If it’s any consolation, the fix is literally changing one fiddy cent part and removing or reducing the value of one other one. This is all about making the output transformer and speaker play nice together. Mind blowing how little effort was expended to make sure those changes over the original AB763 version got vetted out before releasing it out in the wild.
If that amp was here, we could do a serious eval and refine what they were trying to do, but that’s probably not what you wanted to hear…
Dave
What’s even worse is that I just moved FROM Cali to NY! I’d be making the drive as we speak of I were still out there. Still, it gives me hope that someone out here might know what their doing if I explain this all to them, fingers crossed!
Eric
Hey, Dave,
Turns out my local shop is a Fender Authorized Service Center. Should I just ask them for the schematics if they have them or try and explain the issue based on what you’ve said here? Or, if you can help me find the words succinctly, I’d wholeheartedly appreciate it. If this is better done via e-mail so I’m not clogging up the forum, please let me know. Much appreciated!
Eric
We can hang out here a bit more on this since it may be useful for others.
But, it a nutshell…
This is going to require a modification to the power amp stage. However minor it is, an authorized warranty outlet is likely to advise that it’s not going to be a covered warranty repair if Fender hasn’t issued an ECO (Engineering Change Order) to address the issue. Based on my conversation with the person at Fender who is not involved in customer service or repair authorization, I have $100 bill that says they are not going to acknowledge that this is a design fault.
But I could be wrong, so it’s worth taking it in and letting them know what’s up. The good news is that you can demonstrate the problem without the Power Station connected, so they can’t say the cause is external.
Simply say something like this:
“I have it on pretty reliable authority that the negative feedback loop is causing parasitic oscillation above (whatever volume setting causes the noise in your clip) due to excess high frequency compensation. I understand that it may not be a covered repair, so I’d like an estimate to do a mod to correct it.” Then give them our support@fryette.com email address if they’d like to contact us for details.
I’d say there’s at best a 50/50 chance that they’ll reach out to us. I’m keeping expectations low so that if I underestimate the situation, you might be be pleasantly surprised.
Good luck!
Dave
Thank you so much. I’ll be bringing her in tomorrow morning and just dropped them an e-mail to give them a heads up. Very much appreciated, Dave. Hopefully we can get the ball rolling on this, fingers crossed!
Eric