A friend asked me to look at his NAD 3150. "Looks like a nice amplifier" sez I...

When I first turned it on, the "Protection" LED came on. This is with no signal, no speakers, volume all the way down. Blown output transistor, I'd say.

But I poked around a bit, found that when I probed around the protection circuitry, the LED went off. Diagnosis B, old capacitors.

So, to re-cap the main amplifier PCB on a NAD 3150, you need:

• 1 x 0.47u 50V
• 2 x 0.68u 25V
• 4 x 1u 25V
• 4 x 1u 50V
• 4 x 10u 50V
• 1 x 22u 50V
• 4 x 47u 10V
• 4 x 47u 25V
• 10 x 47u 50V
• 1 x 47u 63V
• 3 x 100u 10V
• 2 x 470u 63V
• 2 x 1000u 6.3V

I replaced them all with new 105C caps.