• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Help me work through my new hum?

speedle

speedle

Peanut gallery owner
So, got the JICO SAS for the V15 Type IV, alignment process was a little fiddly but after a bit I got a fairly good result. Put the record on. Sounds ok, but what's this in between tracks? HUM!

It's definitely there and doesn't seem related to my hand being near or not. The trial and error process is made slightly more difficult on this SL-1700 Mk 2 because of the muting circuit, but I need to work through some structured sort of troubleshooting methodology before this drives me batty.

This cart was on the table when I got it, but I didn't use it due to the stylus being suspect. I've used my Shure M97 reliably with no hum issues, so I don't think it's structural to the table, but I've done lots of looking around here and can't find a way to start solving this problem.

Any thoughts? The headshell, screws, headshell leads, and phono cables are all the same ones, only the cart has changed.
 
Register to hide this ad
Clean the headshell connections with alcohol and make sure the connection is tight. Also double check the leads on the cart.

If you swap the old cart back in, does it still hum?
 
OK, so I swapped in a different cart, since my M97 is all hunky dory on the T35C and I really don't want to bother it. No hum from either my Empire or my Grado. BUT, note that I just connected the headshell leads to the carts, didn't actually mount them to the headshell. Cleaned the connections, plugged the Shure back in, and there's the hum. I really hope this V15 isn't buggered up permanently.
 
I've read elsewhere on here that sometimes that little ground tab on one of the pins can be touchy, or should be removed even. Maybe I should try that? Seems kind of extreme though.
 
All the time. This is depressing! I substituted a different headshell with a Shure M75 mounted on it, no hum. So, two headshells, two Shure carts, both headshells made of aluminum, with aluminum screws, but only one hums. I'll try cleaning the contacts on the headshell again. Electrically speaking, if I wanted to make an external contact with a little piece of wire, what on the cart should be connected to what on the shell?
 
speedle said:
All the time. This is depressing! I substituted a different headshell with a Shure M75 mounted on it, no hum. So, two headshells, two Shure carts, both headshells made of aluminum, with aluminum screws, but only one hums. I'll try cleaning the contacts on the headshell again. Electrically speaking, if I wanted to make an external contact with a little piece of wire, what on the cart should be connected to what on the shell?
Click to expand...

Nothing should need to be connected to the headshell except for the four leads. Any external connection you make would likely have to be done from inside the cartridge to have any effect, as far as I know. I would ensure that the posts on the cart itself are not corroded, and if possible try it on another table.

I don't have much else to offer; maybe someone more knowledgeable about this particular cart/table can advise?

We have more or less isolated the problem to the cart, or at least the cart/table combination, given the steps you performed above.
 
Yes, thank you very much for your help! I'm hoping the Technics experts will chime in, as I've discovered one more thing. All previous steps were performed with the table power switch in the ON position. When in the OFF position, there is still signal from the cart, but much, much less hum. And, only in the right channel does any of this happen. Lastly, now that I've isolated it that way, I can hear that even with the Pioneer headshell in place the same effect is there, just a bit quieter.

That all leads me to suspect the table. Bah! :(
 
I had a similar problem with a TD160 TP16 arm
Always suspected a loose tag connector but after a while I blasted & cleaned the collet connections with Isoprop, cleaned again - got some muck out. Then I found the headshell connector was not tight so wrapped some ptfe tape where it fits into the arm. Not sure which solved it but the hum went away.
 
OK, so things have progressed, but not necessarily in the right direction. After more substitutions, it hums with all combos of cart/headshell now, but only when the power is on. Power off, signal still gets through to the preamp, but no hum. So, I'm thinking maybe it's a power supply hum from the Technics. I'm thinking of just starting to take it apart, carefully of course, and experimenting, but haven't had any ideas past that.
 
You must log in or register to reply here.
Back
Top Bottom