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

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Hi there, my first post! Nice forum!
I'm having problems with my cd player which has a KSS240A pickup so I ordered a replacement part and already arrived.
Please Kora will you send me your famous PDF? I do really want this player to work! Had it for almost 12 years and want it back in top shape, it is a cheap Onkyo 7210 but worked really nice!
labloos@gmail.com
Thanks in advance!
 
My friend has an Arcam Alpha 7 and 9 cd players both skip tracks is the Sony kss 240 the replacement laser mechanism for these models and if they are could someone forward the pdf file mentioned in this thread.
I have been looking for a replacement for him for about 3 years. Thanks in advance
 
Hi guys, i just replaced optical block on sony 291- Kss 240 A. It is spinning and the optical move up and down but still read no disc?. Any advice re trouble shooting?
Quan.
PS-also how do i remove the screws that hold the motor in place to replace the caps on rf board?
 
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If any presets have been disturbed (and I'm not familiar with your player by model number alone) then you may have problems getting it working. Nothing on the pickup should be touched.

All mechanical issues must be attended too first. The sled must be free and smooth. It must return correctly to the rest position when powered up. The platter height must be correct and the platter running true. The spindle motor may be faulty/worn. Worth isolating it electrically and zapping it across a 9 volt battery for a few seconds to clean the commutator.

The fact it spins (the platter should not normally spin with NO disc inserted) means that focus has been found.

From thereon in you need a scope to look at the RF signal to determine where problems lie.

All rails should be clean and correct (scope them).
Any PLL oscillator that is adjutable must be set as per the manual.

From memory motors are usually desoldered from the PCB to remove.
 
If any presets have been disturbed (and I'm not familiar with your player by model number alone) then you may have problems getting it working. Nothing on the pickup should be touched.

All mechanical issues must be attended too first. The sled must be free and smooth. It must return correctly to the rest position when powered up. The platter height must be correct and the platter running true. The spindle motor may be faulty/worn. Worth isolating it electrically and zapping it across a 9 volt battery for a few seconds to clean the commutator.

The fact it spins (the platter should not normally spin with NO disc inserted) means that focus has been found.

From thereon in you need a scope to look at the RF signal to determine where problems lie.

All rails should be clean and correct (scope them).
Any PLL oscillator that is adjutable must be set as per the manual.

From memory motors are usually desoldered from the PCB to remove.
Thanks, i did desoldered the motor and replace the caps on the board just for measures. No settings has been touched. When the disc is loaded the laser move up and down , motor spins but after a few seconds it reads NO DISC. I have no scope to check where the problem lies. Is there anything i can do with just a simple multimeter?
Quan
 
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You are very limited without a scope unfortunately.

Is the sled definitely OK. If you move it away from the centre and then power up does it return to the correct inner rest position.

If that's OK then I think you have problems using just a multimeter. You need to see what the pickup is seeing off the disc, amplitude and so on. Just guessing otherwise.
 
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
 
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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,

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
 
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.
 
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
 
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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.
 
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