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    Jvc pc-x100

    Hello All,

    I have a JVC model PC-X100 unit and the cd player worked for a short time and then just stopped. I replaced the optical pickup which included the laser diode assembly but no luck. The spindle does not rotate clockwise when the unit comes on. I can't find any schematics on this unit and I had to replace the belt in the cassette deck which is a pain to get to buried all the way in front of the unit.

    I guess the next stage of troubleshooting will be to verify the spindle motor works by providing some DC voltage directly to the motor terminals with it unplugged from the control board. The power going into the unit is about 8.5 Vdc and the CD display does show a cd is in the unit but doesn't do much else.

    If anyone has a schematic for this unit it would be greatly appreciated since not even Sam's Photofacts seems to have it.

    Here is a picture of the cd unit removed.


    I have a bad feeling it may be a bad servo processor chip TC9201BF location IC 602.
    Attached Files

    #2
    Re: Jvc pc-x100

    When you replace the optic ass'y did you remove the solder short that protects the optic pickup if there was one? There seems to be a service manual for a PC-X101, I'm not sure how close it is.
    Last edited by R_J; 03-25-2021, 06:32 PM.

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      #3
      Re: Jvc pc-x100

      I bought the complete laser pickup module PN KSS-210A. This assemble included the lens mechanism and the small PC board with 2 Molex 8 pin connectors. I did not see any solder bridges on it. I did test the servo for the platter spindle and it is good used about 1.5 Vdc. My next step is to order both 60 pin flat pack chips location IC 602, and IC 603 being TC9201BF and TC9200BF. I believe 1 chip is a servo controller and the other is data processor. I can't seem to find any data sheets on these Toshiba chips, but they are less than $5.00. It will cost more to ship them than the cost of the chips. I just repaired an RCA 5 disc changer and it was a simple plug and play. All I had to do was increase the laser voltage on the pot under the pickup unit and it worked great. I would like to find out how difficult it would be just to replace the laser diode. Also wonder why this seems to be a common failure in many CD players.

      If all else fails I will get a service manual directly from JVC for about $15.00. If it doesn't violate copyright laws I will scan it in and provide a PDF for anyone that needs it for reference.

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        #4
        Re: Jvc pc-x100

        lasers usually have the signals shorted to ground to protect from static during shipping.
        take a close look at it - and the original one.

        Comment


          #5
          Re: Jvc pc-x100

          Did you remove this solder bridge?
          Attached Files

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            #6
            Re: Jvc pc-x100

            You were absolutely correct. There is a solder bridge I will remove it with my pace solder extractor and verify short is removed with DVM in resistance mode. I will reassemble cd unit and see it the unit functions again.

            Attached Files

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              #7
              Re: Jvc pc-x100

              Originally posted by Schoenradt View Post
              You were absolutely correct. There is a solder bridge I will remove it with my pace solder extractor and verify short is removed with DVM in resistance mode. I will reassemble cd unit and see it the unit functions again.

              Just remove the solder and use a magnifier to check it if you need to, Don't connect your meter or you could damage the pickup.
              You can usually use a solder tip to remove the solder blob.

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                #8
                Re: Jvc pc-x100

                Update the spindle does rotate, but LCD display just shows all zero's and disc stops rotating. At this point I will need to get a service schematic and check all voltages and wave forms going to the IC's. This is better just need to know on how the laser levels and the serial data looks coming from the pickup. I have both new flat pack chips I think one for servo and the other is the codec for the wave file read from the cd track and vector.

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                  #9
                  Re: Jvc pc-x100

                  I checked some specs for the pickup and think I found the problem. It appears that the Sony KSS-210b must be replaced with the same type laser pickup optical assembly. The unit I had was a KSS-201a and they are not the same. I have ordered the original pickup and will update any progress with the unit.

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                    #10
                    Re: Jvc pc-x100

                    I have successfully replaced the main IC's IC 602, and IC 603. The chips lifted quite nice and no traces tore up. The new ones went down well, but no spindle rotation.All I get on the display is CD then all zeros. I also replaced the optical pickup with the original laser unit KSS-210B. Still no disc read and yes I removed the solder bridge and the laser is on and the lens does focus. I have bought a servicing manual that should isolate the problem.
                    Attached Files

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                      #11
                      Re: Jvc pc-x100

                      You need a scope to see if you are reading the disc, The laser being turned on does not mean the pickup is reading any information.

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                        #12
                        Re: Jvc pc-x100

                        Update: I believe I have isolated the problem. It would seem that the laser pickup has two identical interconnection sockets that are 8 pins each. One is red for the laser and the other white for the photo-diode array. The wiring harness plugs are both white and not polarized to the connectors. Plugging the wrong harness into the connector will fry the laser unit putting 5.0Vdc across the laser diode. Also it would seem that the photo-diode array is also rendered useless by plugging the laser diode supply connector to it. I have ordered the original KSS-210B pickup unit and will mark the laser harness with a red stripe using a sharpe marker and verifying the correct harness on the schematic. If I understand how this unit works first the sled servo should park the pickup at home position, then the laser should turn on then the voice coil should focus the beam on the photo-diodes and the platter should spin and a disc read should begin.I used an infrared remote control and could find no indication of conduction from the photo-diodes in circuit biased on. see attached photos. I am showing the KSS-210A module which is for a stationary CD player but the same pinout as th eKSS-210B module for reference.
                        Attached Files

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                          #13
                          Re: Jvc pc-x100

                          Success, Yes the CD player worked and I am convinced that plugging in the wrong wiring harnesses to optical pickup will render it useless. I had to some alignment calibration for tracking monitoring a symmetrical pattern on my oscilloscope but tried several CD's and all were able to play all the way through. I have another unit and it is not working with a new pickup so I am checking the op amps and driver transistors.

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