HI My Rowland Kc60 suddenly has no power. I presume it is shorted out...can I replace the fuse myself, and if so - where and what fuse do I buy and how do I access it on the amp?

Old age has finally caught up with both myself and your vintage Peavey. Things like shorted diodes and transistors sometimes do not physically give themselves away, Also, many times it takes a trained eye to discern the components that have failed in a more discrete manner. It's either repair shop or replacement time which I recommend the latter.

Hi,

Looks like the power module went out, could be either LM3886T Power IC or Mosfet Module But certainly is in the output stage where your problem is, hope this helps to troubleshoot the issue at least...

Transformers RARELY fail. It is likely that either one side of the amplifier has shorted or there is a failure in the rectifier/filter circuit of the power supply. Take it for repair unless you are adept at electronic repair. Do NOT continue to replace the fuse as you MAY cause futher damage. Use a 25 or 40 watt lamp in series with your power cord to limit current while troubleshooting.

Hi,
Looks like the main power IC is shorted!
Check the main power amp IC and replace it if there is a short between their pins!

Hope that helps you out!

Hi pcruzx,
Sometimes replacing the fuse alone with exact voltage and ampere ratings will cure the problem(you're lucky) but not all. Sometimes further damaged gone to other parts most especially the voltage regulator transistor/IC (mounted in heat sink) and the opened the fusible resistor in line with the supply(B+).
First check the fuse, for sure it was already blown. If you've replaced the fuse and immediately blew again after powering on the unit, this was an indication of shorted parts near the AC line. Click this LINK for more info.
Hope I helped you.
Have a nice day!
Thanks for using Fixya.

This MIGHT be close to your unit... it is for the KC-100... they often use the same circuitry.

http://elektrotanya.com/roland_kc-100.pdf/download.html

Scroll down to the "Get Manual" and click on it to download. There may be slight variations but these amps are simple enough to troubleshoot. USE the old trick of putting an incandescent lamp of say 100 watts in series with the power input to act as resetable fuse and save fuses when powering up after a repair.

This is likely a pwer supply problem... BUT do check that the power cord is properly seated... pretty common that these work loose.

Does the hum exist with no cable plugged in? If so, take in for service. If there is no hum with cable out, then try new cable and/or musical instrument be it guitar or keyboard as the problem is likely in those.

It probably is shorted filter capacitor(s) or shorted rectifier(s).

A shorted output tube could do this, but those are unlikely unless unit has been dropped.

Worst case is shorted power transformer.

In any case do NOT replace the fuses and keep trying as further damage could result. Take unit in for repair if you are not skilled in electronics... there are high voltages in this unit that are lethal.

Look for a failure in the power supply section. You will need electronic experience or someone who has that.

If the fuse is glass and blows silvery inside thia means a direct short inside. SUSPECT the input rectifier or filter capacitor(s).

Do testing with a 100 watt light bulb in series with the hot side of the power cord to avoid blowing fuses.