Sony MDS-503 MiniDisc Deck Test Mode

This document is provided for informational purposes only, the author bears no responsibility for any damage or equipment failure caused by the application of this information.

Here is information (from the service manual) about getting the MDS-503 into test mode, the most interesting feature of which is that you can check the raw bit error rates of blank MiniDiscs with it. Some of this information also applies to the MDS-302, MDS-303, and probably the S30 and S35. It may apply to some other models too, I would appreciate hearing about it if anyone has more information.

First, precautions of test mode:

1. Normal "consumer-mode" control software is not in effect. Disk loading and unloading operations will be performed even if the spindle motor is running. To ensure that you do not eject a spinning disc, always make sure you push "NO" before pushing eject.
2. The write protect tab is ignored in test mode, you can overwrite a disc even if it is protected if you are not careful.
3. You can change the unit's EEPROM settings if you are not careful (this is how adjustments are made), this could quite easily render the unit non-functional.

With these precautions in mind, here are simple instructions for getting in to test mode and checking disc error rates.

Entering Test Mode

1. With unit power off and no disc in the machine, unplug it.
2. Wait 30 seconds for the power supply capacitors to discharge (my ritual, though I am not sure it really helps).
3. While holding the AMS knob in, plug in the unit.
4. Release the AMS knob.

(To exit test mode, press the "REPEAT" button. Machine will go to Standby mode. Unplug unit.)

There are 8 test mode functions, selectable with the AMS knob:

1. TEMP ADJUST - Temperature compensation offset adjustment
2. LDPWR ADJUST - Laser power adjustment
3. EFBAL ADJUST - Traverse adjustment
4. FBIAS ADJUST - Focus bias adjustment
5. FBIAS CHECK - Focus bias check
6. CPLAY MODE - Continuous play mode
7. CREC MODE - Continuous record mode
8. EEP MODE - Non-volatile memory mode *
   * The EEP MODE is not used in servicing. If set accidentally, press the NO button immediately to exit it.

Creating an MO Continuously Recorded Disc

Scroll the AMS knob to CREC MODE.

Insert a disc you do not mind writing on.

Push "YES". Diplay will switch to "CREC IN". You should see the REC light come on, CREC (040) displayed momentarily and a bit of blinking happen. The cluster number counter will be incrementing. (If this does not happen, push "NO", eject disc and try inserting and pressing "YES" again. If you cannot get the "REC" light to come on with CREC IN displayed and the cluster counter incrementing, then exit test mode and try entering it again. The first time I tried continuous recording and playback it did not work and I puzzled with it for an hour before I realized that it does not always enter this mode correctly. Once it works though, it seems to always work during that test mode session.)

With CREC IN displayed and the REC light on, you can push the "display" button to see information about the address that is being written. After you have written some 10s of seconds to disk (the manual says to not exceed 5 minutes), press "YES" again to display "CREC MID". CREC (0300) is displayed for a moment and recording starts. After some 10s of seconds of this, press "YES" again to change to CREC OUT. Recording begins again on the outer part of the disc (from cluster 700). After some 10s of seconds press "NO" to stop recording.

Now you have an MO continuously recorded disc.

Displaying the Raw Error Rate

Press "YES" to change to CPLAY IN. The unit now begins reading back starting from cluster 40 of the disc.

By pressing the "display" button you can select display of either the address info or the error count. Error rate display is:

C1 = XXXX AD = XX

C1 errors should not exceed 50 on the continuously recorded area. If they do, your unit may need adjustment.

Press "YES" again to change to CPLAY MID. The unit now reads back starting from the middle of the disc.

Press "YES" again to change to CPLAY OUT The unit now reads back starting from the outer region of the disc.

Press "NO" when done to exit CPLAY mode.

In the address display modes, h = Header Address, s = SUBQ address, a = ADIP address.

Included below is the information directly from the Service Manual.

4-1. Setting the Test Mode

4-2. Exiting the Test Mode

1. Press the REPEAT button.
2. In case a disc is unloaded, the display "STANDBY" will go on and off.
   In case a disc is loaded, the "STANDBY" is displayed once and the disc is ejected.
3. Unplug the power plug from an outlet.

4-3. Basic Operations of the Test Mode

Function	Contents
AMS knob	Changes parameters and modes
YES button	Proceeds onto the next step. Finalizes input.
NO button	Returns to previous step. Stops operations.

4-4. Selecting the Test Mode

Display	Contents
TEMP ADJUST	Temperature compensation offset adjustment
LDPWR ADJUST	Laser power adjustment
EFBAL ADJUST	Traverse adjustment
FBIAS ADJUST	Focus bias adjustment
FBIAS CHECK	Focus bias check
CPLAY MODE	Continuous play mode
CREC MODE	Continuous record mode
EEP MODE	Non-volatile memory mode *

For detailed description of each adjustment mode, refer to the section on Electrical Adjustments.
If a different adjustment mode has been selected by mistake, press the NO button to exit from it.
* The EEP MODE is not used in servicing. If set accidentally, press the NO button immediately to exit it.

4-4-1. Operating the Continuous Playback Mode

1. Entering the continuous playback mode.
   1. Set the disc in the unit (either MO or CD).
   2. Rotate the AMS knob and display "CPLAY MODE".
   3. Press the YES button to change the display to "CPLAY IN".
   4. When access completes, the display changes to "C1 = XXXX AD= XX".
      Note : The "X" displayed are arbitrary numbers.
2. Changing the parts to be played back
   1. Press the YES button during continuous playback to change the display to "CPLAY MID", "CPLAY OUT". When pressed another time, the parts to be played back can be changed.
   2. When access completes, the display changes to "C1 = XXXX AD= XX".
      Note : The "X" displayed are arbitrary numbers.
3. Ending the continuous playback mode
   1. Press the NO button. The display will change to "CPLAY MODE".
   2. Press the EJECT button and remove the disc.
      Note : The playback start address for IN, MID, and OUT are as follows.

      IN

      40h cluster

      MID

      300h cluster

      OUT

      700h cluster

4-4-2. Operating the Continuous Recording Mode

1. Entering the continuous recording mode
   1. Set the MO disc in the unit.
   2. Rotate the AMS knob and display "CREC MODE".
   3. Press the YES button to change the display to "CREC IN".
   4. When access completes, the display changes to "CREC (XXXX)" and REC lights up.
      Note : The "X" displayed are arbitrary numbers.
2. Changing the parts to be recorded
   1. When the YES button is pressed during continuous recording, the display changes to "CREC MID", "CREC OUT" and REC goes off.
      When pressed another time, the parts to be recorded can be changed.
   2. When access completes, the display changes to "CREC (XXXX)" and REC lights up.
      Note : The "X" displayed are arbitrary numbers.
3. Ending the continuous recording mode
   1. Press the NO button. The display changes to "CREC MODE" and REC goes off.
   2. Press the EJECT button and remove the disc.
      

      Note 1

      The recording start addresses for IN, MID, and OUT are as follows.

      IN

      40h cluster

      MID

      300h cluster

      OUT

      700h cluster

      Note 2

      The NO button can be used to stop recording anytime.
      

      Note 3

      During the test mode, the erasing-protection tab will not be detected. Therefore be careful not to set the continuous recording mode when a disc not to be erased is set in the unit.
      

      Note 4

      Do not perform continuous recording for long periods of time above 5 minutes.
      

      Note 5

      During continuous recording, be careful not to apply vibration.

4-4-3. Non-Volatile Memory Mode

4-5. Functions of Other Buttons

Note:

The erasing-protection tab is not detected during the test mode. Recording will start regardless of the position of the erasing-protection tab when the REC button is pressed.

4-6. Test Mode Displays

1. Mode display
   Displays "TEMP ADJUST", "CPLAY MODE", etc.
2. Error rate display
   Error rates are displayed as follows.
   C1 = XXXX AD = XXXX
   C1 = : Indicates C1 error
   AD = : Indicates ADER
3. Address display
   Address are displayed as follows.
   h = XXXX s = XXXX (MO pit and CD)
   h = XXXX a = XXXX (MO groove)
   h = : Header address
   s = : SUBQ address
   a = : ADIP address
   * is displayed when the address cannot be read.

4-7. Meanings of Other Displays

4-8. Precautions for Use of Test Mode

1. As loading related operations will be performed regardless of the test mode operations being performed, be sure to check that the disc is stopped before setting and removing it.
   Even if the EJECT button is pressed while the disc is rotating during continuous playback, continuous recording, etc. the disc will not stop rotating.
   Therefore, it will be ejected while rotating.
   Always press the NO button first before pressing the EJECT button.
2. The erasing-protection tab is not detected in the test mode. Therefore, when modes which output the recording laser power such as the continuous recording mode and traverse adjustment mode, etc. are set, the recorded contents will be erased regardless of the position of the tab. When using a disc that is not to be erased in the test mode, be careful not to enter the continuous recording mode and traverse adjustment mode.

5-4. Creating MO Continuously Recorded Disc

*

This disc is used in focus bias adjustment and error rate check.

1. Insert a MO disc (blank disc) commercially available.
2. Rotate the AMS knob and display "CREC MODE".
3. Press the YES button and display "CREC IN".
4. Press the YES button again to display "CRED MID".
   "CREC (0300)" is displayed for a moment and recording starts.
5. Complete recording within 5 minutes.
6. Press the NO button and stop recording.
7. Press the EJECT button and remove the MO disc.

5-9. Error Rate Check

5-9-1. CD Error Rate Check

1. Load a test disc TDSYS-1.
2. Rotate the AMS knob and display "CPLAY MODE".
3. Press the YES button twice and display "CPLAY MID".
4. "C1 = XXXX AD = XX" is displayed.
5. Check that the C1 error rate is below 20.
6. Press the NO button, stop playback, press the EJECT button, and remove the test disc.

5-9-2. MO Error Rate Check

1. Load a continuously recorded disc (Refer to "5-4. Creating MO Continuously Recorded Disc".).
2. Rotate the AMS knob and display "CPLAY MODE".
3. Press the YES button twice and display "CPLAY MID".
4. "C1 = XXXX AD = XX" is displayed.
5. Check that the C1 error rate is below 50, check that ADER is 00.
6. Press the NO button, stop playback, press the EJECT button, and remove the continuously recorded disc.

5-10. Focus Bias Check

1. Load a continuously recorded disc (Refer to "5-4. Creating MO Continuously Recorded Disc".).
2. Rotate the AMS knob and display "CPLAY MODE".
3. Press the YES button twice and display "CPLAY MID".
4. Press the NO button when "C1 = XXXX AD = XX" is displayed.
5. Rotate the AMS knob and display "FBIAS CHECK".
6. Press the YES button and display "XXXX/XX c = XX".
   The first four digits indicate the C1 error rate, the two digits after [/] indicate ADER, and the 2 digits after [c =] indicate the focus bias value.
   Check that the C1 error is below 50 and ADER is 00.
7. Press the YES button and display "XXXX/XX b = XX".
   Check that the C1 error is below 220 and ADER is not above 00 every time.
8. Press the YES button and display "XXXX/XX a = XX".
   Check that the C1 error is below 220 and ADER is not above 00 every time.
9. Press the NO button, next press the EJECT button, and remove the continuously recorded disc.

Note 1

If the C1 error and ADER are above 00 at points a or b, the focus bias adjustment may not have been carried out properly. Perform adjustment from the beginning again.

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