Dynamo Hum Has Haunted my Dual 1241

JJCalvillo

AK Subscriber
Subscriber
This is a strange one!

Have a hum from my Dual 1241 and Grado Green, with both my Marantz 2215B, and Denon DRA-425. Both my Denon & Pioneer tables (one sporting a Grado Blue and the other a Grado Black) have no hum with those 2 receivers .

I changed the channels into the Denon DRA-425 and the hum is still in the right but now the left as well, which would make you think it's a receiver problem, except for the other tables working fine with the Denon, and the Dual has problems with the Marantz receiver also.

I've cleaned the contacts on the cart., the plugs, the contacts on the little board in the clamshell, and the RCA contacts, messed with the ground (on, off the Denon 425) then checked the ground to the underside of the table.

Also, I found this shot of 1241 clamshell on vinyl engine and mine doesn't look like it.
V.E. 1241 clamshell=
DualShell.JPG

My Clamshell is different, no metal prong from the roof for a ground.
MyShell.JPG
Looks like my clamshell has a different type of ground. Maybe they changed design in the middle of the run? Someone did a Dual arm transplant? Who knows whether it's even supposed to be on a 1241?


The RCAs look pretty cheap and I'm thinking of replacing those to see if they are the problem. This leads to a couple of questions.
• Anyone done this? Looks like I have to clip the wires where they attach to the table and solder on new ones.
• Any recommendations on good but not especially expensive RCA's? Got the table for $40.
• Do you think I'm barking up the wrong tree with the RCAs?
 
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