Stripdown/Clean of CDM12.4 - Page 2

tiefbassuebertr · 02:04 PM

Replacing Sharp's hologram laser diode (laser tube) LT0H30A /P/J (LTOH30A_P, LTOH30A_J, LT0H30A_P, LT0H30A_J) in the laser head of Philips VAM1201
(emergency repair - P / J type = sealed / semi-circular seal)

go to
¹ãÖÝÊÐ¸ñÈÕµÃ¾«ÃÜµç×ÓÓÐÏÞ¹«Ë¾ (thread from China)

unfortunately the offered translation in english don't goes open (to much losses by automaticlly google translation). But some interesing things you will find, e. g. method of visual power out check for laser light. Because in some cases such websites don't goes open after certainly time, I have save the description and pics by the attached files.

retube · 13th September 2010, 05:12 PM

hello everybody,

hope i'm in the right place with my question:

since i'm a newbee in this are i wonder, if i could replace a vam 1202/12 with a vam 1204 ???

The two visible diffents are a) there is a chip on the backside and b) the capbles are already fixed to the laserunit.

Mooly · 05:58 PM

They are different. The chip is the RF amplifier which is mounted on the pickup for better performance. The other just has the laser power circuit (discrete components) with the RF amplifier being on the main PCB.

Edit... the 1202/12 should be available,
http://www.chsinteractive.co.uk/sear...?query=vam1202

tiefbassuebertr · 21st September 2010, 07:01 PM

any news for the reason to use this two different hologram diode outlines and the currently manufacturers (have a look to post #10) ?

phi70 · 25th September 2010, 08:17 AM

Any chance I can replace a CDM12.4/05 with w a VAM1204 with no hacks?
been fed up with having to constantly replace SF-CD1 CD12.4's and so far only 50% of the so called new heads would work and they only work for a few months.
Is there any adjustments required (seems to be an adj pot right behind the head)
or is the rumor that the servo will adjust itself is true?

zeonrider · 25th September 2010, 09:41 AM

Nice work, but why new cost around 12 E!?

Regards zeoN_Rider

Mooly · 25th September 2010, 11:05 AM

Quote:

Originally Posted by phi70

Any chance I can replace a CDM12.4/05 with w a VAM1204 with no hacks?
been fed up with having to constantly replace SF-CD1 CD12.4's and so far only 50% of the so called new heads would work and they only work for a few months.
Is there any adjustments required (seems to be an adj pot right behind the head)
or is the rumor that the servo will adjust itself is true?

As far as I know they are interchangeable.
The so called new CDM12.4's I have seen and used have been terrible, just as you describe. The usual suppliers I deal with... dedicated brown goods spares wholesalers... never list the VAM1204.

The pot on the pickup is factory adjusted (laser power) and should not be touched. All the players I have seen that use the 12.4 have had no servo adjustments possible.

tiefbassuebertr · 25th September 2010, 04:29 PM

As I know, the abbreviation "CDM" means compact disc mechanism (only for CD's with PCM according Reed Book standart) and the abbreviation "VAM" means Video-Audio mechanism (also for CDRW and video CD's.
By the last CD-Player series - e. g. CD753 about
PhilipsCD753
in the first series was a CDM12.1 in use and in the later series the VAM1201 for reading CDRW.
But I don't know exactly, whether the VAM1204 was also the successor of CDM12.4 in the same kind.
Commercial Philips products with CDM12.4 was only one model of the the CDR series (recorder & player mechanism in the same housing - the CDM12.4 was in use by the player part) so as various personal computer cd rom devices.
I don't know any products from Philips, where is an VAM1204 in use.

phi70 · 27th September 2010, 01:04 AM

Over the past several years I have collected 2 SF-CD1s and went through numerous laser heads.

Whenever they act up, one will not read anything (NO DISC)
and the other one reads intermittently and absolutely will not read any copied CD-Rs.

A unit with a newly replaced laser will not survive a short road trip to a friend's house... NO DISC upon arrival and it happens everytime.

Yes. It's just Philips CDM12.4, you can find them everywhere on EBay but most of them are "cannibalized parts" sold as new.

The CD1s seem to "chew through laser heads one every few months so I thought. Lately it got so bad I thought its more likely the board underneath the transport that is getting too old to read anything.

Spent the weekend trying to fix my them and after fiddling with just about everything it turns out the lasers are still fine. The heads need manual adj despite all the docs floating around stating otherwise.

Tweaked the alignment of the heads with a torx screwdriver using purely trial and error gets rid of the "no disc" error and the "skipping track" and "not able to read copied CDs" problem.

The SF-CD1, unlike Levinson and Wadia, does not have a locking screw to secure the head.

The damn silicon stud mounts with much tolerance arent helping. They give way during transportation and causing the heads to be misaligned.

phi70 · 27th September 2010, 02:35 AM

BTW thanks to Mooly's post about the laser power trim pot. I read it too late.
Killed one of the replacement heads. But the 2 torx screws definitely need adjustment.

I was able to get on SFCD1 which shows No Disc with a supposedly 2 month new laser to read reliably, and my other one which never reads CDRs to read after tweaking the torx screws that adjusts the distance and angle of the head to media. Lot of patience required though.

13th September 2010, 05:55 PM	#13
Mooly diyAudio Moderator Join Date: Sep 2007	They are different. The chip is the RF amplifier which is mounted on the pickup for better performance. The other just has the laser power circuit (discrete components) with the RF amplifier being on the main PCB. Edit... the 1202/12 should be available, http://www.chsinteractive.co.uk/sear...?query=vam1202 __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.* Last edited by Mooly; 13th September 2010 at 05:58 PM.

25th September 2010, 09:41 AM	#16
zeonrider diyAudio Member Join Date: Mar 2004 Location: Belgrade RS	? Nice work, but why new cost around 12 E!? Regards zeoN_Rider

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13th September 2010, 05:12 PM	#12
retube diyAudio Member Join Date: Sep 2009 Location: Berlin	hello everybody, hope i'm in the right place with my question: since i'm a newbee in this are i wonder, if i could replace a vam 1202/12 with a vam 1204 ??? The two visible diffents are a) there is a chip on the backside and b) the capbles are already fixed to the laserunit.

21st September 2010, 07:01 PM	#14
tiefbassuebertr diyAudio Member Join Date: Jul 2005 Location: D-55629 Schwarzerden	any news for the reason to use this two different hologram diode outlines and the currently manufacturers (have a look to post #10) ?

25th September 2010, 08:17 AM	#15
phi70 diyAudio Member Join Date: Oct 2006	Any chance I can replace a CDM12.4/05 with w a VAM1204 with no hacks? been fed up with having to constantly replace SF-CD1 CD12.4's and so far only 50% of the so called new heads would work and they only work for a few months. Is there any adjustments required (seems to be an adj pot right behind the head) or is the rumor that the servo will adjust itself is true?

25th September 2010, 04:29 PM	#18
tiefbassuebertr diyAudio Member Join Date: Jul 2005 Location: D-55629 Schwarzerden	As I know, the abbreviation "CDM" means compact disc mechanism (only for CD's with PCM according Reed Book standart) and the abbreviation "VAM" means Video-Audio mechanism (also for CDRW and video CD's. By the last CD-Player series - e. g. CD753 about PhilipsCD753 in the first series was a CDM12.1 in use and in the later series the VAM1201 for reading CDRW. But I don't know exactly, whether the VAM1204 was also the successor of CDM12.4 in the same kind. Commercial Philips products with CDM12.4 was only one model of the the CDR series (recorder & player mechanism in the same housing - the CDM12.4 was in use by the player part) so as various personal computer cd rom devices. I don't know any products from Philips, where is an VAM1204 in use.

27th September 2010, 01:04 AM	#19
phi70 diyAudio Member Join Date: Oct 2006	Over the past several years I have collected 2 SF-CD1s and went through numerous laser heads. Whenever they act up, one will not read anything (NO DISC) and the other one reads intermittently and absolutely will not read any copied CD-Rs. A unit with a newly replaced laser will not survive a short road trip to a friend's house... NO DISC upon arrival and it happens everytime. Yes. It's just Philips CDM12.4, you can find them everywhere on EBay but most of them are "cannibalized parts" sold as new. The CD1s seem to "chew through laser heads one every few months so I thought. Lately it got so bad I thought its more likely the board underneath the transport that is getting too old to read anything. Spent the weekend trying to fix my them and after fiddling with just about everything it turns out the lasers are still fine. The heads need manual adj despite all the docs floating around stating otherwise. Tweaked the alignment of the heads with a torx screwdriver using purely trial and error gets rid of the "no disc" error and the "skipping track" and "not able to read copied CDs" problem. The SF-CD1, unlike Levinson and Wadia, does not have a locking screw to secure the head. The damn silicon stud mounts with much tolerance arent helping. They give way during transportation and causing the heads to be misaligned.

27th September 2010, 02:35 AM	#20
phi70 diyAudio Member Join Date: Oct 2006	BTW thanks to Mooly's post about the laser power trim pot. I read it too late. Killed one of the replacement heads. But the 2 torx screws definitely need adjustment. I was able to get on SFCD1 which shows No Disc with a supposedly 2 month new laser to read reliably, and my other one which never reads CDRs to read after tweaking the torx screws that adjusts the distance and angle of the head to media. Lot of patience required though.