Hello all, thanks for your help.
The Cd player is a Denon 1520, it was a good machine - with fine mechanical construction and D/A converters - but
that's true, this is an old machine (1990!!).
The laser pick-up had been changed in the 1996, the CD player could not read few discs, then more, then all of them.
So the (very expensive) replacement.
Now the behaviour is different, but I don't know if the cause is different too.
When I insert a disc in, the player sometimes refuses to read it, the rotation motor doesn't move absolutely (there are only few millivolts between the two poles, and
the motor is OK, not shorted), even if the pick up tries to focus the trace - I can see the lens movement.
When time to time it decides to work, the player work perfectly, all the discs can be read, even the mastered ones.
It seems that there is a sort of correlation between the chip freezing and the operating condition.
I'm not a digital guy, every help will be appreciated!:confused:
Check if the cd runs free (move it by hand) when it is inserted in the player. If it doesn't change a rubber: Denon part number 4620083005. If cd runs free i would suspect the laser unit. I think itís a KSS151A. You can try the following: on the unit there is a small trim pot. Mark it, so you can bring it in the same position afterwards. Turn it a little (i think counterclockwise) and try to play a cd. Try a few cd's. If they start playing better now, it's definitely the laser unit. 1990-1996 is 6 years. 1996-2003 is also 6 years. If you play a lot of cd's...
/Hugo - :goodbad:
Thanks, I'll try this evening.
hmm... actually, if the disc just isn't spinning, it very well could be either the motor or motor driver IC. You should observe the signal going to the motor to see what's happening. If the focus seems to work, then most likley the laser and photodiodes are just fine.
EFM Signal Specification
I seem to have a problem in my CD player either with the EFM signal coming from the CXA1081 or with a processor chip (CXD 1135) sending the data signal to the DAC (PCM 56). The output of both PCM 56 is dead whereas the inpupt signal is permanently high. The EFM output of the CXA1081 has a low level of 1,5 V which does not seem to be right. The high level is approx. 4,8 V. A datasheet for the CXA1081 would be great, too. Does anybody know the specs of an EFM signal ?
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