Turntable Restoration Questions

kevhed72
kevhed72 Posts: 5,059
in DIY, Mods & Tweaks
Working on the Pioneer PLD 115 and came across a couple of things:
1. Im installing new rca cable and have the option to run a new ground out from the unit to the phono pre. The original ground wire was attached internally to the wood bottom with a screw. Does either matter?
2. There are 4 rubber grommets and screws holding the motor in place. There is play between each screw and the grommets....motor will move up and down a bit. Does this require new grommets or is there supposed to be some space in there. Please see pics below:
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Comments

  • mhardy6647
    mhardy6647 Posts: 33,888
    edited November 2
    It is usually a good idea to ground the turntable to preamp to minimize hum, if that is the question you're asking? It needs to be metal to metal, though (of course).
    Hum and ground loops can be a challenge (as you likely know). If the tt does not have a polarized plug, reversing the orientation of the AC mains plug in the outlet can make a difference. A ground between the tt and preamp may or may not lower the hum level, but it is always easy to test!
    Sometimes, there are separate grounds between tt arm and the load (i.e., preamp, in this case) and between the tt chassis and the load. I look at grounding (and elimination of hum and certain kinds of induced noise pickup) as both art and science -- but that's partly because I don't understand the principles of grounding well enough. :#

    As to the grommets, there should be plenty of give in them (that's what they are there for) -- but there shouldn't be play in the way they're mounted. Rubber grommets are notorious for deteriorating.

    I assume the tt's a PL-115D(?). If so, the service manual, which may or may not be of much help, is available from vinylengine (if you don't have a copy already). Couldn't hurt. ;)
    https://www.vinylengine.com/library/pioneer/pl-115d.shtml


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  • SCompRacer
    SCompRacer Posts: 8,504
    edited November 2
    I agree with mhardy about the grommets. I've seen them shrink, harden and some even turn to goo. You could use some washers under screws to snug up the grommets. I wouldn't go too thick as to compress them too much. Overtightening a grommet can defeat the damping purpose it was there for. Doubt you'd ever find a new grommet like those. My local Ace hardware typically has assortments of small plastic and/or metal washers available.

    With table right side up, does the motor hang too low now where you may have a belt tracking issue without washers under grommets? If so, definitely get some washers.

    The ground screw that was attached to wood base, was there a ground from table attached?

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  • mhardy6647
    mhardy6647 Posts: 33,888
    Antique Electronic Supply used to sell a nice assortment of grommets for mounting record players -- but I doubt that they do anymore as they've been more or less totally focused on supporting the gee-tar (vintage, mostly) amplifier market for quite a few years now. :/
    https://www.tubesandmore.com/
    actually, they do have one size of phono grommet, FWIW, and a few specific replacement grommets. :|
    https://www.tubesandmore.com/search/node/grommet

    Might (???) be worth checking Radio Daze if one wanted some new, or backup (so to speak) grommets.
    https://www.radiodaze.com/rubber-grommets/ (none too promising, unfortunately)
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