Phonoland

Transformers don't usually cause that kind of problem. More likely it is your electolytic capacitors gone bad. This is actually good because capacitors cost $ and transformers cost $$$$$$$$. Bad capacitors will cause hum and eventually lunch your amp.

marcapra wrote:I just got my 1926 Brunswick Panatrope [b]back from the shop. It is a phonograph only model P-9 with a chassis that was made by RCA and looks like a RCA Model 104 speaker, sometimes called a Tomcat. It works now, but has a loud 60 cycle hum. I guess it could be a bad transformer? any ideas of how to fix it? Marc.[/b]

A repair shop?
Sounds like a bad ground connection, perhaps.

I don't give the customer back anything from my shop, unless it's working to the best of its ability.

Come to think of it, my repair man did say to try to ground the chassis with a spare wire. I'll try that. He did say that he only replaces capacitors that are bad instead of replacing all of them. Also he did say that a previous repairman had rewired the chassis moving the tube wiring to left in order to put a different tube in. Don't know why he did that. These Tomcats are very primitive amplifiers!

I just grounded the chassis which got rid of most of the 60 cycle hum! Sounds like Matt knows what he's talking about! I didn't know where I could get to the chassis, since it is covered by a primitive metal shroud, so I clamped the wire to the shroud and put the other end in the ground hole in a socket strip. Is that the best way to ground it? The volume and sound quality are greatly improved since grounding it! To make absolutely sure the grounding is what did it, I unplugged the ground wire and the loud hum came right back. Bingo! Thanks, Marc.

Rather then "grounding" it, try just turning the power plug over--- MAY accomplish the same (or better) thing. Ron Rich

Sorry, I misread the post. I didn't notice that you already had it to the shop. Grounding or reversing the plug certainly can fix a hum. I'm glad it worked out for you. I myself do not trust old E-caps. I replace them all regardless of how they test as I know of a few that gave no warning before they gave up the ghost. My Boss also experienced this with his Bogen. Luckily, it did no damage except that it took a few years off his life when it blew.