Fisher 800C Left channel Hum after resto

[ODYOFAEL]

Fisher 800C slight Hum/Buzz after resto

I just finished doing a resto for my 800c and used the Metalbone kit. I'll make it short. After the resto, I am getting a bit of hum/buzzz on both channels. And the hum is non-volume dependent.


What did I do wrong? :tears:
I need help badly. Thanks in advance.

 

[bhamham]

Since it's both channels I'd suspect the power supply. Have you restored the power supply? Changed out the can caps? After I've restored the power supply on my 400s it's eliminated all hum and they're as quiet as a church mouse even with headphones on.

 

[larryderouin]

There is ARMOR'ed cable inside, usually running along the side or a separator. Make sure it's soldered tight to the metal. It's an RF shield. I had a hum in a X-202 that turned out to be the Armor cable had come loose over the years and needed to be soldered back down. The Armor is there to cut down on RF interference in the signal path. Also moving leads to get to a cap or resistor and not putting them back where they were can cause the same thing. A wooden pick or LONG (12") match works well to move leads around with the unit powered up and on it's back. BE VERY CAREFUL! ONE HAND NEAR THE UNIT. The other in your back pocket, scratching itches.

Larry