My Kb3 sn512236482004306 is completely dead. Input fuse is good, voltage to power supply is good. Any suggestions where I might go from here?

STart at the start. Did you actually measure the mains fuse with a meter? They can look OK and still be bad.

But failing that bit of luck, the 120v from the wall needs to get to the power transformer inside. (Or 240v in other parts of the world) So we could have:
bad power cord, bad power switch, bad fuse holder, bad wiring between all these things, and finally, and by far least likely, a bad power transformer.

Here is a trick. Turn the amp power switch to ON, but do not plug the cord into the wall outlet. Set your meter to resistance, and measure resistance between the two main prongs on your power plug. If you get some low figure like 50-200 ohms (just guessing), then the mains circuits are probably OK. If you get an open - same reading as not touching your probes to anything - then the mains circuits are amiss.

Now all that may be OK, but the low voltage inside is out, so none of the lights will come on and the preamp will be dead. SO we look inside for more fuses, check the wires from the power transformer to the main board for AC voltage in the right range, and see if there is indeed +/-15VDC in the system.

And as someone who services this stuff for a living, I can tell you that a "dead" amp is usually a simpler thing to fix that poor performance. In my shop You would probably be looking at $60-75 labor plus parts. Check with your local shops for their rates.

Thanks, all your suggestions were followed through with. Input voltage is OK but from there? I have no schematic to follow so I'm kind of lost. Please give me your address and shop name so maybe I can send this Kb3 to you?

You can get any Peavey schematics for the asking from customer service at the factory. Have your serial number handy in case there is more than one version, and call them.

I would be happy to do this work for you, but shipping amps is not cheap. I am in Lansing, Michigan. Peavey has a network of many authorized repair shops around the country, and there is probably one near you. This is the sort of problem that any competent repair shop can handle easily.

On the other hand, I am not in the business to turn people away. SO feel free to call me, I am in the shop M-F AFTER 6:30PM. (We work musician hours here)

Shiawassee Technical
5223 South ML King Blvd
Lansing, MI 48911
Ph 517-882-2544