Yamaha P-(X)50 Turntable DIY Maintenance Thread P-350, P-450, P-550, P-750, P-751, P-10, P-20

Discussion in 'Turntables' started by reydelaplaya, Aug 14, 2016.

  1. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    The plastic on the hinges is a common fail point where the tension spring finally breaks through. There's a fix around here somewhere where holes are drilled in the plastic and a brad/fine finish nail is passed through creating a new support for the tail of the spring.

    There are also several different, all-metal hinges that from different manufacturers that will fit. I know some model of JVC TTs fit because that's what I'm using on my own. Linn also fit, but they're kinda expensive.

    Check the auction sites for TT hinges, and look for the correct shape. The only thing needed to be a perfect fit is a couple of felt shims.

    [​IMG]
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  2. Broton

    Broton New Member

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    WOW. Simply amazing. Thank you so much for that effort. I look forward to try this... need some time and space. But looking forward to seeing if this does the trick.

    Thanks again! And I never heard of organdonorparts great site.
     
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  3. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    You're welcome, @Broton. I hope that it's an easy fix like I've described. That's a great TT from Yamaha in that model line - in fact, I think it was probably their top of the line from that series - with the 750/751 being a close second. I think it's definitely worth trying to repair and hang on to for a while. Let us know how it goes. And if you run into any problems, just post in here.

    As for your intermittent sound from the cartridge, try gently unplugging and re-seating the cartridge wires. Sometimes it's as simple as a poor connection back there.
     
  4. Broton

    Broton New Member

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    6
    Well... I did my best. As instructed... and sadly to no effect. It looks like the plastic feet and the motor housing is in there solid. No play whatsoever. Backed out the screws and tightened again. Still rubbing. Also... there now seems to be a bit of "steppyness" to the motor when running. I have never run the motor without the platter before... but there seems to be a bit of give and go to it's movement. Was it there before? I cannot say... but don't recall. Maybe that's how it should turn. My feeling is not... I assume the motor should rotate constantly and silently. Probably made more of a mess of my situation. Le Sigh.
     

    Attached Files:

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  5. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    Don't give up, we're not done yet.

    As for the jitters, yeah, the motor needs the platter mounted in order for it to stabilize its speed. It uses the momentum of the spinning disk to help maintain proper speed. When the platter isn't there, it gets jerky. My 751 does the same thing without the platter, too. If I've learned correctly here in AK, it's the space between the poles of the motor that causes it.

    So it still scrapes?

    Hmmm... And you didn't notice any other screws or anything that looked loose while you were in there? From what I see in the pics, probably not.

    Your platter just has two thumb holes in it, right? No big open gaps like shown below? (Pic courtesy of OrganDonorParts)

    [​IMG]

    That's a Yamaha P-350 belt drive platter. It should physically fit more or less, but not really work properly.


    The only other thing I can think of is if all screws and mounts are tight, then maybe the ball bearing of the spindle has been significantly worn down to the point where the platter loses that needed height to prevent rubbing. The ball of the bearing rides in that round thing in the middle of your motor, here:

    [​IMG]

    It's a very small clearance between the platter and the chassis. If a prior owner repeatedly ran it with something heavy there (record weight comes to mind). It could have prematurely worn down the bearing.

    [​IMG]

    If that's the case, and you feel it's worth it to fix, that motor is still available on organ donor. You already see it's only a few screws holding it on, the only additional step would be to solder a few leads. That module would replace the spindle and bearing, along with the whole motor.

    But, the flip side is that there's a possibility that it may make no difference at all - and that's a tough call.

    Let me have a look at my 751 again and see how tough it is to check that bearing.

    I'll log back in here in a while. But like I said, don't give up yet. I'm sure it's still fixable.
     
  6. Tcomisky

    Tcomisky AK Subscriber Subscriber

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    Hi, how about a grinding sound coming from a Yamaha YP-B4? I picked it up yesterday and the seller assumed it was motor mounts causing the noise, I've taken it apart and looked, it does not appear to be the motor or the mounts. The sound appears to be coming from something rubbing on the large plastic/teflon R-Gear or the actual main shaft itself?
    It almost sounds like a low clicking sound, like a baseball card in bicycle spokes?
    I'm thinking maybe it needs silicone grease (does white lithium grease work well on these?)?

    The sound goes away when the platter and belt is removed, I can also similate it by spinning the platter by hand with the belt removed, so that elimates the actual motor from the equation.

    When I turn the main shaft by hand, when it's free from the r-gear assembly, it sounds like the issue is with it.
    I can hear something odd with it. Here it is in the first photo. I assume I need to take off this metal bracket to remove the shaft and see what's in there? So, before I do, what IS inside there? Lol is it a single ball that it rides on? What should I use to grease it if I get it all apart?

    Thanks.
    Tom


    IMG_9501.JPG


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    Here is the top view of the main shaft:


    IMG_9497.JPG


    IMG_9496.JPG
     
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  7. Tcomisky

    Tcomisky AK Subscriber Subscriber

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    Nope, no bearing in there that can be accessed, but now that it's removed, it doesn't seem to spin with any issues, although it does have up and down play in it..

    I cleaned up all the old grease that was on the gears and will re-grease it all tomorrow and see what happens.

    IMG_9502.JPG

    IMG_9503.JPG
     
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  8. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    Wow, you got that out of there pretty quick! LOL I'm still not sure what would be causing the sound you describe. But if you can't hear it on just the spindle and bearing by itself, there's a good chance it's coming from one of those plastic tracks/gears like you mentioned.

    The spindle sits in a pocket and rides on a single lubricated bearing, usually a ball. The up/down play you have is probably normal as long as it's not excessive. As for lubricant, there is stuff called bearing grease that you can get at an auto parts store, though I believe others, including myself, have used a light machine oil with success.
     
  9. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    I've got an idea.

    If you have access to a caliper gauge,
    [​IMG]
    you could measure from the back of the bearing cup to the top of the spindle and ask the folks at Organ Donor if they would do the same on the motor they have. If theirs is longer by a mm or so, it may be your best bet to get theirs, because if so, it could signify that your bearing is indeed worn significantly enough to cause rubbing. I'm certain they'd be happy to do that if you explain why.

    I'll probably have a chance to pull mine back apart here tomorrow afternoon to see how tough it is to disassemble that motor and get at the bearing.

    I'll post pics and let you know. :thumbsup:
     
  10. Tcomisky

    Tcomisky AK Subscriber Subscriber

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    Location:
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    Well, it's turns out to be what was originally, it did quiet down a bit with new grease and gear adjustment, that took care of the clicking, but there is a definate motor rumbling. I can put my hand on the motor and feel it.
    The rubber bushings seem to be pliable and soft. I put some shrink tubing on the studs thinking that may help.
    Maybe I do need new rubber bushings, or some sort of rejuvenator. I have some stuff I bought from BMW for the rubber seals on my convertible, I may try that..


    IMG_9554.JPG
     
    Last edited: Mar 30, 2017
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  11. ex-musician

    ex-musician New Member

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  12. gunsha

    gunsha New Member

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    12
    Hi, after 1 year I have finally set up my Yamaha P-750 on a decent rack in my new house, only to find that it is stuck in 45 rpm speed.

    First I thought somebody spilled juice into the switch, but when I opened the base cover I saw the switch is mechanical and out of the way from spills and engaged fine. It's a simple on-off toggle switch. Not sure if 33 is on or off. I didn't have my voltmeter, and desperate I tried the following test:

    1) shorted the pins on the switch, made no difference.

    2) cut one of the wires that god from the PCB to the switch, sadly, no difference.

    I was really hoping that the cutting of the wire would get it stuck in 33 so I could listen to my LPs. But no luck. 45 all the way, quartz locked exact.

    Now what could it be? Why would anything but the mechanics go bad from sitting for one year in a corner?
     
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  13. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    Welcome to AK, gunsha.

    I wish I had some good news for you, but unfortunately I don't. I also have a P-751(750) that is stuck in 45 RPM. And just like yours, it happened with no warning. One day, after being used with no issues the night before, it just stopped working in 33. See thread below.

    http://www.audiokarma.org/forums/index.php?threads/well-crap-yamaha-p-751-stuck-in-45.721233/

    I have gone through different areas of its electronics, re-flowing solder joints on connectors and chips. But ultimately, nothing changed.

    That one has since become the model for most of the pictures included in this thread. It has pretty much been cleaned and refurbished during this process, and if I ever find a replacement controller board, will be a great runner. But as of yet, no replacement board has shown up over at Organ Donor Parts - takes a bit of luck to find an almost 40 year old part.

    [​IMG]

    I liked it so much, though, that I took a chance and bought another P-751, which is currently in use with no problems. (There's a P-750 in its box currently on eBay that looks to be a good deal if you're willing to take a chance on another. I would, since you've already got the one you have that can be used as spare parts should anything need to be replaced in the future. But that's up to you.)

    I'm sorry, but besides getting another 750, I really don't know what else to tell you other than keep checking www.organdonorparts.com and see if that control board finally surfaces. I wish I could help you more. If I do get it figured out, or find the replacement IC chip that controls the speed on that board, I'll PM you when I update this thread with the how-to.
     
  14. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    I was just rereading that thread, you may consider checking the two capacitors and that resistor which @bobins08 suggested below. I didn't, because I don't have a multimeter, and ended up buying another TT, but he's probably on to something there.

     
  15. BakedTater

    BakedTater New Member

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    Location:
    Missoula, MT
    Rey,

    Thanks for all the info. I've got a P-550 that functions well with the exception of the pitch control/motor speed. It tends to run just a tad fast, and when I dial it down toward the sweet spot it speeds up erratically before eventually reaching the speed at which I started.

    I've never worked on a TT before and I'm not sure if simply replacing the pitch control mechanism will solve this. There's one on OrganDonor right now. Any advice would be much appreciated.
     
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  16. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    Hi, welcome to AK. Glad to see you found this thread! You have a very nice turntable - I really would like to get a 550 sometime.

    As for the pitch control, that should just be a potentiometer, or variable resistor.

    Since you know you have a backup waiting on organdonor, if you feel like taking a chance with the one you have, try using some Deoxit to clean the contacts on the inside first. First, unplug the TT from the AC power. Then see if you can find any access points where you can direct a spray to the inside of that housing. If you can get some spray in there, give it a good shot, then work that wheel from lock to lock for a minute or two while it's still wet to clean the whole contact area inside.

    That should probably work. If it does, you may consider following up with some faderlube to make that wheel smoother turning and prevent future corrosion on the contacts.

    That said, the cost of those two cans of contact cleaner/treatment might be about the same as the price for that pitch control on organdonor.

    If you want to try a little test right now to see if it might work ahead of any purchases, just give that wheel some exercise back and forth for a minute or so, and see if that makes any difference in dialing it in to proper speed. If you can get it closer to correct speed, a good contact cleaning with Deoxit should do the trick.

    *If you use contact cleaner, do not plug your TT back in until it has completely dried - that may mean overnight since it's an enclosed potentiometer.*

    Good luck! Let us know how it goes.
     
  17. BakedTater

    BakedTater New Member

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    Location:
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    I tried working the dial through its full range for a little while, then got it centered at the correct speed. When dialed to the desired speed, it plays well for a bit, then speeds up and slows erratically to the point of bending the pitch. If I set it just a tad fast it keeps a consistent speed. Any ideas?
     
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  18. reydelaplaya

    reydelaplaya AK Subscriber Subscriber

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    It really sounds like an internal contact problem in it. I'd start with a Deoxit clean of the potentiometer and see where that takes you. Since you can get it dialed in, even for just a minute, a good cleaning is probably all it needs.

    However, it's not likely that you'll find another replacement one any time soon. At the price they're selling that one on organdonor, I'd really recommend getting it before it disappears - if for nothing else, just to stick in a drawer in case you need it in the future.
     
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  19. gunsha

    gunsha New Member

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    OK I have done this process twice now and each time I didn't read the instructions here to follow them correctly. I have to stress that this issue with securing the bearing screws ever so slightly is the most critical step. First time I tightened them too much which gave a hell of a resistance. And I thought that the bearings were still bad. Duh! Now I have it floating more freely. But I didn't perfectly center it because it seemed so hard with the lock nuts on. Yeah, should have left the lock nuts off for that process. Would be much better with a special tool for the lock nuts though.
     
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  20. BakedTater

    BakedTater New Member

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    I couldn't track down any deoxit locally but found some CRC QD Electronic Cleaner. Looked online and found that they're both hexane-based and that it should work the same. And it worked! Thanks for your help Rey!

    I'm still considering ordering the spare, any recommendations for other parts that may have a more limited lifespan? Figured I may as well stock up a bit if I put in the order.
     
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