HELP with Classic API VP26 problem

BluegrassDan · 27th May 2011

I built two Classic API VP26 pres and I'm having problems with one of them. It was working only intermittently and now not at all. All I get is a faint and distorted sound when I crank the gain all the way. Swapping op amps does not fix it. Phantom power works fine. Any thoughts?

dandeurloo · 27th May 2011

They are super simple builds so maybe re flow your solder connections. That might be all it is.

jsteiger · 27th May 2011

Since you have ruled out the opamp, do like Dan said. The biggest culprit I have seen is a bad or iffy solder joint on one of the 3 C&K pushbutton switches. There are a couple of PC pins that connect to the ground plane. They can be a tad more difficult to get a nice solder joint on.

Next step will be to inject a mic level signal in and probe along the circuit to see where it stops.

BluegrassDan · 27th May 2011

I've narrowed it down (I think) to the phase button. It cuts all signal when engaged. Any thoughts?

s.d.finley · 31st May 2011

Quote:

Originally Posted by BluegrassDan

I've narrowed it down (I think) to the phase button. It cuts all signal when engaged. Any thoughts?

Are you sure its the phase and not the mute? Which button is it?

BluegrassDan · 1st June 2011

I figured it out the other night. It was the mute button. I put a jumper between two of the posts and it works like a champ! The only drawback is that now the pre will not "mute" with the phase button engaged.

No big deal to me.

Thanks to Jeff for being Johnny-on-the-spot with email help. He deserves for me to buy more pre kits!!!

Big Tim · 15th January 2012

Bringing this thread back to life with a different problem - my VP26 passes signal fine, but the volume knobs and switches do not seem to make any difference in the sound. Where should I start my troubleshoot?

27th May 2011	#1
BluegrassDan Gear nut Joined: Nov 2007 Location: Elizabethton, TN Posts: 137 Thread Starter 2 Reviews written	HELP with Classic API VP26 problem I built two Classic API VP26 pres and I'm having problems with one of them. It was working only intermittently and now not at all. All I get is a faint and distorted sound when I crank the gain all the way. Swapping op amps does not fix it. Phantom power works fine. Any thoughts?

27th May 2011	#3
jsteiger Lives for gear Joined: Nov 2006 Location: Suburban Chicago Posts: 821	Since you have ruled out the opamp, do like Dan said. The biggest culprit I have seen is a bad or iffy solder joint on one of the 3 C&K pushbutton switches. There are a couple of PC pins that connect to the ground plane. They can be a tad more difficult to get a nice solder joint on. Next step will be to inject a mic level signal in and probe along the circuit to see where it stops. __________________ *Visit our Internet Store featuring EA replica API transformers, killer aluminum knobs and more...www.classicapi.com* GroupDIY 51x Racks

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27th May 2011	#2
dandeurloo Lives for gear Joined: Sep 2006 Location: Minneapolis Posts: 924	They are super simple builds so maybe re flow your solder connections. That might be all it is.

1st June 2011	#6
BluegrassDan Gear nut Joined: Nov 2007 Location: Elizabethton, TN Posts: 137 Thread Starter 2 Reviews written	I figured it out the other night. It was the mute button. I put a jumper between two of the posts and it works like a champ! The only drawback is that now the pre will not "mute" with the phase button engaged. No big deal to me. Thanks to Jeff for being Johnny-on-the-spot with email help. He deserves for me to buy more pre kits!!!

15th January 2012	#7
Big Tim Gear nut Joined: Feb 2009 Posts: 77	Bringing this thread back to life with a different problem - my VP26 passes signal fine, but the volume knobs and switches do not seem to make any difference in the sound. Where should I start my troubleshoot?