New member and first post is looking for help, sorry
I decided to try and use my Alpha 8 CD player yesterday, after quite some time. Last time I tried to use it, it seemed to take some time to recognise discs and the it would frequently skip portions of various CD's, so I left it alone.
Today I decided to investigate so removed the top cover to observe what happens when a disc is inserted. It goes through the following process
Drawer closes
Transport moves up
Laser moves to centre of disc
There is a repeated whirring / slowdown sound which changes with the speed of the disc. The disc does not get up to full speed
I have not been able to observe the ( red ? ) laser
I have played about with x-box transports and tweaked laser output in the past, have access to a multimeter, have done component level soldering including IC (but not GBA), have no scope and a basic / rudimentary understanding of how the electronics work.
It seems to me that the laser mechanism may need replacing, but rather than go out and just buy one, it would be great if you could confirm my diagnosis, offer suggestions for other checks to perform and warn me of any installation / alignment issues I may have to face.
The player is fully dismantled and I did find one small piece of white plastic loose upon dissassembly. I have not yet identified exactly where it has come from but there are a number of similar pieces elsewhere on the transport. In the picture below it is placed on the black part of the transport Is this important or not ?
I decided to try and use my Alpha 8 CD player yesterday, after quite some time. Last time I tried to use it, it seemed to take some time to recognise discs and the it would frequently skip portions of various CD's, so I left it alone.
Today I decided to investigate so removed the top cover to observe what happens when a disc is inserted. It goes through the following process
Drawer closes
Transport moves up
Laser moves to centre of disc
There is a repeated whirring / slowdown sound which changes with the speed of the disc. The disc does not get up to full speed
I have not been able to observe the ( red ? ) laser
I have played about with x-box transports and tweaked laser output in the past, have access to a multimeter, have done component level soldering including IC (but not GBA), have no scope and a basic / rudimentary understanding of how the electronics work.
It seems to me that the laser mechanism may need replacing, but rather than go out and just buy one, it would be great if you could confirm my diagnosis, offer suggestions for other checks to perform and warn me of any installation / alignment issues I may have to face.
The player is fully dismantled and I did find one small piece of white plastic loose upon dissassembly. I have not yet identified exactly where it has come from but there are a number of similar pieces elsewhere on the transport. In the picture below it is placed on the black part of the transport Is this important or not ?
Thanks for the thoughts. I'm pretty sure the lens is clean as I have a large bottle of IPA but I will recheck that.
This one has already had some of the caps replaced as I had a hum/buzzing sound about 5 years ago. The caps that had failed were located under the DAC if I recall quickly.
Is it possible to test the voltage that feeds the laser ?
This one has already had some of the caps replaced as I had a hum/buzzing sound about 5 years ago. The caps that had failed were located under the DAC if I recall quickly.
Is it possible to test the voltage that feeds the laser ?
The laser will be fed from the 5 volt supply and a scope is always the best check because it shows noise and ripple as well as the voltage. A meter may well show a correct 5 volts even in the presence of ripple.
Measuring the voltage to the laser wont reveal much (unless there is a gross problem) because the laser is current fed and incredibly tightly controlled with an optical feedback loop within the pickup itself.
You need to confirm all the rails in the player are good. A meter will show obvious issues but if non are found then without a scope check it still doesn't mean they are actually OK.
The fact its had cap issues would be a good reason to suspect there could be similar issues now or a missed cap from earlier.
Measuring the voltage to the laser wont reveal much (unless there is a gross problem) because the laser is current fed and incredibly tightly controlled with an optical feedback loop within the pickup itself.
You need to confirm all the rails in the player are good. A meter will show obvious issues but if non are found then without a scope check it still doesn't mean they are actually OK.
The fact its had cap issues would be a good reason to suspect there could be similar issues now or a missed cap from earlier.
I would leave it powered on overnight and see what happens in the morning. You mention that you haven't used it for some time and current flow may help restore some faulty contact, cold solder joint or condition a faulty capacitor. If you get it up and running, that means the laser pickup and transport are OK but the player requires some overhauling.
I have been able to spend a little time on the player today.
After spending a little time studying the service manual to locate test points I decided to reassemble the player and see if it worked after cleaning the lens.
It did, well sort of
Although the CD hasn't been played for sometime I wouldn't say that the electronics were generally cool because it resides just above my amp, which might be a problem (and am now going to get some sorbothane feet to act as spacers to increase airflow). Nonetheless it is always possible that the process of re-connecting the cables may also have restored an oxidised contact.
Should my next steps be to complete the work on ascertaining / checking the test points for the different supplies with my multimeter, or does the additional information above point in a different direction ?
Many thanks for all the help so far.
After spending a little time studying the service manual to locate test points I decided to reassemble the player and see if it worked after cleaning the lens.
It did, well sort of
- The first CD played fine (and sounded great)
- The second CD played fine, then it skipped on track 6. I cleaned the CD and it played without issue
- I then put a new CD is (Xmas present). It struggled to recognise the CD, did the laser focussing many times and when it did eventually play it skipped tracks.
- I put the CD into a DVD player and it played fine, so it doesn't appear to be a faulty CD
- After a couple of hours I removed the CD from the DVD player and put it in the Arcam which recognised and played it fine.
Although the CD hasn't been played for sometime I wouldn't say that the electronics were generally cool because it resides just above my amp, which might be a problem (and am now going to get some sorbothane feet to act as spacers to increase airflow). Nonetheless it is always possible that the process of re-connecting the cables may also have restored an oxidised contact.
Should my next steps be to complete the work on ascertaining / checking the test points for the different supplies with my multimeter, or does the additional information above point in a different direction ?
Many thanks for all the help so far.
The laser light is near infra red which is why it looks feeble... it is our eyes that can't see it properly.
Most likely issues are caps... I can't specifically say which they would be, just that Arcam products have a certain reputation... and perhaps poor joints but they would typically be around regulators and other "non standard" parts.
You really do need to use an oscilloscope on this... that is the correct diagnostic tool. We are just making educated guesses at the moment.
Most likely issues are caps... I can't specifically say which they would be, just that Arcam products have a certain reputation... and perhaps poor joints but they would typically be around regulators and other "non standard" parts.
You really do need to use an oscilloscope on this... that is the correct diagnostic tool. We are just making educated guesses at the moment.
Re-awakening this as I now have some time again to try and fix it again. The symptoms now are that the CD tray would close but the spindle motor would not spin and there was no reading of the TOC.
I stripped the transport unit down last night to get access to the motors and switches.
Using some AAA batteries I powered the sled motor and the spindle motor.. Both worked, the spindle motor was a little hesitant to start, but that was quite possibly the contact from the wires onto the connections.
I also tested the two micro switches, they tested OK.
I partly reassembled the player, applied power and on the second / third attempt the spindle motor engaged but stalled. I gave the CD a little encouragement and it spun up and played a CD. Apparently good news. It then consistently made the high pitched "chirruping" as it read the CD TOC
Today I stripped down and reassembled the player again (not the transport) and have tested it again. It is now back to not spinning the disc.
Can anyone point me more precisely in the area I need to be looking at. I can't see a way to test the operation of the micros switches when the CD is loaded...... unless anyone knows better.
Thanks in advance for any help
I stripped the transport unit down last night to get access to the motors and switches.
Using some AAA batteries I powered the sled motor and the spindle motor.. Both worked, the spindle motor was a little hesitant to start, but that was quite possibly the contact from the wires onto the connections.
I also tested the two micro switches, they tested OK.
I partly reassembled the player, applied power and on the second / third attempt the spindle motor engaged but stalled. I gave the CD a little encouragement and it spun up and played a CD. Apparently good news. It then consistently made the high pitched "chirruping" as it read the CD TOC
Today I stripped down and reassembled the player again (not the transport) and have tested it again. It is now back to not spinning the disc.
Can anyone point me more precisely in the area I need to be looking at. I can't see a way to test the operation of the micros switches when the CD is loaded...... unless anyone knows better.
Thanks in advance for any help
The same advice still holds... you need to be using an oscilloscope to see what is going on.
The spindle motor will not spin until after focus is found on the stationary disc.
You mention it will intermittently play. This is where you need to look at the signal from the pickup to confirm the amplitude and overall Q (or quality) factor is good.
And again, supplies all have to be checked for correct voltage and the absence of ripple.
The spindle motor will not spin until after focus is found on the stationary disc.
You mention it will intermittently play. This is where you need to look at the signal from the pickup to confirm the amplitude and overall Q (or quality) factor is good.
And again, supplies all have to be checked for correct voltage and the absence of ripple.
Thanks Mooley,
The problem isn't intermittent anymore, which is generally better for diagnosis. It didn't work at all, I stripped the transport, partly reassembled and it did play again without skipping. Did a final reassembly and it didn't work again.
I was hoping when I posted that the lack of spinning the spindle would help point in a specific direction. I'm usually pretty good at diagnosing / repairing things, but on this occasion it looks like I'm a bit short of equipment....namely access to an oscilloscope...... and even if I did then the knowledge to know how to use it properly.
I doubt it is work buying a s/h one for this job, so can anyone recommend someone who could carry out a proper diagnosis & repair ? (I'm located in North Yorkshire in case there is someone local)
The problem isn't intermittent anymore, which is generally better for diagnosis. It didn't work at all, I stripped the transport, partly reassembled and it did play again without skipping. Did a final reassembly and it didn't work again.
I was hoping when I posted that the lack of spinning the spindle would help point in a specific direction. I'm usually pretty good at diagnosing / repairing things, but on this occasion it looks like I'm a bit short of equipment....namely access to an oscilloscope...... and even if I did then the knowledge to know how to use it properly.
I doubt it is work buying a s/h one for this job, so can anyone recommend someone who could carry out a proper diagnosis & repair ? (I'm located in North Yorkshire in case there is someone local)
It sounds as though it might be something physical if it works correctly when partly stripped down. That sort of changes things a little if it did work reliably every time in that state. Have you looked carefully at all the connections to and from the pickup such as any ribbon cables and so on.
(I'm afraid I don't know anyone who would do repairs on these
)
(I'm afraid I don't know anyone who would do repairs on these
)Thanks.
I'm going to do another strip down and rebuild over the next few days - getting quicker at this all the time.
I have done some more checking, the sled moves to the centre of the disc, the laser is illuminating, it rises (to focus ?) twice before going back to rest and switching off. I assume that's probably because it hasn't focussed and found a disc to feel the need to power the spindle motor....then again it could be something else.
Having had a close examination of the transport and a read around I found a great thread describing a repair on a Sony CDP-790 with the same KSS-240A laser ...... no doubt you remember doing that one.
Sony CDP790 and KSS240 Restoration Project
I'm going to do another strip down and rebuild over the next few days - getting quicker at this all the time.
I have done some more checking, the sled moves to the centre of the disc, the laser is illuminating, it rises (to focus ?) twice before going back to rest and switching off. I assume that's probably because it hasn't focussed and found a disc to feel the need to power the spindle motor....then again it could be something else.
Having had a close examination of the transport and a read around I found a great thread describing a repair on a Sony CDP-790 with the same KSS-240A laser ...... no doubt you remember doing that one.
Sony CDP790 and KSS240 Restoration Project
Just an update on this:
I found someone locally who had the equipment, skills & knowledge to do a component level diagnosis. Top bloke, diagnosed that the problem was a resistor and a transistor on the D/A board.
The player is back and working
Not quite DiyAudio in this case, but I had at least done some valid diagnosis along the way. Thanks for the help and interest along the way
I found someone locally who had the equipment, skills & knowledge to do a component level diagnosis. Top bloke, diagnosed that the problem was a resistor and a transistor on the D/A board.
The player is back and working
Not quite DiyAudio in this case, but I had at least done some valid diagnosis along the way. Thanks for the help and interest along the way
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