Why does my CDM4 skip?

S.Spielbergo · 14th February 2009, 04:10 PM

I have a 1990 Proton AC 620 (philips based) with tda1541a and it sounds great but the transport has this anoying habit of skipping every now and then even when I play flawless CDs. I recapped pretty much the whole pc board and cleaned the laser lens but the problem persists. Since I don't know what I'm doing I haven't played with the adjusting pots yet, any advice?

stephensank · 14th February 2009, 10:28 PM

While a cd is playing, lightly feel for a bumping vibration in the top middle of the disc clamper, on top of the spinning hub. If you feel bumping or excessive vibration, you'll just need to pull the clamping arm plate, pop out the clamper hub & then sand flat the surface of the clamping plate that contacts the ball bearing in the top of the hub, eliminating the dimple worn into it by the ball. Once flat, use the finest sandpaper to get a finely flat surface, add some semi-thick grease to it & reassemble. Should totally cure it.

S.Spielbergo · 15th February 2009, 12:27 PM

This unit had a severe case of the pitting you described, I ended up doing exactly what you mentioned during the lass rebuild session. Just discovered that my reduced clamping force is the culprit, inreased it and problem solved...knock on wood.

Tino_diy · 17th February 2009, 02:44 PM

Sorry,
I have some skipping problem with my CJ DV-2b cd player, which uses a Philips L1210/11 tray loader and VAM1201 (I replaced it trying to fix the skip bits problem) and have noted that the clamp bottom
base is not very flat. Maybe that also my problem is due to the clamp?

Conrad Johnson DV2b skips

If that can be the problem, is it possible to do what stephensank wrote also on the L1210/11 clamp? But I don't see how to unmount it...
Thanks,
Tino

lu64319 · 28th February 2009, 04:52 AM

I suggest you to check lubricate on tracking mortor. Sometimes when the grease less will cause skip.

Tino_diy · 2nd March 2009, 02:04 PM

Hi lu64319,
I have tried many times to lubricate the different mechanics (VAM1201, VAm1202) I replaced, but that never solved the problem. This week-end I replaced all the mechanic (including the tray loader, for the first time) with a old CD12.1 and apparently there are no more skips on bought CDs, but with the CD-R burned at more than 74'. Probably the problem was on the tray loader (clamp not leveled) and I will try to add a VAM1201/J on this new L1210/11 loader...
I will update my original post when I will sure of the solution.
Thanks for your interest.
Tino

poynton · 2nd March 2009, 02:43 PM

Quote:

Originally posted by lu64319
I suggest you to check lubricate on tracking mortor. Sometimes when the grease less will cause skip.

Quote:

Originally posted by Tino_diy
Hi lu64319,
I have tried many times to lubricate the different mechanics (VAM1201, VAm1202) I replaced, but that never solved the problem. ..........

the grease on these mechs goes hard with age and causes tracking problems.

Clean ALL the old grease off including in the gears

NEVER REGREASE or LUBRICATE

Andy

Pano · 3rd March 2009, 04:47 PM

So you mean to leave them dry - no new lube?

Tino_diy · 4th March 2009, 06:54 AM

In past, I have found some problem with grease, but never with oil (specific for mechanical gears).
In any case, also with a new mechanic not lubricated I still had skipping problems, so my real problem was the tray loader...
Ciao!

poynton · 4th March 2009, 09:54 AM

Quote:

Originally posted by panomaniac
So you mean to leave them dry - no new lube?

yes.

If you want to use grease, there is usually enough on the side of your nose !

Andy

14th February 2009, 04:10 PM	#1
S.Spielbergo diyAudio Member Join Date: Jul 2007	Why does my CDM4 skip? I have a 1990 Proton AC 620 (philips based) with tda1541a and it sounds great but the transport has this anoying habit of skipping every now and then even when I play flawless CDs. I recapped pretty much the whole pc board and cleaned the laser lens but the problem persists. Since I don't know what I'm doing I haven't played with the adjusting pots yet, any advice?

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14th February 2009, 10:28 PM	#2
stephensank diyAudio Member Join Date: Oct 2006	While a cd is playing, lightly feel for a bumping vibration in the top middle of the disc clamper, on top of the spinning hub. If you feel bumping or excessive vibration, you'll just need to pull the clamping arm plate, pop out the clamper hub & then sand flat the surface of the clamping plate that contacts the ball bearing in the top of the hub, eliminating the dimple worn into it by the ball. Once flat, use the finest sandpaper to get a finely flat surface, add some semi-thick grease to it & reassemble. Should totally cure it.

15th February 2009, 12:27 PM	#3
S.Spielbergo diyAudio Member Join Date: Jul 2007	This unit had a severe case of the pitting you described, I ended up doing exactly what you mentioned during the lass rebuild session. Just discovered that my reduced clamping force is the culprit, inreased it and problem solved...knock on wood.

17th February 2009, 02:44 PM	#4
Tino_diy diyAudio Member Join Date: Feb 2009	Sorry, I have some skipping problem with my CJ DV-2b cd player, which uses a Philips L1210/11 tray loader and VAM1201 (I replaced it trying to fix the skip bits problem) and have noted that the clamp bottom base is not very flat. Maybe that also my problem is due to the clamp? Conrad Johnson DV2b skips If that can be the problem, is it possible to do what stephensank wrote also on the L1210/11 clamp? But I don't see how to unmount it... Thanks, Tino

28th February 2009, 04:52 AM	#5
lu64319 diyAudio Member Join Date: Feb 2009	I suggest you to check lubricate on tracking mortor. Sometimes when the grease less will cause skip.

2nd March 2009, 02:04 PM	#6
Tino_diy diyAudio Member Join Date: Feb 2009	Hi lu64319, I have tried many times to lubricate the different mechanics (VAM1201, VAm1202) I replaced, but that never solved the problem. This week-end I replaced all the mechanic (including the tray loader, for the first time) with a old CD12.1 and apparently there are no more skips on bought CDs, but with the CD-R burned at more than 74'. Probably the problem was on the tray loader (clamp not leveled) and I will try to add a VAM1201/J on this new L1210/11 loader... I will update my original post when I will sure of the solution. Thanks for your interest. Tino

3rd March 2009, 04:47 PM	#8
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	So you mean to leave them dry - no new lube?

4th March 2009, 06:54 AM	#9
Tino_diy diyAudio Member Join Date: Feb 2009	In past, I have found some problem with grease, but never with oil (specific for mechanical gears). In any case, also with a new mechanic not lubricated I still had skipping problems, so my real problem was the tray loader... Ciao!

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