Philco 46-420 Beitmans Riders - Printable Version
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RE: Philco 46-420 Beitmans Riders - Radioguy52 - 01-26-2022
It apears the tranformer next to the orange drop cap was added to complete the circuit when the PM was installed vs adding the resistors as in the original bullitin. Sorry if I have described it incorectly but it apeared to me this was to be acting as a choke to help smooth out the ac /dc rectifier circuit. I will give the resistor suggestion a try.
RE: Philco 46-420 Beitmans Riders - GarySP - 01-27-2022
In looking at the photo you posted I see several original caps in the radio. Were these restuffed? If not I would consider replacing them all. Old caps in the works could contribute to the hum issue. If they are original I would replace them all. Not that expensive to do and prudent to do on any rebuild. Old caps are a ticking timebomb. Just my two cents worth. Take care and BE HEALTHY! Gary
RE: Philco 46-420 Beitmans Riders - Radioguy52 - 01-27-2022
Gary: This forum is awesome for the expertise and knowledge shared.
Yes this was the "Before" Picture. I have replaced vs restuffed all of tyhe Caps. The two 30uf electrolytics shown were replaced with 32uf 160 vs caps. I published the photo because I may have been misinterpeting that small transformer. Choke? Coil? It apears it was added to the chasis when the EMSpeaker was removed to take the place of the original 500 ohm coil that was part of the speaker. I am going to try to scope the power out for ripple with the one in circuit, then replace it with a 500+- resistor and scope again plus hopefulyy hear less hum..
RE: Philco 46-420 Beitmans Riders - RodB - 01-27-2022
When a resistor replaces the field coil choke in a power supply filter you loose the filtering effect of the inductance. So to compensate you can increase the value of the filter caps. There's a limit to the amount of capacitance of the input capacitor which is found in the specs for the rectifier tube. Hope that fixes the hum.
RE: Philco 46-420 Beitmans Riders - Radioguy52 - 01-28-2022
Eureka: Pulled out that coil that measured 1 ohm in the filter circuit and replaced with a 500 ohm resister... Violla HUM is GONE!!
Thanks to this forum I learned a lot and now have a working HIPPO.. Excellet reception.