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Old 31st October 2009, 04:05 AM   #21
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Removed the CDM0 and tested the A, B, C, D photodiodes and they are all good with consistent reverse resistance. If I put a flash light in front of the lens, the resistance drops consistently as well. Seems the laser is just fine.
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Old 31st October 2009, 07:41 PM   #22
oshifis is offline oshifis  Hungary
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Perhaps you could give an external voltage to the MCES by disconnecting the original MCES signal coming from the SAA7020 and apply +5V on the MCES input of the servo board. This would simulate data input rate too low and force the motor to run at maximum speed for a test.
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Old 1st November 2009, 05:29 AM   #23
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I think Q205 (LM339) pin4 uses the FCO signal to generate a kick start to the motor. On my system pin4 measures 6.95V, pin5 6V, pin2 69mV, FCO at 4.6V. When I use multimeter to measure pin4 voltage, sometime I can see motor spins briefly, I guess the measurement cause some interference and generates some MCES pulse.

I will try the 5V MCES idea, oshifs, in your working system, what is the vpp voltage for the MCES signal?
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Old 2nd November 2009, 01:10 PM   #24
oshifis is offline oshifis  Hungary
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MCES is 0V at idle, then alternates between 0 and +5V but only after the motor started rotating. Note that I had to short pin 3-4 on PT10 connector JT06 with an U-shaped wire (black ribbon cable coming from the back RCA panel PW10). This is because the REMOCON signal at pin 3 should be 0, and after I removed the RCA panel, this went up to 5V. If a transistor is faulty on the RCA board, it may produce the same symptom - motor does not start. I would check also the AUTO READ TRAY IN END SWITCH. There are some small black PCB fuses on the power supply board, did you check all voltages?
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Old 3rd November 2009, 05:06 PM   #25
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Yes, I also shorted REMOCON to ground and unplug the 5 pin remote cable completely, but that has no help. I disconnected MCES from decoder board and directly supply 5V to MCES on servo board, the motor does spin at the max speed. From scope I can also observe the initial kick MCES signal generated by Q205 pin2 but it only last a few milliseconds. Once the FCO become high, pin2 goes to 0V. Oshifis, is it possible you check Q205 pin2 on your system to see how long the kick pluse last?

I also observed the SAA7030 runs very hot on the decoder board, and the -2.4V reference voltage is at -2.9V. Is it normal for SAA7030 to run hot?

Really appreciate your help.
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Old 7th November 2009, 07:03 PM   #26
oshifis is offline oshifis  Hungary
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Sorry for the delay. I couldn't measure at Q205 but I think pin 4 on SAA7020 is the same and it is more accessible The signal is 0V when no button is pushed. When I push the Play button, the signal goes to +5V and there is a signal with high duty cycle (zero level is narrow, high level is wider). Then as the motor spins up, it reverses, zero will be wider, high is narrow. Then in 1 or 2 seconds, the duty cycle becomes around 50%.
When I turn on the player with a CD in, or when I insert a CD and the tray is closed, the same thing happens (I think this is why the Tray end signal is called Auto-Read)
I don't know how hot is the SAA7030 because I bypassed it (converted the player to NOS). The -2.4V has +/-20% tolerance, so -2.9V is within limits.
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Old 9th November 2009, 06:20 AM   #27
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Replaced pretty much all chips on the decoding board, SAA7000, SAA7010, SAA7020, SAA7030, RAM chip, but still not working. I don't know what else can cause no initial spin to read the TOC. Bad MCU?
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