CD66 stuttering

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21-Oct-2018 08:06 PM

Ton

Ton

Posts: 37

Hi,

I have a CD66 that starts stuttering during play and several times just randomly stops playing.

On diyAudio I read a post saying that dropping a little oil in the disc motor could solve this.

Does anyone have any experience with this ?

And to reach the disc motor, at least to a point I can oil the spindle motor front bearing, do I have to disassemble the complete CD mechanism  as described in the CD66 Service Data manual ?

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23-Oct-2018 06:07 AM

EJP

EJP

Posts: 1530

It looks like both the laser and the platter spinning motor come up from underneath the assembly shown on page 14. I believe you will have to remove the drawer (101) and tray (104) to get to the spindle for lubrication. Don't disturb the laser other than to clean it with a camera brush.
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23-Oct-2018 10:10 PM

Ton

Ton

Posts: 37

Hi EJP,

thank you for the explanation. I will give it a try and use a can of compressed air to remove the dust and I will use a drop of bearing oil I got with my turntable, I think that oil will be suitable.

I looked on the internet for some more articles and found quite a few stating that the skipping and stuttering can be caused by the clamp that holds the cd down. 

This article on audiokarma.org gives a nice explenation how to solve this (on a CDM-4/19 in a Philips CD60, but I think it’s the same for a CDM-4/16 in a CD66).

So I will give that a try too.


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28-Oct-2018 05:10 PM

Ton

Ton

Posts: 37

Dropped a tiny bit of oil in the spindle motor. On the laser, I only used a camera brush and compressed air to remove some (invisible) dust , didn’t use alcohol or cotton swab.
Used a
magnifying glass to look at the  laser, I saw no scratches, surface looked ok.

Then a tiny little bit of grease, hardly visible, on the pivot points of the flap (grease there was crackled), also tiny bit on the drawer’s rail and on the hinge that activates the button when the drawer is pushed inside(also cracked remains of grease).

For a moment it looked like the stutter was gone, three cd’s played without a problem, but from the 4th on the stutter is back, most of the time after track 5.

I did the voltage measurments from page 12.

First the Laser Current Adjustment across R3501 (TP1 and TP2), a  4K7 resistor (measured 4788).

I have no Philips test cd #5 at hand, so I used three different audio cd’s. The voltage started at 50mV and it counted down 1 mV every few seconds, and it stabilized between 26 mV and 36 mV depending on the audio cd and the track played.

According to the service guide it should be 50 mV +/- 10 %

Does this mean the laser is at its end or just not set correctly ?

Then the Focus Adjustment between chassis (TP4) and a wire link (TP3). It constantly changed value, so I did a min/max measurement.

track 1 first minute min max values in mv:  cd1 382-386  cd2  385-393  cd3 368-374
track9 first minute  min max values in mV: cd1 340-470  cd2   320-460 cd3 340-440

According to the service guide it should be 400 mV +/- 10 %

So that looks almost spot on.

So first question, does someone has track1 of the philips test cd for me ? Then, anyone an idea what can cause the stutter ?

Regards, Ton
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30-Oct-2018 10:30 AM

EJP

EJP

Posts: 1530

The Phillips test CD #5 costs several hundred bucks, and the reason is that it isn't about the content, it is about the actual physical recording. What you are adjusting to is a certain light level, refractivity index, etc. Nothing to do with the bitwise content. So merely copying it would achieve exactly nothing.

In practice I haven't had to do anything to my CD67 in 25 years other than tweak the drawer height and replace a couple of orange idler wheels. Best to leave well enough alone.

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30-Oct-2018 10:05 PM

Ton

Ton

Posts: 37

I want to stay away from both trimmers as far as possible, because I believe I could do more harm then good, but I still have a stutter and often a complete stop.

And that won't go away if I do nothing, so  what is left for me to try. 

I haven't lubricate the part that move the optical pickup/sled, so perhaps that is an option to try.

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