Fender Cyber Twin-No master volume

[badaxxe]

I have 3 Cybertwins, 2 work fine and  one that powers up and all the knobs move and are active but the master volume. There is a slight pop when turned on but nothing from the input. There is a signal from "send" the output MOSFETs are heating and some times the amp will go to ten, then lots of sound. Replaced tubes, checked for ribbon connections, reformatted CMOS, Any ideas?

[Enzo]

Hi, your terminology is confusing me.  If I get you, there is no output from the speakers, right?

"The output MOSFETs are heating..."   Um, this amp has no MOSFETs, do you mean output transistors?  And by heating do you mean overheating?

If the amp likes to be quiet, check the headphones jack.  There is a contact in that jack that mutes the amp.  if it gets dirty, it can mute when you don;t want it to.   Also, try plugginf into the two FX returns with a guitar.  Does that come out strong?

[badaxxe]

Hello Enzo,
Correct no output from speakers. No output from phones or XLR. No mster volume readout on LCD when mater volume pot is moved. tried FX returns- zero. Sorry about MOSFET as I am used to the old style transistors PNP, NPN TP3 . Any ideas? Thanks

[Enzo]

Then start at the start, are all power supplies present, up to voltage, and clean?

Get the schematic set from Fender.

[badaxxe]

How many power supplies are there and which one runs the output stage? Someone on another forum said Enzo knows his stuff on Cyber Twins. Have you ever had the problem that I am experiencing? Is there a specific area that I should be looking at?

[Enzo]

Get ahold of Fender for the schematics, it may even be on their web site.  Certainly way too large a file for me to post.

Without looking it up, solid state power amp needs positive and negative voltage supplies of some 40v or thereabouts.  I don;t care if it is 40, 45, 50, 35.  I just don;t want it to be absent.  And the op amps and low voltage stuff will be using +/-15VDC supplies.  Digital circuits will be using +5VDC.  I don't know offhand if there are relay supplies or if the couple tubes have heater supplies.  SO that looks like at least 5 supplies to check.

[badaxxe]

Trying to find my Cyber Twin Schematics. I will post when I figure out the PS voltages.

[Enzo]

If the schematics are not posted in the schematic collection on the Fender web site, CONTACT them and request them.   There is a note right there about schematics not in the listing.