Need help repairing a turntable power supply

Thread Starter

THENOAMAN

Joined Jun 8, 2017
6
Hi,
I have a National Panasonic "Automatic recording level" with a turntable, tape player and radio. After I plugged it in, I have noticed that one of the capacitors on the main PCB burnt. So I have replaced it with a new one, but than I noticed that the power supply PCB has a burnt coil. It has no values on it or anything and I wanted to know if I can find this component or its values somewhere.
If more information is needed, please tell me.
Everything can be very helpful and will be amazing for me as I couldn't find anything about this model online.
Thank you.

IMG_20171204_164457_01.jpg IMG_20171204_173205_01.jpg
IMG-20171204-WA0027_01.jpg IMG_20171204_164457_01.jpg IMG_20171204_173205_01.jpg IMG-20171204-WA0027_01.jpg
 

wayneh

Joined Sep 9, 2010
17,153
I'd go ahead and replace the other electrolytic capacitors also. They can fail without any visible sign and are a frequent cause of death for old electronics. It's easier to just replace them than to test them fully, and then they'll be fresh for years to come.

I think that coil is a high (maybe RF) frequency choke but I don't have the chops to make a recommendation.
 

Thread Starter

THENOAMAN

Joined Jun 8, 2017
6
I'd go ahead and replace the other electrolytic capacitors also. They can fail without any visible sign and are a frequent cause of death for old electronics. It's easier to just replace them than to test them fully, and then they'll be fresh for years to come.

I think that coil is a high (maybe RF) frequency choke but I don't have the chops to make a recommendation.
Thanks for the reply,
Is there even a way to know what this coil was?
Anyway, thank you for the recommendation about the capacitors! I would test the condition of the whole system after I will replace the coil and see if it's worth replacing the capacitors.
 

Raymond Genovese

Joined Mar 5, 2016
1,658
Thanks for the reply,
Is there even a way to know what this coil was?
Anyway, thank you for the recommendation about the capacitors! I would test the condition of the whole system after I will replace the coil and see if it's worth replacing the capacitors.
A schematic or someone who has one that is not so crispy - but you already know that.

I know that you said that you could not find anything about this model online, but it might be worthwhile to post the model #, date you purchased it , etc..

Also, have you seen this site - you may want to post in that forum also - they have models from the 80's and later - you never know. But please post the outcome here if you get it working again.
 

philba

Joined Aug 17, 2017
960
If you can't find a schematic, you will need to trace the PCB. It's not hard but takes access to both sides of the PCB. I would look to see where the burnt coil connects. If the coil is in series with the output (ie one end of it only connects to the load), then it's value is not super critical. However, if it is part of a switch mode power supply then it's inductance value and current rating are critical.

Note that you need to be aware that the cause of the burnt coil may not be due to a bad cap (though it's a reasonable guess) and something else caused the failure.
 
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