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Old 20th July 2014, 04:26 PM   #1
SonyFan is offline SonyFan  United States
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Default CD deck spindle runout/wobble

I have a vintage Sony (of course) X33ES that I bought because I love the linear magnetic tracking of the KSS-270A mechanism, and as an added bonus it sounds excellent with some OP270FZ op amps and one gain stage omitted. I have noticed, however, a significant amount of disc wobble. It still plays fine even with this issue but you can hear what sounds like the disc hitting the lens every rotation, although I know this not to be the case since it isn't losing focus and is playing. I just imagine that the constant height adjustment is not good for the laser suspension, a particularly weak link in these NLA KSS modules.

Is this due to a bent spindle/shaft? What should I inspect and how would I go about correcting it?

Thanks in advance.
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Old 20th July 2014, 04:43 PM   #2
Mooly is offline Mooly  United Kingdom
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There should be no detectable "wobble" when a disc is viewed edge on. I'm not familiar with the model as such but there are only three real causes... bent spindle as you say, a platter that is not moulded true (the hole that the motor shaft fits into) and the easy one, some debris on the platter slightly lifting the disc. Poor platters are a common issue on many generic replacement mechanisms/motor assemblies.
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Old 20th July 2014, 06:35 PM   #3
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As far as I know the mechanism in this player is original, and the optical pickup surely is. I will check for debris as that would be a nice easy solution. The edge of the disc doesn't oscillate on it's horizontal axis, but rather vertically. It seems to have the symptoms of a dirty spindle, however a bent one would cause this motion just the same but I believe the edge of the disc would also move some should this be the case. The range of motion is rather extreme, 1-2mm at worst I'd say. The mechanism is physically identical to the KSS-151A albeit mated with a different tray, usually. If that information is of any help. Thank you for the reply!
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Old 20th July 2014, 06:51 PM   #4
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I have gone back and inspected the spindle what little I can with the unit assembled and it appears that it is quite dirty. The edge of the CD stays perfectly aligned, the well-printed labels on commercially pressed CDs follow a perfect arc when playing, the outer edge always appears to "wobble" since the dye is never even out to the edges. The very edge of the CD is also stable as far as I can tell by looking at the small clear ring on the outer edge. The spindle, when rotated by hand, shows no imperfections. My eyes may not be good enough to notice but it seems perfectly true. The spindle is covered in some sort of felt which has picked up a lot of dust/hair/dirt over the years and needs cleaning. I suspect that this felt has also worn in some areas which is causing some of the runout I am seeing. I am not up to the task of removing this material without chemicals for fear of actually bending the shaft, replaceable as it may be. It also appears that the clamping mechanism bearing moves quite a bit, I don't know if this is a result of being locked to the spindle when playing or if it is a problem all it's own. It looks quite cheap like any other I have seen, maybe it should be replaced. However, any CD player I have ever seen with such a "clamped roller" (as Sony calls it) exhibits this problem, no surprise given the piece is assembled with little more than a metal on plastic press fit joint.

Would it be ill advised to attempt disassembly of the mechanism for a proper cleaning? I am not too talented with mechanical systems, especially not in miniature as my experience is quite limited with them. I also possess another X33ES, fully functioning but cosmetically battered as a parts unit. I bought it for the laser but perhaps I can make use of some of the parts from its mechanism as well. When I get it back from my friend who is making custom side panels for it I will see if it exhibits any of the same symptoms.
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Old 20th July 2014, 07:00 PM   #5
Mooly is offline Mooly  United Kingdom
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Well stripping down mechanisms is all part and parcel of CD player servicing The runout you have, we are talking in an "up and down" plane when viewed edge on... yes ? Many discs look a bit suspect when viewed from above but that isn't normally an issue. The problem with platter imperfections are that the effect is magnified at the disc edge. A 1mm rise and fall at the centre part of the disc would be seen as massive at the circumference.

If you look on a scope at the focus error signal then it should show no low frequency component (which would indicate the lens was following a change in apparent disc height. If you have a CD that plays for near the maximum allowable time and you play the outermost parts then you should be able to visually confirm the lens is essentially stationary in a vertical plane.
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Old 20th July 2014, 07:45 PM   #6
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Yes, this runout is on the vertical plane only. It is the worst at the disc edge, hardly palpable near the center. I do not have a scope to check the error signal, unfortunately. All of my test equipment (of all things) was stolen from my dorm when I was away at school, right down to my cheap Klein multimeter. Whoever broke in left my laptop and watches, among other things far more valuable than my dated HP scope and meter. I know what you mean about the imperfection being exacerbated at the disc's edge, that is why I imagine that the spindle felt alone could be the culprit. Given my limited mechanical talent, I will probably change the whole mechanism out for the one in my junker, since all I really need is the pickup for the precious (and wimpy) plastic suspension and photodiodes that like to fail in these KSS-XXX/KSS-XXXX units. Should these problems manifest in the other player as well I suspect that it is the dirt and normal aging process for the felt that causes this. I still wonder about the roller bearing on the clamp, it seems to be extremely chintzy and I am suspicious of it. I will report back tomorrow or Tuesday when my sideburns are done about the other unit, hopefully it is working properly but it is even dirtier than this one on it's exterior. The junk unit has seen nearly twenty-five years of abuse and so much time powered on that the fluoro screen is losing lines and dimming and this brick-house of a CDP is still kicking. Not to mention both of these units survived shipping with an unlocked transport sliding back and forth at every turn and bump.
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Old 21st July 2014, 03:58 AM   #7
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I don't recall ever seeing more than just a thin sort of rubberise coating on the platter of the X33 series platters. I think that felt must have been added by someone, maybe attempting to silence audible slip on spin-up. You should be able to easiy see if the wobble is in the motor shaft or platter by simply putting the mech in the unloaded position, turning off the unit, then giving the platter a manual spin while observing the metal edge of it. If you see no wobble, then peel off the felt entirely.
NOTE: You should look up my other postings in threads about the X33es/x55es/x77es, regarding the Elna Duorex caps used all over the unit. These are absolutely bound to leak their corrosive guts out and cause bad circuit trace damage, esp. in the area of the dac & output stages, both on top and bottom sides of board. Leave those caps in place & you can count on the unit failing before long, possibly irreparably. I don't trust Elna caps in general(I trust only Nichicon and upper-gread Nippon Chemicons for long term reliability), but the Duorex series were just flat out defective from the outset, and are absolutely disastrous.
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Old 21st July 2014, 04:42 AM   #8
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Quote:
Originally Posted by stephensank View Post
I don't recall ever seeing more than just a thin sort of rubberise coating on the platter of the X33 series platters. I think that felt must have been added by someone, maybe attempting to silence audible slip on spin-up. You should be able to easiy see if the wobble is in the motor shaft or platter by simply putting the mech in the unloaded position, turning off the unit, then giving the platter a manual spin while observing the metal edge of it. If you see no wobble, then peel off the felt entirely.
NOTE: You should look up my other postings in threads about the X33es/x55es/x77es, regarding the Elna Duorex caps used all over the unit. These are absolutely bound to leak their corrosive guts out and cause bad circuit trace damage, esp. in the area of the dac & output stages, both on top and bottom sides of board. Leave those caps in place & you can count on the unit failing before long, possibly irreparably. I don't trust Elna caps in general(I trust only Nichicon and upper-gread Nippon Chemicons for long term reliability), but the Duorex series were just flat out defective from the outset, and are absolutely disastrous.

I have already done what you have described and rotated the spindle by hand and noticed no runout. That is why I think whatever material that is on the spindle hub is the culprit. It may be deteriorating rubber, and appears almost white, slightly green, in color.

Also, the Duorex caps are long gone. Replaced with Nichicon you betcha!
I condsider re-capping anything 20+ years old preventative maintenance. Single op-amp per channel in the output, no headphone op-amp, motorized pot completely disconnected. Really sounds lovely. However, I can't tell the difference between the $10 fancy op-amps I bought (OP270FZ) and the common 5532s that came in it. I can tell the difference between one and two though, much more detailed with just one per channel installed. The output filter caps were changed for some .01uf fancy film capacitors I had left over from re-capping speaker crossovers, not sure it made any difference. No surprise.

Click the image to open in full size.

Last edited by SonyFan; 21st July 2014 at 04:45 AM.
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Old 21st July 2014, 09:12 AM   #9
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The clamping mechanism "bearing" is OK. It is there only to hold the mechanism while the tray is open. Please check the slack of the spindle motor bearings. They also could be worn out. If you replace platter, spindle motor, etc., be sure to measure the height of the platter before you remove it. Wrong height will cause a permanent mechanical offset on the lens suspension. You can check for the correct height by measuring DC voltage on focus-servo-out and compare it with the value in the service manual.
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Old 21st July 2014, 02:01 PM   #10
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Quote:
Originally Posted by franzm View Post
The clamping mechanism "bearing" is OK. It is there only to hold the mechanism while the tray is open. Please check the slack of the spindle motor bearings. They also could be worn out. If you replace platter, spindle motor, etc., be sure to measure the height of the platter before you remove it. Wrong height will cause a permanent mechanical offset on the lens suspension. You can check for the correct height by measuring DC voltage on focus-servo-out and compare it with the value in the service manual.
That bearing doesn't do anything when the tray is open.

Click the image to open in full size.

Thank you for the advice on adjusting the spindle, however I don't believe I could source a new one for this unit.
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