XR700 Power Mixer clips, low volume

[ChancesR]

Good Morning -
This mixer has the mains turned about midway, other settings are correct - and it's still going into compression with very low volume. I have the Drive schematic for this. I would like to know if I can safely remove the limiter IC's (478's - U2 on schematic) from both drive boards to test? *Naturally*, the owner is anxious to get this back as he has a gig TONIGHT. <<sigh>>

Thanks for the continued support! Warm regards,
ChancesR

[ChancesR]

Update: Just spoke with the owner. Seems the reverb was not fully functional prior to this clipping symptom. He had originally stated that it was just low volume, and going into compression. I have further diagnostics to do. Seriously doubt the 478's are the fault now.

The only schematic I could find on the XR700 was the drive board. Will also go in search on the PV site for a full set.

Regards,
C

[Enzo]

Peavey Parts will send you any schematic you request.

I doubt reverb will affect the power amps.

Yes, you can pop the 478s out of the boards and the amps will work fine - without the compressor function, of course.

What powr amp is in those, I forget?

[ChancesR]

Thanks, Enzo for your response. I'm not at the shop now, but IF my memory serves me, the power amp is a 400bh. I'll verify that tomorrow.

I'll also contact PV in the morning about that schematic. I had the presence of mind this afternoon to realize that the XR600b also used (in some) the same power amp as this mixer. I printed a copy before leaving - but haven't delved into it yet. Seemed like a good thing to drink coffee with -

I'll be taking voltages in the morning also to find out exactly where this is clipping. I'll post back tomorrow sometime with all of my 'findings'.

Great fixin's to you all...
Regards,
C

[ChancesR]

Fix: Xr700

Greetings to all,
Last post I said I'd reply 'next day'......does 2 months count?
I wanted to let everyone know that this is fixed - and what happened.

I went through ALL possibilities for this going into compression, and found no problems with any of the parts. I cleaned all of the jacks; cleaned all of the equilizer slides; replaced the reverb (he was also having problems with this). Set it up and tested for 4 hours without incident. My suspicion is that the gain (Main) wasn't properly set - but he's happy, I'm happy, and the world is better knowing that.

Good fixin's to everyone.....

Regards,
ChancesR