[bjarnetv]

i finished up my mini3, and the initial sanity check went fine, but when i tried the Quiescent current check, the power light went on even though the volume pot was turned off, measuring around 42,0.
after turning it on, the light intensity increased, and it measures 74,3.
i cant find any solder joints, and visually everything looks ok.

so... what do i do next, to determine the problem?

 

[bjarnetv]

bump. couldnt find any answers by searching old threads.

 

[amb]

Are those measurement numbers in mA?
Check to make sure the 7812 regulator's mounting screw isn't shorting to the board's ground plane.

 

[bjarnetv]

you were right! thanks a lot, guess i tightened the screw to much.

time to do the rest of the checks, and see if everything survived

 

[bjarnetv]

so i finished it up, and everything seemed fine, but after powering it up and playing for a few minutes, i get some crackling/static noise in the left channel.
anyone have any idea what the issue might be?

 

[pdupiano]

try reflowing the solder to stuff you might have an intermittent connection

 

[bjarnetv]

reflowed all the solders, but as the issue persisted i decided to do the dc offset check once more.
the left channel started out at around 5mv (G=0mv, R=2mv) but after a while it started fluctuating between 5 and 300mv.
i guess this means the U5 needs replacing?

 

[bjarnetv]

bah! forget everything i said in the earlier post. i redid the left channel solders on the u5 opamp one last time, and now the dc is stable at 2mv on both channels

great sounding amp, and it drives the fostex T30 surprisingly well.
i suspect an ortho/mini3 combo would be hard to beat for the money

 

[bjarnetv]

NOOOOoooo!!! worst day ever!
when i turned on my mini3 today, the static crackling sound was back, so i decided to try and reflow all the solder joints again, only one problem... my soldering iron no longer worked!
What! is there an indian burial ground underneath my apartment? they both worked perfectly yesterday!

 

[Kabeer]

hope you get it fixed. Mini3 rocks (even with my orthos) (ps thanks for the great amp design amb).

 

[bjarnetv]

i found an old, extremely crappy soldering iron, and managed to reflow u4 and u5 yet again, and its back to normal.
hope it stays operational this time -_-;