Replacing Sony KSS-240a laser in Arcam alpha 7 CD - Page 8

JonHarrison · 15th January 2012, 12:52 PM

Quan,

How do you know that the laser assembly was faulty and is the only problem ?

I may be wrong but I believe that the laser focuses first (lens assembly moves up and down) and then once focus has been found the disc spins to read the TOC. (Some other players spin the disc first and then focus). If the disc is spinning that means that focus has been found which is a good sign. Check that the sled can track across the disc properly, it may be that it can't scan to the centre of the disc. I also assume that you have already checked the power supply voltages and ripple ?

Jon

Mooly · 15th January 2012, 05:12 PM

Not wrong at all there Jon, you're spot on, the disc doesn't spin until focus is found... and that is much easier to do on a stationery disc. The disc is then "kicked" up to approx the correct speed at which point the data coming off disc is compared to an internal crystal clock. The disc motor servo then brings the disc speed up or down until its phase locked to the oscillator.

quan · 15th January 2012, 07:19 PM

Quote:

Originally Posted by JonHarrison

Quan,

How do you know that the laser assembly was faulty and is the only problem ?

I may be wrong but I believe that the laser focuses first (lens assembly moves up and down) and then once focus has been found the disc spins to read the TOC. (Some other players spin the disc first and then focus). If the disc is spinning that means that focus has been found which is a good sign. Check that the sled can track across the disc properly, it may be that it can't scan to the centre of the disc. I also assume that you have already checked the power supply voltages and ripple ?

Jon

Yes Jon, i assumed the laser is the problem. I did moved the sledge away from center and it return to start up position when loading on disc. I have replaced the laser already but no TOC. The disc initially spin slowly ,the sledge move up and down then the disc spin faster for three seconds then stops and no disc appears. I can't find service manual for this cdp-which is a sony 291.
Quan

soliton · 21st January 2012, 08:38 AM

Hello, I have an Arcam 7SE that skips. I already have the replacement laser. Would somebody be kind enough toPM me Kora's PDF doc? Kora even?
This is the most detailed, musical player I have heard (i have limited experience) and would love to get it right again. Thanks.

Hoser1 · 8th February 2012, 10:02 PM

Can I please get the (how to replacement KSS 240A PDF) Thanks you (jose.donna@sbcglobal.net)

Hi-Q · 16th April 2012, 05:33 PM

My Arcam 7 has developed a fault. It starts to play the CD but certain frequencies have a raggedness about them, the tracks also sound slightly slower in speed but the difference is very very slight. Also, just gently tapping the top of the case causes skipping, even jumping to the next track! Is this a worn laser fault? Perhaps someone could send me the pdf about laser module replacement, it would be most appreciated. (lez@ntlworld.com)
Many thanks in advance, Les

Mooly · 16th April 2012, 06:18 PM

The CD's speed is crystal controlled so I very much doubt there is any issue there. If you want to prove it then play a test CD with tones and use a frequency counter on the audio output to check. No laser fault can alter the speed.

The KSS240 is dead easy to replace and could well be suspect although normally I like to prove optical blocks faulty first. The 240 had a problem with the lens suspension assembly I seem to remember.

gmphadte · 18th April 2012, 10:05 AM

Sony CD head repairs !!!

burmar · 17th May 2012, 12:55 PM

Please... i would like to replace kss-240a me too...
Can i have the guide on pdf ?
Thanks in advance

Quote:

gipo63@yahoo.it

15th January 2012, 05:12 PM	#72
Mooly diyAudio Member Join Date: Sep 2007	Not wrong at all there Jon, you're spot on, the disc doesn't spin until focus is found... and that is much easier to do on a stationery disc. The disc is then "kicked" up to approx the correct speed at which point the data coming off disc is compared to an internal crystal clock. The disc motor servo then brings the disc speed up or down until its phase locked to the oscillator. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

8th February 2012, 10:02 PM	#75
Hoser1 diyAudio Member Join Date: Feb 2012	Need PDF Can I please get the (how to replacement KSS 240A PDF) Thanks you (jose.donna@sbcglobal.net)

16th April 2012, 06:18 PM	#77
Mooly diyAudio Member Join Date: Sep 2007	The CD's speed is crystal controlled so I very much doubt there is any issue there. If you want to prove it then play a test CD with tones and use a frequency counter on the audio output to check. No laser fault can alter the speed. The KSS240 is dead easy to replace and could well be suspect although normally I like to prove optical blocks faulty first. The 240 had a problem with the lens suspension assembly I seem to remember. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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15th January 2012, 12:52 PM	#71
JonHarrison diyAudio Member Join Date: Mar 2004 Location: UK	Quan, How do you know that the laser assembly was faulty and is the only problem ? I may be wrong but I believe that the laser focuses first (lens assembly moves up and down) and then once focus has been found the disc spins to read the TOC. (Some other players spin the disc first and then focus). If the disc is spinning that means that focus has been found which is a good sign. Check that the sled can track across the disc properly, it may be that it can't scan to the centre of the disc. I also assume that you have already checked the power supply voltages and ripple ? Jon

21st January 2012, 08:38 AM	#74
soliton diyAudio Member Join Date: Nov 2011	Hello, I have an Arcam 7SE that skips. I already have the replacement laser. Would somebody be kind enough toPM me Kora's PDF doc? Kora even? This is the most detailed, musical player I have heard (i have limited experience) and would love to get it right again. Thanks.

16th April 2012, 05:33 PM	#76
Hi-Q diyAudio Member Join Date: Oct 2007	My Arcam 7 has developed a fault. It starts to play the CD but certain frequencies have a raggedness about them, the tracks also sound slightly slower in speed but the difference is very very slight. Also, just gently tapping the top of the case causes skipping, even jumping to the next track! Is this a worn laser fault? Perhaps someone could send me the pdf about laser module replacement, it would be most appreciated. (lez@ntlworld.com) Many thanks in advance, Les

18th April 2012, 10:05 AM	#78
gmphadte diyAudio Member Join Date: Jul 2003 Location: Dona paula, Goa	Sony CD head repairs !!!

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