Post mortem of an ESI nEar 05 studio monitor with pictures

[rmb]

Stube40: Check the bridge rectifier(s) - without knowing anything about this amp, the plus and minus supplies may have separate rectifiers. Radio Shack has bridge rectifiers in the $4 range that should work. The 20 VAC on the neg supply rail doesn't sound good....better check the electrolytics after replacing the rectifier because those may also be bad.

Live near a radio or TV station? Depending on how close you are to the transmitting antenna, unshielded speaker leads can pick up the signal and the semiconductors in the amplifier may demodulate it, causing audible noise or buzz. The amplifier's manufacturer may be able to suggest fixes to radio-frequency interference...or you may want to try bypassing the speaker terminals (at the amplifier) with 0.01 uF 400 volt mylar or ceramic capacitors of good quality. (Use no junk components here, a short will wipe out the output section!)

 

[Ian Finch]

see posts #12 & #18.

 

[jaycee]

If you can figure out some alternate way of mounting those capacitors close by, you can always connect them to the main PCB with some wire, similar in gauge to the wires coming from the mains transformer.

I'd personally replace that 4A bridge rectifier with at least an 8A one.

 

[JMFahey]

Have you checked the internal fuses?

 

[jaycee]

As indicated in posts #12 and #18, he found the problem - crappy Acon capacitors gone bad