therealapalon

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My guess is you have a shorted output device and the loud buzz is the high ripple on the PSU caused by excessive loading. Disconnect the speaker & tweeter, power up the amp with a new fuse and measure across the outputs for the tweeter and main power amps.

If you have more than a few mV DC then this points to a short. If you have a variac then you can bring up the amp slowly and monitor the output for DC. If you don't already have one then a bulb limiter is a useful protection device while you're troubleshooting. Thank you for the reply. Upon closer inspection, the yellow wire off the HP plug is disconnected.

268 M1 Bin. It appears the lug somehow broke off. I tried to attach a jumper to see if this was the problem and my breaker popped. When I reset the breaker and left the yellow wire unattached the noise was there.

Take a few minutes to read through this manual before you power-up the Loudbox Performer. And thank for choosing the Fishman Loudbox Performer!

I ran it through a variac and at 10 volts it was making noise. I then took out the speakers and disconnected them all and put my meter on the wires for the tweeter. Avery Design Pro 5 Lite Edition.

I looked closer at the Power Supply board that is connected to the heatsink and there appears to be a small cap broken off with the trace from the board attached. I'll try and successfully post some photos. Where does the blue wire next to it go, perhaps to the tweeter? And if so is there a second wire on the tweeter? It looks like the male pin for the female on the yellow wire broke off of something, perhaps off the tweeter?

To assist my theory, do the red and black wires go to the woofer? I mean the red and black right with the blue and yellow, not the lone red and black to the left. This is just a thought, it might be something else of course.After looking closer at the small tweeter, the lug is definitely broken off of there. The red and black in question goto the woofer. Is it possible that I just had the bad luck of the lug breaking off of the tweeter and falling down near the mains and it made some intermittent contact? What about the caps that a broken off the trace? Should I replace them, or just try to reconnect them?

Maybe, but who knows. All you know is that if the connector didn't accidentally touch the mains you made sure that it did and you could have more damage than you began with. Disconnect the speaker and tweeter outputs and see if there's DC on either output. Which part of the circuit are the damaged caps located?True. Speakers are disconnected. The connector that has red/black/blue/yellow goes to the small tweeter and the small mid.

The connector that is away from the 4 wire connector that is a two wire connector that is Red/Black goes to the woofer. On the 4 wire connector, there was DC voltage present on Blue/Yellow even at very low voltage, but much less on Red/black and not so much at low voltage. On the 2 wire connector for the woofer there was DC voltage present even at low voltage. The unit was also drawing quite a few amps even at low voltage.

4amps before the 2a slow blow gave way. The damaged caps seems to be right near the r58 resistor and right below the vr2 trim pot.

You have three power amps that need to be checked. Plus your mains voltage could have appeared on the main PSU rails momentarily (by way of an output to supply short in U5) prior to the fuse blowing. You'll need to establish that all the DC voltages are correct and that you're not missing one of the supply rails and eliminate the possibility of excessive current draw in the PSU. The only way to do this is either to isolate the power supply or remove the excessive load so that the amp can power up. The tweeter amp chip is almost certainly blown and I'd carefully remove it to eliminate it.

Sometimes the supply pins read low resistance to the output pin and give a clearer indication of failure. Worthwhile just to take a measurement. The output devices on the other two amps need checking for shorts. You should also carefully inspect the board for any other visible damage. Fluke Linkware 6.2. Before embarking on any repair I would establish what's shorted/damaged.

Could be you have multiple faults. Sometimes it's necessary to remove the output transistors just to get to the point where an amp can be powered without blowing the fuse and then work from there. What's your mains voltage? You have three power amps that need to be checked. Plus your mains voltage could have appeared on the main PSU rails momentarily (by way of an output to supply short in U5) prior to the fuse blowing.