I have an Atoll 80 CD Player that I picked up for pretty cheap at a second-hand place. It looks like it was built in the early 00's (a date stamp of 2004 on the cd tray is the latest date I could see). Unfortunately it seems something is wrong with the transport side of things -- on a music CD, there is a fair amount of distortion, especially when higher-frequency notes are played or sung.
I burned a CD with some test tones and disconnected the audio output from the player's internal pre-amplifier. I played a 1kHz sine tone on the test CD and it came out looking quite distorted. (A 1 kHz tone through the preamp stage was very clean, so I have eliminated this part).
When progressively higher frequency tones are played (5 kHz and 10kHz) from the CD, my oscilloscope is showing alternating periods of high amplitude and low amplitude. As far as I can tell, this is not present in the lower frequencies.
However, I'm now stuck on where to go from here. I would like to try and DIY this repair, mostly for the experience, but I could use a few pointers on where to look next.
I've attached a photo of the circuit board for the transport. It seems that most of the decoding logic is done here -- I can't see any DAC chips on the main board. I know that the one chip I can read is the transport controller, but what are the other two?
Thanks in advance for any help!
I burned a CD with some test tones and disconnected the audio output from the player's internal pre-amplifier. I played a 1kHz sine tone on the test CD and it came out looking quite distorted. (A 1 kHz tone through the preamp stage was very clean, so I have eliminated this part).
When progressively higher frequency tones are played (5 kHz and 10kHz) from the CD, my oscilloscope is showing alternating periods of high amplitude and low amplitude. As far as I can tell, this is not present in the lower frequencies.
However, I'm now stuck on where to go from here. I would like to try and DIY this repair, mostly for the experience, but I could use a few pointers on where to look next.
I've attached a photo of the circuit board for the transport. It seems that most of the decoding logic is done here -- I can't see any DAC chips on the main board. I know that the one chip I can read is the transport controller, but what are the other two?
Thanks in advance for any help!
