimeter where possible.

Q18 will be my target tomorrow, but i can easily adjust vref to 4.8v+ so i have my doubts it will do anything. it all goes dodgey round q15.....

adamus · 27th February 2010, 09:38 AM

so, i tested the voltage with the 5v analogue line into the digital.... and guess what - it sits at exactly the same voltage.

All that faffing at it has to eb something on the dac board!

Salas · 27th February 2010, 09:53 AM

Don't know what happens next, but the main reg should work ok without being connected. Does it?

26th February 2010, 10:59 PM	#928
adamus diyAudio Member Join Date: Apr 2008	yes, i have checked all the compenents visually and with a multimeter where possible. Q18 will be my target tomorrow, but i can easily adjust vref to 4.8v+ so i have my doubts it will do anything. it all goes dodgey round q15..... Last edited by adamus; 26th February 2010 at 11:01 PM.

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26th February 2010, 10:25 PM	#921
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Can you say there is no difference or error after looking at its bro +5V both form above and underneath on same board?

26th February 2010, 10:28 PM	#922
adamus diyAudio Member Join Date: Apr 2008	no difference at all. I even braved the wife's eyes. They look identical. no bad traces, checked witha jultimeter.

26th February 2010, 10:34 PM	#923
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Lets do something? Can you short R15 or parallel a 10-33R on its legs?

26th February 2010, 10:41 PM	#924
adamus diyAudio Member Join Date: Apr 2008	done. no change

26th February 2010, 10:43 PM	#925
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	That's weird. If everything is exactly as in the one next door and it does not behave I am out of more wits than changing the odd shot electrolytic.

26th February 2010, 10:46 PM	#926
adamus diyAudio Member Join Date: Apr 2008	thats what i am going to try next. I'll sleep on it and have a go tomorrow. Voltage over Q18 on the good board is 500-600 mv Its less than half that on the 'bad board' but the idss is bigger

26th February 2010, 10:54 PM	#927
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	R17 could eat mV if it is 100R instead 10R by mistake. Checked that also?

27th February 2010, 09:38 AM	#929
adamus diyAudio Member Join Date: Apr 2008	so, i tested the voltage with the 5v analogue line into the digital.... and guess what - it sits at exactly the same voltage. All that faffing at it has to eb something on the dac board!

27th February 2010, 09:53 AM	#930
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Don't know what happens next, but the main reg should work ok without being connected. Does it?