two Humming Gar2520 v4.1 DOA

[geardude]

You swapped output transistors,  if I see it correctly.

I didn't even see this post until you replied again, the short sentence seemed like a signature of the previous user. Sheesh.

Which are the output transistors? If this turns out to be the problem I'm surely gonna kick myself.

 

[moamps]

Q7 and Q8
BD139 and 140

 

[JohnRoberts]

+1 the voltages on Q8/7 look even worse than the others.

JR

 

[Whoops]

Are you sure BD139 and 140 are not swapped?

when I had problems with building these Opamps, not having continuity between top and bottom pcb at some places, those 2 transistors kept being shot by the fault.

I had to fix first the issue and then replace them for new ones.

Can you replace those? they re not expensive

 

[geardude]

I'm about to swap them this appears to be the issue....wow. Be back shortly

 

[Whoops]

I'm about to swap them this appears to be the issue....wow. Be back shortly

From the picture you sent I think I can see that in the Q8 place you put a BD139 so in Q7 you probably used a BD140, it should be the other way around.

 

[geardude]

this was indeed the problem. wow. chalk it up to don't solder late even when you're close to finishing.

Thanks guys.

Unfortunately I lost one copper bad in the desoldering process of one gar so I guess its donezo. Better two lose one then two I suppose unless there's a fix for that too.

Thanks again guys, wish I would seen this day one!!!

 

[Whoops]

this was indeed the problem. wow. chalk it up to don't solder late even when you're close to finishing.

Thanks guys.

Unfortunately I lost one copper bad in the desoldering process of one gar so I guess its donezo. Better two lose one then two I suppose unless there's a fix for that too.

Thanks again guys, wish I would seen this day one!!!

Yes the traces dont take a lot of heat while desoldering, but its totally fixable. Use a small wire or resistor leg to jump the broken trace, check continuity after and you should be fine!