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Akai AA-1030L - overloaded phono input now it distorts

Almiscarado

Almiscarado

Member
Hi everyone!

I got a classic Akai AA-1030L that was working fine, until I decided to connect the RCA outputs of a AT Sound Burger to it's Phono inputs.
It obviously overloaded the phono inputs, so I disconnected the cables and connected it to the AUX line in. It was still distorted! I connected the FM radio, and the distortion was there.

So... is this bad luck / coincidence, or did I burn something up when I overloaded the phono input? What components should I try to look for? I really liked this amplifier, would really like to repair it...

Any help will be very usefull!

Sergio
 
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You could have a damaged transistor somewhere. I had a similar symptom in Akai AA-810, a not-quite-dead-but-damaged transistor was causing it. Could be something else though. If the distortion is present regardless of the source, the only thing we can assume is that the problem is either in the signal path after the source selector (so not in the phono stage), or its a power supply problem. Try with headphones. If sound through headphones is not distorted, it's probably not in the preamp. Also, test your speakers, it could be a speaker problem too. Is distortion present in both channels or one channel? If it's only one channel, switch speakers between channels, see if distortion follow the speaker or stays in the channel.
 
here is the service manual:
http://www.hifiengine.com/manual_library/akai/aa-1030.shtml

I see there are 2 transistors after the phono preamp, one after the volume control, before the tone controls, one after those tone controls.

It could be you overloaded the preamp, and damaged some transistor, or perhaps one regulator in the power supply went bad. There are 2 voltage regulators feeding the preamp and other circuits (TR1 , TR2 and TR3 on the power supply board). If some of those went bad, you'll have unequal voltages and distorted sound.

Isolating or narrowing the problem doing some more testing will help to diagnose.

You need to measure voltages inside the amplifier to fix it. Can you do that safely?
 
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