Reply To: Sentinel radio model 285P, hum problem

[Vince Cappuccitti]

Phil, thank you very much for responding to my post. I have not worked on the radio since posting due to not being sure how to proceed. What I didn’t mention is that the radio works very well with excellent reception on many stations and very good volume. Only the loudness of the hum is the problem.
The caps I replaced were not stuffed into the old cans but instead are in the underside of the chassis with the other components now. I left the cans in place and cut off the connections at their base. I did pay attention to the negative for the caps. I shifted the caps around within the chassis but it doesn’t seem to have any effect on the hum. Should I remove the cans and put the new caps on the topside of the chassis? could that help?
I didn’t check the tube filaments with a meter but did check them on a tube tester and even tried a couple new tubes with naive hope that would be the problem. Thanks for pointing out the possibility of burning out the filament with a 9v meter. would never have thought of that.
Are there caps in the IF cans? If there are I didn’t change those. Should they be? I will take a look at the schematic again.

I am using an isolation transformer and a dim bulb tester (not sure of the terminology)when I work on these old radios so reversing the plug didn’t help. I have tried turning off the flourescents as well with no change.

The justradios link is interesting with a lot of information to absorb and understand. I will take some time to dig into it.
I’ve checked some of the resistors but I’m not sure how far out of tolerance is acceptable. I did use a digital meter to do this. Could that have done something if the tubes were not removed.

The radio didn’t work at all when I got it, has taken a lot of effort to get it to this point and I would hate to give up on it when I’m so close.

Thanks again for responding Phil.