Nakamichi CA-5 Stereo Pre and major hum - diyAudio
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Old 22nd January 2011, 03:53 AM   #1
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Default Nakamichi CA-5 Stereo Pre and major hum

Hey guys, first post here....

I just received my Nakamichi CA-5. I ordered it form Ebay for an OK price...according to the seller it is pristine condition and works, zero functionality problems. Well...it does look nice, however once hooking it up, I ran in to major issues with the audio.

First off, when turning the output level knob, I got static on every turn. The static would only occur when the knob was turned.

2nd...after leaving it turned on for a bit it suddenly began to hum. Then it got louder and louder and the hum seem to be amplifying itself. That's what it seemed at least.

Now when turning it on, I get nothing but hum. I get no audio...just hum. The output volume knob is turned all the way down and still I get hum, and still the hum gets louder and louder on its own.

I've tried both of the units 2 different outputs, I've tried all of the inputs and nothing. Still hum. The hum does not go away, it just stays there and gets worse and worse.

I had it hooked up to an Emotiva XPA-3 amplifier. The amp was powering 2 JBL tower speakers. This setup was just for testing purposes. Lucky for me, nothing blew...it got very very loud. I don't think I've ever seen my speakers flex like that before.

Any insight on where to start looking for such a problem? What could it be??

Suffice to say, I am disappointed.
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Old 22nd January 2011, 05:18 AM   #2
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Didn't see an edit button..

anyways, made some progress.

I turned the unit on...then cranked the output level knob all the way to max...yes there was major hum...but it wasn't getting louder anymore. Something knew...no sure why. I could barely hear music coming through the speakers. That was a first. So I continued to crank the output level knob all the way to max....it got super crackly and distorted. Mind you the music had gotten louder but was very thin and sounded as if it was behind a wall of hum. I was about to give up....put the knob back to Zero and turned the unit off.

Turned it back on....and magically I heard no hum...then I turned the knob...no static sound. Then I played some music, and it came to life. No noise...music was super clean and beautiful.

I don't get it.....but the problem seems to be coming from the unit's output volume knob.

maybe it needs to be cleaned or....something? Kind of beyond me.

What does an output level knob have anything to do with hum? and what does cranking it all the way to max have anything to do with me having fixed it now...or at least improved it? I still have to find out why its like this.
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