[Lifthanger]

Hi

just finished building and learned how to desolder finally.
Now the initial check. I get a quiescent current of 43mA the battery is at 9.4V
and its a high performance model.
This should be too much?!

Thanks.

edit: with an empty 7V it is around 25mA but thats not surprising

 

[amb]

43mA is high than expected. I also do not expect the current to change that much between 7V and 9.4V.

What are the output DC offset measurements?

 

[Lifthanger]

yeah that's it.

5mV and 4.5V! between ig and ol. ouch

 

[sergery]

Having nearly the same issue. sound went bad suddenly, went through checks to find rail splitter was bad. replaced that but noticed a spark when I was testing a second time - now the dc offset is the same as Lifthanger's. This is one of the opamps as other connections look good for me, but which? prefer not to replace both

is there a test to determine if the opamps are good, other than those listed in "initial check"?

thanks

 

[Lifthanger]

the ground opamp should be single. thus if only one channel has high offset it should be the dualopamp... or something else

 

[Lifthanger]

just found out: the input pins of the left OPamp (5,6) both are at about 2.5V to Iground.
Though not the same value on both.

is this the power supply leaking through the dead opamp?

 

[amb]

Cold solder joint at the input pins?

 

[Lifthanger]

the joints were fine, but I reflew everything. it I turn the pot a bit 5-IG goes up to 3.5V and 6-ig to 2.75 volts. It seems as if the opamp at least wants to do his job. don't know how to find out where the voltage comes from.
I'll try to trace it back as good as I can.

 

[amb]

Probably a blown U5.

 

[Lifthanger]

thanks for your time amb

edit: confirmed. after taking out U5 the voltage on pins 5 and 6 are gone. getting in the new one will be a royal pain though

.

 

[Lifthanger]

just wanted to confirm this. All is well with the new ADsomething. I guess I killed the old one with heat. But I got new leaded solder now.

Love it with the gamma1 and my HD595s. Gotta do some testing with the opus and my CKK3s

Thanks AMB.