Hi all,
Just bought a replacement laser unit KSS-210A. I removed the anti static solder blob and fitted it but it does not work (spindle motor does not spin). I noticed that the new laser unit has a resistor (small black one) on the circuit board above where the anti static link was... my old laser unit is missing that and looks like it was snipped off. Any ideas?
Thanks,
D.
Just bought a replacement laser unit KSS-210A. I removed the anti static solder blob and fitted it but it does not work (spindle motor does not spin). I noticed that the new laser unit has a resistor (small black one) on the circuit board above where the anti static link was... my old laser unit is missing that and looks like it was snipped off. Any ideas?
Thanks,
D.
The KSS210 is 'second sourced' from many suppliers and there are bound to be differences.
Does the new laser emit any visible light during the brief focus search operation when the lens bobs up and down.
Does the new laser emit any visible light during the brief focus search operation when the lens bobs up and down.
Hi,
It appears to emit a red light. It bobs up and down 3 times and then the process stops. No TOC is read, display shows as if no CD is inserted, and the spindle motor never starts spinning.
Thanks,
D.
It appears to emit a red light. It bobs up and down 3 times and then the process stops. No TOC is read, display shows as if no CD is inserted, and the spindle motor never starts spinning.
Thanks,
D.
That all sounds normal.
Has fitting this new laser changed the symptoms of the original fault i.e. did the player with the old laser also not attempt to spin the disc ? It will only attempt to spin when focus is found on the reflective layer of the CD. The spindle motor will never turn without a disc present.
Has fitting this new laser changed the symptoms of the original fault i.e. did the player with the old laser also not attempt to spin the disc ? It will only attempt to spin when focus is found on the reflective layer of the CD. The spindle motor will never turn without a disc present.
The old laser does work but intermittently. The new laser never works. The old laser's lens did not always bob up and down as expected, but when working the CD is read and plays ok.
Also I guess I could tweak the pot (i'm assuming this is the laser's power) on the laser unit though it looks like it's in the same position as the old one. There are also 5 pots (VR101-105) on the mainboard which I should investigate.
Correction to my original post, there is no resistor next to anti-static link, not sure what it is but my voltmeter says it has infinite resistance. Hope this test hasn't fried the laser 🙂
Also I should add the new laser is a very cheap but new one off ebay.
Also I guess I could tweak the pot (i'm assuming this is the laser's power) on the laser unit though it looks like it's in the same position as the old one. There are also 5 pots (VR101-105) on the mainboard which I should investigate.
Correction to my original post, there is no resistor next to anti-static link, not sure what it is but my voltmeter says it has infinite resistance. Hope this test hasn't fried the laser 🙂
Also I should add the new laser is a very cheap but new one off ebay.
I would refit the old laser and look for differences in the fault. I have had the motors go low resistance, the spindle motor should run easily with 1.5 volts, and I have had a couple of older motors go open circuit.
Don't twiddle without understanding what you are doing. The laser power is factory set and can not checked without a laser power meter.
This will give you a good idea of what is involved.
http://www.diyaudio.com/forums/digital-source/226288-sony-cdp790-kss240-restoration-project.html
Fitting the new part is inconclusive at the moment. It may of may not be faulty.
Perhaps I'm being naive but aren't these lasers made to strict tolerances? I would have thought it possible to swap in an exact replacement and for it to work... or is it usual to have to "tune" it with an oscilloscope to make it work?
The KSS types usually do work OK with no adjustments but note the word OK which isn't the same as optimal.
A scope should always be used. Its standard kit for any diagnostic work.
A scope should always be used. Its standard kit for any diagnostic work.
Hi again,
I've had another play with the unit after parking it for a while. I noticed with the old laser the bobbing problem (i.e. the lens does not bob up and down) has returned. Fitting the new laser also showed up bobbing issues, e.g. half bobs, but it did start bobbing correctly after a while. So does this mean it's a logic board problem at worse? And a ribbon cable problem at best? What can a novice reasonably do at this point?
Thanks for reading!
D.
I've had another play with the unit after parking it for a while. I noticed with the old laser the bobbing problem (i.e. the lens does not bob up and down) has returned. Fitting the new laser also showed up bobbing issues, e.g. half bobs, but it did start bobbing correctly after a while. So does this mean it's a logic board problem at worse? And a ribbon cable problem at best? What can a novice reasonably do at this point?
Thanks for reading!
D.
This was nearly 12 months ago 🙂
Erm... right, if the new lens has this odd 'half bob' as you call it, and the old lens did too, then that is pretty conclusive on there being an electronic issue somewhere. It doesn't really sound like a ribbon cable problem, that would be all or nothing as far as the lens focus coil was concerned.
You need to check all the basics which means checking all the supplies are correct and clean (you need a scope for that) and then looking further at things such as the amplitude of the focus drive signal.
A problem like this is moving into real fault-finding territory. You might get lucky though... check the rails first and look visually for any bulged caps in the power supply.
Erm... right, if the new lens has this odd 'half bob' as you call it, and the old lens did too, then that is pretty conclusive on there being an electronic issue somewhere. It doesn't really sound like a ribbon cable problem, that would be all or nothing as far as the lens focus coil was concerned.
You need to check all the basics which means checking all the supplies are correct and clean (you need a scope for that) and then looking further at things such as the amplitude of the focus drive signal.
A problem like this is moving into real fault-finding territory. You might get lucky though... check the rails first and look visually for any bulged caps in the power supply.
Before the lens is instructed to move up and down to find the focus distance, a signal must be sent to the servo processor to tell that the lens pickup is ALREADY at the innermost "home" position. There is a switch that is connected based on the movement of the pickup to its home position. Check this first if the focus search action is never initiated. May be there is a dirt that prevents the pickup to move to the "home" position? May be there is issue with the switch (including cabling to the servo)? Servo electronics failure should be the last issue to expect.
Assume no issue with the "at-home signal/command". Lens will move up trying to get the focus distance (sometimes this wont happen if there is no disc in place, unless the sensor is blocked to trick the servo). Once (up movement) is enough if the CD reflective surface is clean and within distance...
Without the laser being on (the visible red light), of course no focus distance can be found. Current intensity (of the laser) will also affect reading, but adjustment through the potentiometer should be the last effort.
Distance between disc and laser, if too far will make reading impossible or difficult because the lens has to move up very high. This is probably a rare issue but it happens.
Before even considering the above, it is a good practice to make sure the CD is clean and the cable is not faulty, especially the flexible that can easily cracked and disconnected without visual sign, especially inside the slot. You should probably purchase new ones?
BTW, it is not the case with your issue, but sometimes the lens movement is not normal because there is metallic dirt. The movement is based on magnetic field created by two small magnets that sometimes attract small metals. (My be rare but happens too)
Now, assuming that the FOCUS distance can be read, signal is sent to the servo to tell the current situation and for the servo controller to turn the spindle (and sled) motor. Does the CD spin at all?
If it spins, the speed should be suitable. Check if the spindle motor get sufficient voltage. Servo electronics failure to red the signal should be the last problem to be expected.
If it spins, the speed should be suitable. Check if the spindle motor get sufficient voltage. Servo electronics failure to red the signal should be the last problem to be expected.
You are talking China or Korea!
First quality parts go to OEM manufacturers.
Second quality sold out of side door!
Poor quality sold to on line sellers!
Rejects still get to on line sellers.
You can be buying brand new, reject or fake parts.
Even the U.S.A. military have been caught out. 😱
Thanks everyone. I refitted old laser and it bobbed ok. I wiggled all the wires as it bobbed and no probs. CD played for 1 min and then stopped. Laser no longer bobs!
Is it worth getting this repaired and how much? Any well-known and trusted repairers you can recommend in the UK? Otherwise I guess it's sell as spares as I don't have the skills to "go circuit board".
D.
Is it worth getting this repaired and how much? Any well-known and trusted repairers you can recommend in the UK? Otherwise I guess it's sell as spares as I don't have the skills to "go circuit board".
D.
I wouldn't know who to recommend tbh. You could well end up paying more than the unit is worth.
It sounds like the unit needs a thorough investigation however it would still be worthwhile just removing the main PCB and checking for dries on the regulators and also looking at the reservoir caps.
It sounds like the unit needs a thorough investigation however it would still be worthwhile just removing the main PCB and checking for dries on the regulators and also looking at the reservoir caps.
I took the pcb up and noticed a dark burnt area. I resolder the dry joints but no joy. The component is a black squarish item (6x4x2mm) with 3 legs marked D1858RG. It's pcb part id is Q102 if this helps. There are 6 of these in a row. It seems involved with the FOD signal... which is the focus signal perhaps?