cyber twin no sound

[Enzo]

I don't know if it is the DAC itself or not, all we know at this point is that the problem is in the digital section. The DAC is merely the gateway between digital and analog. Could be the DAC, could be something behind it.

It is a DAC/ADC, but they refer to it as a CODEC (coder/decoder) It is not proprietary, it is an industry part. Fender gives it a part number, but that is no guarantee they stock it anywhere but where the boards are made.

Fender 0056861005 AK4528 CODEC $26.65

At this point a host board swap sounds attractive.

[Steve Conner]

The host board is probably the most expensive and hardest to get part in the whole amp, so by Murphy's law, it probably is what went bad. The AK4528 is indeed an industry standard codec, I have a few pieces of digital gear that use it as well as other chips in the same family.

Anyway...

Does the digital display light and display what it's supposed to, and do the digital controls work for changing patches and such like? (the large encoder knob etc) Do the motorized knobs spin when you change patches? If so, the DSP is probably good, and all the digital stuff is probably getting power. Therefore, the problem is either in the codec chips, or the power supplies to them, or in the analog part of the host board. (Maybe a shorted out op-amp, which would explain the original fuse blowing. The analog parts of the codec chips never run directly off the +/- 15V, so a bad codec would not blow a fuse.)

If the above digital stuff doesn't work at all, or seems cranky or corrupted, you should suspect the DSP or other digital component. The most likely cause is a bad logic power supply, that either is not giving enough voltage to run everything reliably, or gave too much when you were messing with the fuses, causing one of the fancy many-legged chips to blow out. (Murphy's law says it blew the one with the most and smallest pins, or even a ball grid array package.)

If you have a scope and X10 probe, you can check to see if any quartz crystals you find on the host board are oscillating at the right frequencies. That's one of the first things I do when debugging stuff with microprocessors in it. The X10 is mandatory, the piece of coax with alligator clips on the end that many newbies use with their scope has a lot of capacitance, and can load the crystal down and stop it.

[methodofcontrol]

i don't own a scope. so digital trouble shooting might be an issue.
if replacing the whole host board will definately fix the issue, i feel that so long as i could get one....i'd be best off doing it that way.
all of the digital display stuff seems to work just fine. the motorized knobs do change w/ different settings.
i need a fender dealer to get me the host board...is that correct? any suggestions there? what's my best bet to score one of those?

[Enzo]

You might try contacting Fender to ask just what part number to ask for so your dealer can order it and to find out if they are indeed still available, and what MSRP is on them. ANy Fender dealer who is willing to order parts for you can order the part, assuming availability. It is vetter if you do the research so they don't misinterpret what you want and order the little display board or something. Fender may require the dud back for example. In warranty service, the little digital board swaps are the only parts they ever want back. Although I do have a dead host board here.