Hello,
I am trying to repair a CD-303 by Philips. When I opened it, I saw that it was already sloppily modded by somebody - lifted PCD traces on the PSU rails, changed electrolytics. The symptoms it gives when trying to play a CD are:
-The CD spins, but the LED display doesn't turn on.
-There is no analog output.
-The CD keeps turning at a constant speed (normal compared to the turning speed I've seen in other players) and there is a 2Hz very quiet clicking sound coming from the head. The head doesn't seem to find a CD track. Selecting a different track doesn't change the head position.
-The CD will keep turning forever if I don't press stop.
-When turned on and pressed play without a CD in the tray, the head moves up and down trying to focus and the head also moves radially, then stops. But I cannot see a laser beam, even in a dark room. I cannot see it with a digital camera either.
What I did attempt in order to repair it:
1.Using the technical manual of Philips CD-303 and CDM0, I
-Measured the main PSU voltages after the regulators and scope-checked them. They seem okay
-Measured the voltage points of the servo feeding the the laser and they were okay. I also measured a voltage drop of 1,8V on the laser diode in reading mode.
-I couldn't figure out the optimal current for the laser, because I cannot find information. The CDM0 manual mentions measuring the current by connection a manufacturer laser simulating PCB with measuring points, which I don't have. I only measured 1V drop across the 15R resistor in the collector of the final transistor feeding the laser, which is equal to 66mA. Is this okay?
-I recapped the whole board with brand new fujicons.
-I changed the trimmer potentiometers.
The result was the same as it was in the beginning. The only small light in the tunnel appeared when my colleagues tried messing up with the focus gain trimmer, the LED panel lit and there was analog output for a little. But it didn't last long for some reason.
I will appreciate any help.
I am trying to repair a CD-303 by Philips. When I opened it, I saw that it was already sloppily modded by somebody - lifted PCD traces on the PSU rails, changed electrolytics. The symptoms it gives when trying to play a CD are:
-The CD spins, but the LED display doesn't turn on.
-There is no analog output.
-The CD keeps turning at a constant speed (normal compared to the turning speed I've seen in other players) and there is a 2Hz very quiet clicking sound coming from the head. The head doesn't seem to find a CD track. Selecting a different track doesn't change the head position.
-The CD will keep turning forever if I don't press stop.
-When turned on and pressed play without a CD in the tray, the head moves up and down trying to focus and the head also moves radially, then stops. But I cannot see a laser beam, even in a dark room. I cannot see it with a digital camera either.
What I did attempt in order to repair it:
1.Using the technical manual of Philips CD-303 and CDM0, I
-Measured the main PSU voltages after the regulators and scope-checked them. They seem okay
-Measured the voltage points of the servo feeding the the laser and they were okay. I also measured a voltage drop of 1,8V on the laser diode in reading mode.
-I couldn't figure out the optimal current for the laser, because I cannot find information. The CDM0 manual mentions measuring the current by connection a manufacturer laser simulating PCB with measuring points, which I don't have. I only measured 1V drop across the 15R resistor in the collector of the final transistor feeding the laser, which is equal to 66mA. Is this okay?
-I recapped the whole board with brand new fujicons.
-I changed the trimmer potentiometers.
The result was the same as it was in the beginning. The only small light in the tunnel appeared when my colleagues tried messing up with the focus gain trimmer, the LED panel lit and there was analog output for a little. But it didn't last long for some reason.
I will appreciate any help.
Hi,
I just read these posts from a couple of years ago.
I have similar problems. I get the correct voltages out of the main PSU, although the pin that should be -18V is actually -16V. Not sure if that would be an issue. I have all the caps now to do a re-capping as that seems to be the first thing advised.
All of my LEDs come on, and when I insert a CD, the player tries exactly twice to work. The first time the CD spins a little, makes a light "beep" and then stops the second it spins a little less, makes a beep then all stops.
I checked the laser output and (with sufficiently low light - 780 nm coming from the laser is on the edge of our "visible" spectrum so hard to see) it is emitting light. At first I thought it might be the laser, but seems not.
So, before re-capping, I'd really like to identify the problem. I find it hard to believe that the recapping will fix it, but I would love to be corrected on that!
Any other tips to get this beauty going?
Thanks, Jim
I just read these posts from a couple of years ago.
I have similar problems. I get the correct voltages out of the main PSU, although the pin that should be -18V is actually -16V. Not sure if that would be an issue. I have all the caps now to do a re-capping as that seems to be the first thing advised.
All of my LEDs come on, and when I insert a CD, the player tries exactly twice to work. The first time the CD spins a little, makes a light "beep" and then stops the second it spins a little less, makes a beep then all stops.
I checked the laser output and (with sufficiently low light - 780 nm coming from the laser is on the edge of our "visible" spectrum so hard to see) it is emitting light. At first I thought it might be the laser, but seems not.
So, before re-capping, I'd really like to identify the problem. I find it hard to believe that the recapping will fix it, but I would love to be corrected on that!
Any other tips to get this beauty going?
Thanks, Jim
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