CD104 reads CDRs but not CDs

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Yes I'm sure.
Now I can't play CDRs! Yesterday I could (even from cold) and today...
What has changed? The radial motor never moves again, it just sticks to the motor spindle as soon as I power up.
In loop A I still measure the same voltages though.
I've ordered a TCA240, we'll see.
 
Right then.
I have re-checked, I've got no AC signal at pins 12 and 13 of TCA240 (service loop A), so nothing either (just noise) at pin 8 of 6215 op-amp.
The real question is: what has it worked with CDRs until yesterday? Is it possible that one branch of the TCA still worked and that it finally gave up the ghost?
More of which when it is replaced, I can't wait.
 
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I admire your determination with this although I still feel the problem will come down to to the RAFOC.

What do Philips call the "focus OK" signal. Have you checked to see if there is any change on that line as the RAFOC does a focus search (with a disc present of course)
 
I think that the tracking loop doesn't work because the transistors in the TCA are open circuit.
Radial error 1 and 2 signals (the difference is the final tracking error signal) can't find their way to the radial motor.
The error signals from the photodiodes are present and conform.
 
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That doesn't necessarily mean its faulty unfortunately. All the evidence is in the voltage and/or dynamic signals present (as viewed on a scope) on those transistors and whatever is present, (whether right or wrong) should enable a good judgement of whether the transistors are functioning correctly.
 
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I'm using the Beogram CDX schematics, which are actually more precise!
The above diagram comes from the CD104 manual.

This is the 303
 

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Its worth looking at and around the zener although low voltage zeners can be very misleading appearing faulty when they are not.

That said, if its passing current then it should definitely develop around 2.4 volts across it, but it will only pass significant current when the TCA is conducting and there is a path to ground. If in doubt connect something like a 10K from ground to the diode to pull a little current and check the voltage again.
 
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OK, probably no real surprise there.

So your back to the TCA. Guess you have to just wait for the new IC now (or try one from another player).

At the back of my mind I still think its RAFOC related because the electronics have "proved" workable by playing CDR.

But keep trying and thinking on the problem :)
 
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