Pioneer Platter Scrapes or Grinds

Andyman

Andyman

Scroungus Stereophilus
Subscriber
I'm trying to hook up a guy with one of my Pioneer PL-112D turntables so he can burn his LPs to digital and have an issue; the platter grind because it scrapes the plinth at points.

This turntable has a suspended motor tonearm and spindle all on a sub-chassis which my guess is spring loaded; well, it bounces. It seems that the springs may have weakened because there are point where the bottom of the platter will engage the top of the plinth and make a scraping sound. I have two and they both have the same issue, so my guess is that i'm not the first to encounter it. Maybe I'm the first who wants to fix it on such an inexpensive table, but I know I'm not the first to run into it.

So, has anyone remedied thsi and if so how? Better springs, grind the platter, shim up the platter on the spindle, screw in a transit screw to limit the suspension? I've thought of all that so let me know what's works/worked for you and we'll get another guys records spinning.
 
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Andyman,

Where is the main bearing in the scheme of things and why is it not a possible culprit?

Can you determine whether the platter/spindle/bearing wobbles independent of this suspended sub-chassis?

Then again, a PL-112 owner may zero right in on the problem with little troubleshoot & guesswork.

- Mario
 
This is an entry level turntable and the bearing, if there is one, is in the spindle, and seems fine.
It's pretty clear that the suspension seems to be sagging a bit and to the left as the far left side drops more than the right by the tonearm. I'm thinking of tossing a transit screw in there to hold it up so he can get his records burned.
 
Andy - seems like there are three screws underneath that have some adjustment in them for the suspension. It's not much but may be enough to keep the platter from scraping while playing. You have to pull the bottom panel to get to them.

I have a PL-115D that does the same thing but only when I set the cleaning brush on it - does not scrape while playing.

Alan
 
i had a pl112d that i got up and running and eventually gave to a close friend who desperately needed a deck...
its a long time ago..but i remember the platter was quite low and if i remember rightly it also scraped...i think you can remove the bottom panel and access the suspension springs...i can't remember if you tighten a screw or something..but i do seem to remember that it is possible to raise the suspension somewhat..either by rotating the springs..or tightening them slightly via a screw on each spring assembly...i'd try to find a way of supporting the deck right way up on a level surface and use a spirit level to ensure any adjustment is level with the plinth...as it took some time to make it level once it stopped scraping
sorry if my memory is hazy..but i think the adjusment isn't too complicated..
i'd recommend asking someone who has disassembled the bearing for advice before lubing it..as i seem to remember finding it awkward to do..
 
Many Pioneer belt-drives, including the 112D, has a thin thrust bearing at the bottom of the platter bearing well. It looks like a small flat spacer but it is part of a bearing. It is very common for these to dry up with age and to crack or shatter into small pieces. Sometimes the center of it wears out and there will be a noticable dimple or depression in the center. When this is worn or broken, the platter will often scrape or grind.

May I suggest you locate and purchase a service manual? It will show you how to replace this part and the required dimensions should you have to have a new one manufactured for you. (I've replaced several and cut my own parts using a precision milling machine and Delrin bar stock.) The manual will also show you how to adjust the suspension should that be the problem (and it is the first thing you should try, anyway).
 
I really don't think it's the bearing as the entire sub chassis seems to sink, although if the worn bearing were to cause the spindle to sink, that would consequently cause the platter to follow and ride lower, so who knows.

I did pull the bottom plate and saw the 4 springs supporting the sub chassis. I pulled one and it looks like if I add a washer as a spacer/preload it should raise the unit enough to mitigate the scraping. Tightening won't affect it as the spring mount uses a shouldered bolt and it's snug already and not going any further. An interesting discovery was that in the first unit, which is the worst scraper, the platter mat weighs 12.2 oz; on the second it weighs 7.0 oz; almost half as much. or over 140 grams less which is more than the 120 gram or so a normal lp weighs in at. So it looks like Pioneer saw an issue and addressed it to some extent by using less of a mat. BTW, that first on really weighs a ton; it's the heaviest mat I recall dealing with.
 
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