Yamaha YP-D6 direct drive wow and flutter

[Carlp]

I have a direct drive (Yamaha YP-d6) that has a clearly audible wow and flutter. It's rhythmic and steady, and I can watch the strobe hold steady then speed up, then hold steady, then speed up again, perhaps once a second or two.

The TT was from a smoker and was shipped to me with platter attached (taped in place), poorly packed. At this point I'd like to know if it's likely I'd be able to fix this, as I need to contact the seller and figure out if he'll take it back (his cost, not mine) if not. Also, some thoughts on whether or not the shipping could have caused the problem (bent shaft, damaged bearings, etc.). Or is this a case of "sold as is, buyer beware" (though that was not stated in the listing).

What's the most likely cause of wow and flutter (the original and well maintained yp-d6s are pretty good in this repsect from what I've read)? Old, hardened or dried lube? Bad bearings or worn commutator or armature? Speed controller problem?

Thanks!
(btw, I have sprayed the speed adjustment pots with contact cleaner b/c speed jumped erratically when touched, and this problem is mostly cured. But the W&F still exist.

[kevinkr]

Does the speed vary with every revolution of the platter or just randomly? With the table not powered up if you turn the platter by hand does it rotate smoothly or bind at some point in its rotation?

DD motors are electronically commutated by hall effect devices so there is no physical commutator. The drive coils are fixed, not moving..

The issue could be mechanical or electrical in nature.

Unless there is something special about this table I would see about returning it.. Usual mechanism if the seller is difficult or insists on terms unfair to you would be to open a dispute through paypal.

[Carlp]

Thanks, Kevinkr. Nothing special about the table except the price is right if I can get it working. I am looking for a DD turntable but have very limited finances for the purchase. This one fit the bill...except for the speed issue. Also, I hate to let anything go to the landfill that doesn't need to.

Basically, the strobe marks advance then hold still, advance then hold still, etc. etc. On a roughly 2 second cycle - basically once per revolution. I can get it to bounce around but not actually advance if I slow it down every so slightly. Same thing occurs on the 45rpm setting. There may, though, be a random variation on top of that, as it sometimes seems the speed variation isn't exactly the same each revolution. Sometimes the variation is more abrupt than others. The strobe dots aren't strong and I have an astigmatism that I think makes viewing them carefully a little challenging.

As for binding up, there's nothing I can feel when spinning the platter or the spindle by hand, though the spindle feels a little sluggish by hand (platter spins for a reasonably long time, maybe 15 seconds from 33 1/3rpm). There may be a tiny amount of wobble in the platter, up and down along the outer edge relative to the plinth, but not much. Spindle seems tight.

Thanks again.

[kevinkr]

Hi Carl,
This sounds like an electronic issue, given the age of the TT I would not be surprised if all of the electrolytic capacitors need replacement - at least it does sort of run.
How good are you with a soldering iron?

I also recommend you check out Vinyl Engine | The Home of the Turntable for further advice and hopefully a manual. You will need to join to get access to the library.

[h_a]

Hi,

all of that sounds a bit like a problem that's hard to fix; this unit does not appear to be quartz controlled, so it might indeed be a speed controller problem.

As I understand this fault wasn't stated, so I would return the unit. It is from the late 70ies and it is likely that some more work might be needed (aside from actually fixing it, like replacing the caps) to get it back into perfect and reliable condition. I did this several times and would recommend it only if the unit works 1A otherwise.

Hannes

[Carlp]

Thanks all. I can sling solder pretty well and am a member over at Vinylengine, but haven't found much help there yet. I'm leaning toward returning it at this point (the fault wasn't stated but may have occurred in shipping). But Hannes, if you have done similar work, can you explain the basics of fixing something like this? It isn't quartz lock or PLL (as far as I can tell, but I don't know much about determining this). What other mechanisms would be used to control the speed, and how would one go about fixing it?

Thanks,
Carl

[h_a]

Hi Carl,

I don't know this particular unit good enough to give you practical advice; in phase-locked models there's usually a crude non-locked speed regulation circuit that starts the platter and brings it to speed within the window of the locked loop. When the speed arrives there, the PLL kicks in. The important caps in the PLL are usually film types, so unproblematic in terms of aging.

It is not obvious to me as to how such a defect might develop during shipping; any case, you can only try to trouble shoot it with the service manual.

Hannes

[Carlp]

Thanks, Hannes, I know it's hard to troubleshoot remotely, but I appreciate your thoughts.

I guess at this stage I'd only like to know what are the potential problems that cause varying motor speed in an old (1970s?) DD turntable:
--speed controller
--motor and spindle lubrication
--drag from semi-automatic mechanicals (gears, etc. or old, hard grease)
--bad motor
--other?

Any guess on how likely the problem is a bad motor that would require me to find a new motor? Sadly, I haven't found a manual at vinylengine or anywhere else online (free only at this point - don't want to spring for a manual for a table I won't keep).

I'm going to try to return it today or tomorrow unless I can convince myself I can fix it. Thanks for all the help.

[kevinkr]

Hi Carl,
Were you successful in your bid to return it? Or did you decide to keep it instead?

[Carlp]

I'm in the midst of discussing a return. They think I should pay return shipping. I think not, as their truly lousy packing job may have caused the problem (no way to know for sure). I'm not sure where it will end up.