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Akai AM-2450 Integrated Amplifier hi idle current.

Komet's picture

Anyone familiar with an Akai Am-2450 integrated amplifier? When Checking the idle current of the amp upon powering up the output meters pegged out and the idle current voltage went to over 200mv in both channels. There is no change when adjusting the potentiometers. This was with amp in Aux position with no input, volume control at zero, and speaker selector off. Normal voltage per service manual should be 20mv.
Now my following question could be applied to most amplifiers. What would be some issues that could cause this condition?
Any help would be appreciated!
Thank You,
Komet



Re: Akai AM-2450 Integrated Amplifier hi idle current.

If both channels are affected, this points to power supply, so check the capacitance multiplier (ripple filter) output voltages at TR4 and TR16. They should be positive 36.8 and negative 46.1 respectively, (plus or minus 10%). If either is incorrect, it will throw off the entire DC voltage distribution as this is a direct-coupled amplifier. A very likely culprit will be failed (dried out, weak, etc.) electrolytic capacitors, specifically any of C21, C22, C23, C25, C26 and C27. These measurements are based on both rails being correct. They are plus 44.5 and minus 44.5 volts.

Re: Akai AM-2450 Integrated Amplifier hi idle current.

Do you have 8 ohm loads on the outputs? I would check the main amplifier components like resistors for drift and bad capacitors.

Re: Akai AM-2450 Integrated Amplifier hi idle current.

Hi Komet,

I haven't taken a look at the schematic for this unit, but I can offer the following advice. Any time that there are identical problems in both channels of an amplifier you want to look at any part of the circuit that is common to both channels. It could be a resistor that feeds both channels or a regulated power supply that feeds both channels. Start there.

-bob