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Old 10th November 2012, 10:11 PM   #21
dacen is offline dacen  Norway
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The microswitches are probably those telling the microprocessor that the tray is in the out position, and the other switch telling that the tray is fully seated inside the player. I would not suspect those as the player is running the laser trying to focus on the surface of the CD. If the tray switch for seated fully inside the player had been faulty this action would not have taken place. This is just my guess.
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Old 10th November 2012, 10:20 PM   #22
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Did you remove the solder short on the new laser?

The manual is very clear on how to check the laser current. It is preset and the value for your particular example should be printed on it. The manual shows how to check the value is correct.

On the original red herring, I note that the 3.6V regulator was changed by Arcam to a low drop-out type, according to the manual.
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Old 10th November 2012, 11:35 PM   #23
dacen is offline dacen  Norway
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On page 9 in the schematic diagram you will find IC U101, CXA2581. Pin 1 is in control of the voltage to the LD (laserdiode) through transistor Q101 giving out a constant current. Pin 2 is the feedback from the photo detector. An idea would be to see if the voltage is coming through this transistor and all the way to pin 10 on connector M102. This output is the so called APC (automatic power control) This arrangement is to keep the power inside the envelope at different temperatures and taking care of the aging of the laser. See page 2 and 10 on the PDF.
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Last edited by dacen; 10th November 2012 at 11:42 PM.
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Old 11th November 2012, 06:42 AM   #24
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by Edwar65 View Post
hi, U502 readings were: 10.80/5v respectively.
Still showing no disc error on display, even with disc in,everything operates as normal and yes, laser does move up/down approx 3 times,also moves to rest position if moved before power up, only thing I can't see is any light from laser?
Can I assume been sent a duff replacement laser from ebay seller,as with the replacement in, it was making weird high pitched noises on power up and there was no rotation of cd with replacement in situ,I am now running on original unit(which may also be duff)?
I have now located a seller selling(reportedly) genuine stamped sony lasers not unbranded item that I have in my possession,do you think it would be worth trying a new sony laser?
The workhop manual suggests looking at microswitches, although I can't see anything like this near mechanism?
many thanks,
tom.
Next step as the others mention is to check the laser diode is drawing current.
Read page 3 and 4 of the manual where it starts with fig 2 "Laser diode direct monitor points". Page 9 top left is R101. You are measuring the voltage across this resistor. What the manual doesn't say is that for a non working player this voltage will only be present during the brief focus search operation when the lens is bobbing up and down. So to be sure you will have to keep opening/closing the tray to keep activating the focus search routine.

See what voltage you get and how it compares to the serial number on the pickup
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Old 13th November 2012, 09:41 PM   #25
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hi, what sort of voltage reading should I be getting from transistor thru to pin 10 of m102,i'm reading a fig. of approx -10v,can this be measured via the inductor? l102 as its difficult to get at transistor legs? I have also checked laser current via r101 and am getting 40.8mv,laser stamped up 42.8? Is this within acceptable limits?
thanks chaps,
tom.
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Old 14th November 2012, 07:13 AM   #26
Mooly is offline Mooly  United Kingdom
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The "definitive" reading is the voltage across R101 and I would just re-confirm that is still OK. 40.8 mv sounds just fine for a 42.8 reference value. It's proof enough because the laser diode itself also has a photodiode on the same die within the LD package to monitor how "bright" the LD is and this photodiode is the means by which the current is regulated. If the LD is emitting to much light the photo diode generates more voltage that is used to "turn down" the current and vice versa. The LD is extremely temperature sensitive in regard to light emission vs temperature vs current and is why the current (or more correctly light output) has to be tightly controlled. So the fact the reading is correct can be taken as proof that the emission of the laser is OK.

The -10 volts you are seeing... my guess is that you are measuring here after the focus search operation has finished and your DVM is just picking up "noise" from what is then essentially an "open circuit" condition on the collector of the transistor.

The reason I say re-measure the volt drop across the resistor is because laser diodes are very static sensitive so lets just recheck all is OK. Normally we never measure on the laser diode side of the circuitry for this very reason. I'm sure it will be OK but just make sure

So after all that you still have a non functioning player. Without use of a scope and much more detailed tests it all gets more difficult now.

Edit....
All that said, it doesn't mean the pickup as a whole is guaranteed good. If there were a problem with the internal optics etc then obviously it won't work... so at this stage we perhaps can't rule that out.
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Old 27th November 2012, 09:37 PM   #27
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Hi all, especially mooly. Well after much testing,decided to try and locate an original sony stamped laser from a well known auction site,this was installed and............Bingo,the player is fine, my first laser was duff, although that vendor won't have any returns on it, reckons it was my incompetence. I have run the player for a couple of hours and it seems fine, Id like to thank everyone for the time they spent on sending info and helpful tips,especially mooly who has been most helpful.
Just got to get rid of the low level hum from the input trannys on my music angel el34 valve amps, any suggestions???
thanks again,
tom.
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Old 28th November 2012, 06:35 AM   #28
Mooly is offline Mooly  United Kingdom
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Hi Tom, thats great news. It does sound like something was amiss internally in the pickup optics then... great result.

Hum can be difficult to clear up sometimes as there can be many causes from simple external ground loops to internal grounding problems with the wiring layout and everything inbetween. It needs a methodical approach observing and measuring exactly what is happening. I'd perhaps suggest posting a thread in the "tubes" forum.

Great result on the player
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Old 21st January 2013, 12:12 PM   #29
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Quote:
Originally Posted by Edwar65 View Post
hi, what sort of voltage reading should I be getting from transistor thru to pin 10 of m102,i'm reading a fig. of approx -10v,can this be measured via the inductor? l102 as its difficult to get at transistor legs? I have also checked laser current via r101 and am getting 40.8mv,laser stamped up 42.8? Is this within acceptable limits?
thanks chaps,
tom.
I too have 'exactly' the same problem with my Arcam CD73 - laser bobs up and down - no disc error - and I too have purchased a "so called" Arcam CD73 laser which I have not fitted yet (I thought it was plug and play). Are you able to give me your experienced guidance on how to 1. first establish that the laser is really at fault (Arcam say it could also be the display board)? and 2. how to carefully fit the laser mech. because I am not handy with a soldering iron? Thank you very much!
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Old 21st January 2013, 04:38 PM   #30
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by bitsandbobs View Post
I too have 'exactly' the same problem with my Arcam CD73 - laser bobs up and down - no disc error - and I too have purchased a "so called" Arcam CD73 laser which I have not fitted yet (I thought it was plug and play). Are you able to give me your experienced guidance on how to 1. first establish that the laser is really at fault (Arcam say it could also be the display board)? and 2. how to carefully fit the laser mech. because I am not handy with a soldering iron? Thank you very much!
I think we covered checking the basics in this thread. If its drawing the correct current then next step has to be to try the new pickup. The only soldering is the removal of the shorting link on the pickup Removal of the pickup will be straightforward mechanical dissasembly. Normally two minutes of a job. I would need one in front of me to detail it step by step but you normally just remove the disc clamp (two screws ?) and release the plastic tab on the chromed rail the pickup runs on and then slide the rail out.
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