Yamaha KX393 tape deck play back crackling noise - UK Vintage Radio Repair and Restoration Discussion Forum

simon72post · 2nd Oct 2021, 5:51 pm

Hello

Please could someone give me a little guidance.
I have a yamaha KX393 tape deck which has all ways worked fine.

But it has suddenly got a problem on play back. I get crackling noises its mainly on the right channel but also a little on the left. And the meter on the right hand channel sometimes randomly shots to the top and I get louder clicks and crackling.

I am quite happy trying to fix things and work with electronics but never repaired an amplifier circuit.

I have had a look at the circuit diagram and the yamaha has 2 output IC's in the playback amp the first a LA3161 then a NJM4558L.
After the playback amp the signals then go through the dolby circuits before the output sockets.

Would you say the two amplifier IC's is the best place to start or do you think it might be something else more like a capacitor.

Any tips on the best way to track the problem down would be appreciated.

Thanks

paulsherwin · 2nd Oct 2021, 6:01 pm

This is pretty unlikely to be a chip fault. Start with the basics - clean all the switch contacts, and then examine the boards carefully for dry joints. After that, check all the voltage rails, ideally with a scope.

simon72post · 3rd Oct 2021, 10:49 am

Thank you

knobtwiddler · 5th Oct 2021, 1:13 pm

Do you have a soundcard? There is a piece of SW that you can download for free: audiotester.de

You will see that a lot of tape fanatics use it. It has a live-view FFT analyser. This could potentially prove useful in working out where your problem lies. You can look at the frequency distribution and content. Can be very useful in determining where a fault lies!

2nd Oct 2021, 5:51 pm	#1
simon72post Diode Join Date: Oct 2021 Location: Wimborne, Dorset, UK. Posts: 7	Yamaha KX393 tape deck play back crackling noise Hello Please could someone give me a little guidance. I have a yamaha KX393 tape deck which has all ways worked fine. But it has suddenly got a problem on play back. I get crackling noises its mainly on the right channel but also a little on the left. And the meter on the right hand channel sometimes randomly shots to the top and I get louder clicks and crackling. I am quite happy trying to fix things and work with electronics but never repaired an amplifier circuit. I have had a look at the circuit diagram and the yamaha has 2 output IC's in the playback amp the first a LA3161 then a NJM4558L. After the playback amp the signals then go through the dolby circuits before the output sockets. Would you say the two amplifier IC's is the best place to start or do you think it might be something else more like a capacitor. Any tips on the best way to track the problem down would be appreciated. Thanks

2nd Oct 2021, 6:01 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: Yamaha KX393 tape deck play back crackling noise This is pretty unlikely to be a chip fault. Start with the basics - clean all the switch contacts, and then examine the boards carefully for dry joints. After that, check all the voltage rails, ideally with a scope.

3rd Oct 2021, 10:49 am	#3
simon72post Diode Join Date: Oct 2021 Location: Wimborne, Dorset, UK. Posts: 7	Re: Yamaha KX393 tape deck play back crackling noise Thank you

5th Oct 2021, 1:13 pm	#4
knobtwiddler Octode Join Date: Mar 2016 Location: London, UK. Posts: 1,051	Re: Yamaha KX393 tape deck play back crackling noise Do you have a soundcard? There is a piece of SW that you can download for free: audiotester.de You will see that a lot of tape fanatics use it. It has a live-view FFT analyser. This could potentially prove useful in working out where your problem lies. You can look at the frequency distribution and content. Can be very useful in determining where a fault lies!