03-27-2020, 06:39 PM
I'm just finishing up on my Model 66 chassis. Full electronic repair, all caps, out of spec resistors, alignment etc.
What I've noticed is a noticeable 120hz hum coming from the speaker.Of course the electrolytics were replaced with exact OE values, and I've checked them to be sure they are not faulty.
I've discovered that I can just about eliminate the hum by changing the value of the 8uf cap connected in the screen circuit to 30uf or so.
I could just do that (change the capacitance value that is) but I'm wondering why the hum is occurring with the correct value?
Any help or suggestions would be appreciated.
Thanks,
Al
What I've noticed is a noticeable 120hz hum coming from the speaker.Of course the electrolytics were replaced with exact OE values, and I've checked them to be sure they are not faulty.
I've discovered that I can just about eliminate the hum by changing the value of the 8uf cap connected in the screen circuit to 30uf or so.
I could just do that (change the capacitance value that is) but I'm wondering why the hum is occurring with the correct value?
Any help or suggestions would be appreciated.
Thanks,
Al
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
