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Changed first cartridge and broke something

Discussion in 'General Audio Discussion' started by Aladdinsane, Mar 11, 2018.

  1. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    So, I just picked up a music hall mmf 2.1 from a friend. The cartridge on it was the one that came with the table, and I wanted to change it to a Pickering xv15 that I had on another table. (Note: never done this. Still a newbie. But I understood the concept and nobody made it out to be a difficult procedure, so I figured I was fine. I was not.)

    So I got both cartridges off easily enough, but failed miserably at trying to install the Pickering on the music hall. The screws for the music hall head shell were too long to work on the Pickering.

    I actually dropped the Pickering face down on the turntable at one point. Not sure how much damage this did to the stylus, but I'm sure it can't be good.

    So after stripping the screws to oblivion I decided to just put the music hall cart back on. Did that and realized I had no idea how to wire it. Tried a few different combos before I got one to work. Was playing fine for a few minutes...

    And then my speakers started making this loud humming noise, and the music stopped playing. I can make the humming stop briefly by tapping on the turntable, but it just comes back and I have no idea what to do.

    Did I mess up the wires? I didn't have tweezers or needle nose pliers so I was using regular pliers on the little wires. I was being gentle but maybe not gentle enough? Any help would be greatly, greatly appreciated.

    TLDR: changed cartridge, now there's a loud humming noise coming from speakers and music won't play.
     

     

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  2. slimecity

    slimecity Super Member

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    If it was playing and tracking OK for a while your stylus/cantilever may be OK.

    Just sounds like a bad connection with one wire. Ensure the headshell is tightly screwed onto the arm. Check your wires again, ensure the cartridge wires are all well-connected to the metal sockets. Ensure that the sockets are well forced up and all the way over all the pins
     
  3. Blue Shadow

    Blue Shadow I gotta get me a new title

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    Start by getting the manual and note that the wiring is color coded on the arm on the mmf. There should be markings on the back of the cartridge, too whether that be the use of colors or letters or both. Not to hard to figure out.

    https://www.vinylengine.com/library/music-hall/mmf-2.1.shtml register and free dl of the OM.

    Quite a few manuals, Owners and Service, are available on the web. Hunt those down before jumping into a new project. If there is no manual, ask on AK we help everyone.
     
  4. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    Thanks! The good news is I had the wiring right. The bad news is the hum is very much still there.

    On the troubleshooting section it says a loud hum could either mean a ground loop or no earth connection. I don't know what either of those things mean, could you explain? It worked perfectly fine before I removed the cartridge, so it has to be something to do with that.

    If it helps I think I even know which wire is causing the hum. It's the white wire. I can make it stop by fiddling with it.
     
  5. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    21,438
    Location:
    SE PA
    The hum is coming from a lack of continuity, not a ground loop.

    What you have is a common phono problem. The wires that carry one channel to the amp are for example Left hot and Left gnd. One of these not making contact causes hum. Similar for the right channel. Another way there can be hum is if the ground connection, a separate wire on most turntables, is disconnected. One some turntables this ground is part of the ground for one of the signal wires, say attached at the tt to the ground of the left channel. Any loss of these grounds will cause the hum you speak of. Since you are implying that both channels hum, I would investigate the last option. Turntable, arm and chassis all grounded together and that needs to get to the preamp ground connection (by the phono inputs) or connected to the ground of one of the signal wires. Get meter check for continuity is how I would look into this if you are sure that the table does not have a separate ground wire and you left it disconnected.
     
  6. musichal

    musichal poet emeritus Subscriber

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    Norman OK
    Your headshell wires aren't making proper contact, most likely, since that is what you changed. It only takes one. Clean the terminals and pins and reconnect carefully.
     
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  7. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    Thanks for the help. The sockets are forced as far as they can go. Headshell is screwed on tight. It's definitely the white wire that is causing the hum. Could I have pulled it off of the metal piece that connects to the pin? If so should I snip the wire and strip it and re connec
    Informative. Thank you for the explanation. The table has a ground wire that goes into the receiver, is that the same one you're talking about? That was connected.

    I found the problem, it was in fact the white wire where it was soldered to the pin connector. I must've partially disconnected it when I was finagling it with the pliers. I pulled at it a little more and it came right off.

    So, I'm going to resolder it to the little connector, and hopefully all will be good. Does that seem reasonable enough? Is there anything I could be missing?

    As someone new to turntables, those wires to connect the cartridge seem like a major design flaw. I'm sure some tts must have this, but it seems like it'd be SUCH a huge improvement to just have the wires contained in some kind of plug that you just plug the cartridge into.

    Anyway, hopefully all goes well.

    So I resoldered the wire, cleaned all of the connections, reconnected them carefully and there is still a hum in the left channel.
     
  8. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    Do you think the wire could be broken internally? Should I snip off the end and then strip it and resolder it?
     
  9. Blue Shadow

    Blue Shadow I gotta get me a new title

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    Now it is time to use that free with any purchase from Harbor Freight digital voltmeter and check continuity with the ohms setting. The major causes are the RCA plugs broken connection of the signal or ground at the plug and the headshell leads you have found. Sometimes there is a problem with the wiring from the arm to the wires going to the amp but not as frequently. Many times these small wires will have issues. This is why a meter is helpful.
     
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  10. musichal

    musichal poet emeritus Subscriber

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    What Blue Shadow said.
     
  11. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    So, I stripped and resoldered the left positive cartridge wire and all is back to normal. Woo

    Thank you all for your patient and informative advice. As someone who considers himself to be pretty handy this was very frustrating. Definitely a good learning experience though.

    Might pick up a volt meter just to make sure I didn't mess anything up, but based on the sound I think I should be good.

    Again, thanks for all the help. You guys rock.
     
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  12. musichal

    musichal poet emeritus Subscriber

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    So how did you set overhang? Do you have a protractor or maybe a gauge?
     
  13. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    Just a protractor. Didn't really dial it in at all yet honestly. My receiver is on the fritz so I won't be listening to any music until I figure out what's going on there anyway. That's a whole other discussion though...
     
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  14. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

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    They do have those...it's called P-Mount. Basically pins on the cart and a socket on the end of the arm.
     
  15. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    Haha yeah I realized later on that that's what a p-mount is.

    What's the consensus there? They don't seem very popular. Do p-mounts produce lesser sound quality, or is the main down side just that there aren't as many options for cartridges?
     
  16. Todd Dodds

    Todd Dodds AK Subscriber Subscriber

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    The P-mounts are for small children, sexual deviants, lower primates, and those with several missing fingers. But you are a born turntable technician, so you'll be wanting to stay with standard 1/2" mounts. If you find the tiny little wires frustrating, just wait until you get the Big Idea to re-wire a tonearm. Embrace the frustration for it makes the music sweeter.
    You'll also enjoy the myriad sizes and threading of cartridge mounting screws as you get more involved with swapping carts. I spent 20 minutes trying to get a nut threaded before I realized I'd picked up a random nut that looked to be the right one.

    Good luck with your receiver, looking forward to that thread ;) .
     

     

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  17. Blue Shadow

    Blue Shadow I gotta get me a new title

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    Non-p-mount cartridges have differing pinouts and pin spacing and in some cases pin sizes. There are some more solid headshell wires out there but since many are looking for lightweight in this area, most cartridge leads are not heavy duty. some are even part of the tonearm on arms without a headshell.

    As Todd said, there are many decent p-mount cartridges and no very good ones. All for lesser tables. Even if the table is a grand and uses a p-mount it is still lesser. Some folks have multi-thousand buck cartridges one several hundreds of dollar tonearms and something that spins the record beneath that.
     
  18. Aladdinsane

    Aladdinsane Active Member

    Messages:
    131
    Hahaha. Oh it's coming soon don't worry. I'm going to clean it (again) tomorrow and see if that takes care of anything, but if not that's about the extent of my receiver repair knowledge.

    Man I wish I could afford working gear. Some day...
     

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