lm 317t voltage reg

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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.
 
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.
 
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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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.:confused::confused::confused:

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 :)
 
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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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.
 
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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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 :)
 
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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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.
 
Thanks 'Mooly' - I have taken the effort in taking some clear close-up pictures of me going as far as I dare with cleaning the lens - is there anything you can point out in any of those pictures which might be relevant to me Camera+ photo ? Sorry, this will literally be my first time with a soldering iron! If you search for Arcam CD73 laser on eBay you will see the part that I have purchased. I guess I don't want to have to remove my existing laser when there maybe nothing wrong with it after doing some voltage tests.
 
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Voltage tests aren't conclusive proof (as you can see reading this thread) but they can useful if they do show a problem. If they don't then the pickup is still a suspect.

I always remove the drawer for access on players like these. Shpuld be fairly obvious when you look at it as to how it comes out. Open it first under power as far as it goes and then disconnect the mains. Often just a bendy plastic tab somewhere is a stop either on the drawer or the frame.

In the last few pics you can see the white plastic housings at each end of the rail. The rear one has a bendy plastic tab that "holds" the rail in place horizontally. Push the rail hard into the tab and then bend the tab out of the way. The rail slides out completely allowing the pickup to be removed. Refit is just the reverse. Theres no timing of gears to worry about and the pickup will automatically go to the correct position at power up.

The ribbon cable is just a push fit (I can't see any locking tabs on the socket on the pickup). Hold it by the blue part which is far stronger when pushing it back.

The shorting link if it has one is just a solder blob across two of the lines of print on the pickup. This is a different pickup but you get the idea. Just quickly touch a clean iron tip on the solder and it will come off.
 

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Voltage tests aren't conclusive proof (as you can see reading this thread) but they can useful if they do show a problem. If they don't then the pickup is still a suspect.

I always remove the drawer for access on players like these. Shpuld be fairly obvious when you look at it as to how it comes out. Open it first under power as far as it goes and then disconnect the mains. Often just a bendy plastic tab somewhere is a stop either on the drawer or the frame.

In the last few pics you can see the white plastic housings at each end of the rail. The rear one has a bendy plastic tab that "holds" the rail in place horizontally. Push the rail hard into the tab and then bend the tab out of the way. The rail slides out completely allowing the pickup to be removed. Refit is just the reverse. Theres no timing of gears to worry about and the pickup will automatically go to the correct position at power up.

The ribbon cable is just a push fit (I can't see any locking tabs on the socket on the pickup). Hold it by the blue part which is far stronger when pushing it back.

The shorting link if it has one is just a solder blob across two of the lines of print on the pickup. This is a different pickup but you get the idea. Just quickly touch a clean iron tip on the solder and it will come off.

Thanks - I'll give that a go - no point in paying Arcam £160 because I may as well just put that towards a new player (however I do like the sound of this particular Arcam).

Someone at work gave me a tip - they said check to see if there is a laser coming from the lens by holding a digital camera over the top and looking in the preview screen of the camera because many digital cameras can 'see' infra-red (obviously check to see if your camera can first by testing on a household remote control).

Also, turn the wick up on the lens a very small amount clockwise using the turn screw as seen on the very bottom photo to see if this supplies more power to the laser from which it may start to engage with the CD.

Are the above useful tips for diagnosing laser problems do you think?

Also - if I need to de-solder the shorting link - does that mean I need to solder it back on again with the new lens?
 
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The shorting link is just to protect the laser diode from static during handling. Officially it is removed after connecting the ribbon. The only time the link is in place is when handling and storing the pickup.

That "turn screw" is a preset resistor. General advice is don't touch unless you know what you are doing and can see and measure the effect. The serial number on your laser ends in 411. That means the current should be 41.1 milliamps. That current determines the optical power output of the laser diode. By all means check it by deducing the current from the volt drop across the low value resistor that will be present in the APC (automatic power control circuit) part of the circuitry as detailed earlier in the thread.

A digital camera may well show the laser light in the same way that it shows an ordinary IR remote control is transmitting but it will say nothing of the output power.

Fit the new pickup... and if it doesn't work then think about diving in deeper :)
 
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