The Wayback Machine - https://web.archive.org/web/20011027162909/http://psych.tripod.com:80/md-tech.html
bgcolor=#000000 text=cccccc link=00ffff vlink=00aaaa onLoad="chgpic('pic1','tech-title.gif');"> Written by Shawn Lin
Updated on August 7, 1997.

This is a page of technical information not intended to be useful to the casual MiniDisc user. However, it might be of interest to the brave hardware hacker. Proceed at your own risk, I won't be held responsible if your MD player burns or explodes. Also, most links are direct to various pages from the MiniDisc Community Page maintained by Eric Woudenberg unless otherwise stated.

  1. Test Mode
    1. What is Test Mode?
    2. Entering Test Mode
      1. Sony MDS-501 (linked)
      2. Sony MDS-302/S30, '303/S35, '503, 'JA3ES, and some 'JE500/S37, JE700/J3000, JE510/S38 (linked)
      3. Sony MZ-1
      4. Sony MDX-400
      5. Sony MZ-R3
      6. Sony MDS-JE500 (display Test Mode)
      7. Sony MZ-R30
    3. Test Mode functions
    4. Modifying older Sony MDS-JE500
  2. ATRAC
    1. How does ATRAC compression work?
    2. ATRAC chips
    3. Verified ATRAC Versions
  3. Common MD Problems?
    1. Weird glitches
    2. Won't record!
    3. Will play prerecorded MD's, but has trouble playing recordable MD's.
      Recorders also tend to corrupt the TOC on recordable discs making them useless.
  4. Simple Solutions
    1. Help! My MD recorder erased my disc!
  5. Repairing MD Equipment
    1. How do I repair my MD equipment?
    2. What do I do if it's beyond repair?
1. Test Mode

A. What is Test Mode?
Test Mode is just what the name implies. It is a feature built into the firmware of many Sony MiniDisc players/recorders and it allows a service technician to diagnose and fine-tune the MD hardware. On some older MD machines, Test Mode just displayed information which would allow for manual adjustments using tiny trimpots mounted on various circuit boards. Later model MD machines store adjustment information on an EEPROM (Electrically Eraseable Programmable Read Only Memory) which is loaded on powerup and can be adjusted in Test Mode. Some options and functions available within Test Mode can erase a recordable disc on recording-capable MD equipment. To be on the safe side, always invoke Test Mode with no disc or a scratch disc. Also, do not change any Test Mode parameters unless you know what you are doing! You can cripple your machine this way.

B. How to enter Test Mode?
This information is documented on Eric Woudenberg's Test Mode pages. To reduce redundancy, I'll just provide links to them rather than re-explaining it.
1. Sony MDS-501 Test Mode. (link)
2. Sony MDS-302/S30, '303/S35, '503, 'JA3ES, and some 'JE500/S37, JE700/J3000, JE510/S38 units. (link)

3. Test Mode on the Sony MZ-1 (first portable MD recorder)

To activate and deactivate Test Mode.

  1. With an AC cord unplugged and battery removed, short JR106 with a solder jumper.
  2. Plug in the AC cord, and the TEST mode will be activated.
  3. To deactivate the TEST mode, remove the solder jumper.
4. Test Mode on Sony MDX-400 (4 MD changer car stereo)

There are two Test Modes on the MDX-400.
Set (entire system) test mode setting by:

  1. Press preset button 4.
  2. Press preset button 5.
  3. Press preset button 1 for about 2 seconds.
  4. All ON appears on the display, and test mode becomes set.
To cancel the test mode, press OFF button or RESET button on the HIDEAWAY (tuner) unit.

Setting of MD (Indash) test mode

  1. Connect Pin 35 of IC310 to +5V (positive pin of capacitor C332).
  2. Press the reset button of the HIDEAWAY (tuner) unit.
  3. Test mode appears on the display, and test mode becomes set.
To cancel the test mode, disconnect Pin 35 of IC310 and press OFF.

5. Setting the Test Mode on the Sony MZ-R3 (Recording Walkman)

  1. Short circuit the soldering bridge of TAP801 (MODE) on the main board. (connect pin #46 to GND) and turn on the power.
  2. When the test mode is set, the LCD will display the following:
    ver 00.09
    00
  3. After the ROM version is displayed, there will be a pattern of all ON and all OFF. You can pause the display by pressing the PAUSE button.
There is also another (possibly the same?) test mode that can be accessed by:
  1. Make sure the HOLD switch is ON
  2. Connect a 24kohm resistor between pin 2 and 4 on the remote control input (pins are counted "1-2-3-4" directly after the audio jack).

6. Front End Test Mode on the Sony MDS-JE500/510

The MDS-JE500/510 has an additional test mode to allow testing the display and front panel keys.
Using the front panel test mode:

  1. Unplug the power cord.
  2. Press and hold both the AMS knob (ENTER) and REC.
  3. Plug in the power and release both buttons.
Now, the display will briefly display a list of tests. When finished with each test, press the AMS knob (ENTER) to go onto the next test.
"Key Check". All the display elements will be lit. Press every button on the front panel and parts of the display will go out. Press the AMS knob (ENTER) when finished. If all goes well, the display will say "Key TEST OK!".
"JOG&LEDCheck;". Turn the AMS knob and the power LED will change from red to green and vice versa.
"Segment Test". Displays the segments for you to make sure they work.
"SlideSW Test". Allows you to check the slide switches (TIMER, INPUT, REC MODE). Slide each switch and see what it does on the display.
"Remocon Test". This tests the remote controller, it asks you to push Scroll. After pushing scroll, the tests are ended and the screen will say "end".
Unplug and replug the power cord to go back to normal operation.

7. Test Mode on the Sony MZ-R30 (Recording Walkman)

To set test mode, connect a 24kohm resistor between pin 2 and 4 of the remote control connector.

To disable Test Mode, remove the battery.

C. Test Mode Functions

To avoid redundancy, check out the links in Section B for Test Mode functions and descriptions common to most models.

MDS-JE500/510 additional Test Mode functions (link).

MZ-R30 Test Mode Functions As documented by Leon Woestenberg:

TEST MODE

- Display alternates between:
  - "Ver 01.60" version notice (of control logic?)
  - All display elements on
  - All display elements off
  * Keeping PAUSE pressed pauses this alternation.
  * Pressing |<< brings unit in ASSY MODE
  * Pressing >>| brings unit in SERVO MODE


ASSY MODE

- Display says
  - "Assy Mode"
  - SHUF
  - 40 FF
  * Pressing STOP will move head to track 0 and back to track 40 (?).
    - Display shows 00 FF, then 40 FF again, while doing so.

  * Pressing PLAY will do a magneto-optical testrun, thereby OVERWRITING
    the inserted MiniDisc with a test signal.
    - Text Display show "MO RUN" during this test.

    - MZ-R30 mechanisms make a noisy sound.

    - Display shows numbers 31 to 38, then 61, then 82, both for a longer time,
      then 39 short, 82 long, d0, 42, 43, and stops again at 00.

    - Display then shows "MOmode OK" or MOmode NG" to indicate success or
      failure.

SERVO MODE

- Text display shows "SERVO".
- |<< and >>| can be used to move the head left and right. WARNING: Don't
  force crossing begin and end boundaries.
- STOP and PLAY will traverse through a list of parameters. STOP decreases
  the parameter number, PLAY increases it.
  - Display shows: "XX YY"
    - XX is the parameter number
    - YY is a value, and is displayed:
      - not at all
      - static, which means a read-only value (?)
      - flashing, which means you can adjust this:
        - !! Write down each XX YY pair before you start playing around.
        - Use VOLUME DOWN and UP to adjust a parameter.

        - Mine showed: ( means flashing, i.e. adjustable value)
          10
          11 05
          12 05
          13 FF
          14 42
          15         (tick sound heard)
          16 32
          20
          21 <08>
          22 <48>
          30
          31       !! skips to 32 and runs servo motor (?)
          32 <10>
          33 <0a>
          36 <08>
          37 <2b>
          38 <28>
          39 <0a>  !! shows "XXX YY ZZ" in display, XXX increases, ZZ changes
                   PAUSE DOES "AUTO ADJUST"
          40
          41       !! skips to 42 and runs servo motor (?)
          42 <11>
          43 <08>
          44 <08>
          45 <21>
          46 <27>
          47 <00>  !! shows "XXX    ZZ" in display, XXX increases, ZZ changes
                   PAUSE DOES "AUTO ADJUST"
          50
          51
          52 <11>
          53 <17>
          54 <08>
          55 <29>
          56 <21>
          57 00    !! shows "XXX    ZZ" in display, XXX increases, ZZ changes
                   PAUSE DOES "AUTO ADJUST"
          60
          61       !! loud mechanical noise
          63       !! loud mechanical noise

D. Modifying older Sony MDS-JE500
Many older Sony MDS-JE500 recording decks do not support Test Mode. When trying to get into Test Mode, the display just blinks "STANDBY". This is because certain older JE500's manufactured on and before August 1996 have an extra circuit board that causes it to skip Test Mode and go right to Standby Mode. If you greatly desire the ability to get into Test Mode for some reason, this extra circuit board can be disconnected to give the electronic equivelent of a newer Test Mode capable JE500.

1. Remove the top cover.
2. Locate circuit board ">PF-LP<" (Sony Part #1-664-290-11).
3. Be sure to write down the EXACT location each wire from the daughterboard is soldered onto the MAIN board. This is necessary in case you have to reconnect the daughterboard.
4. Desolder all of the daughterboard's wires at the MAIN board.
5. Jumper JW102 has been cut at the factory. This jumper must be restored. You can easily do this by soldering a short length of wire to the remaining jumper stubs.

After performing that modification, your JE500 will now enter Test Mode by using the normal procedure. I have no idea why that board is there. It could be some kind of bugfix, it could be a way to prevent people from screwing up their machines in Test Mode, it could be anything. I have only tested a JE500 for 15 minutes after removing this board, and it seemed to work fine.

2. ATRAC

A. How does ATRAC compression work?
This information has already been written, so I'll just link to it.
ATRAC Info (link)
See also:

Perceptual Coding (link)
Masking Effect (link)

B. ATRAC Chips
This information only applies to MD equipment using Sony chips. There is less information available on Sharp's ATRAC chipsets.

ATRAC 1CXD2525R - 80 pin LQFP. EFM/ACIR Encoder/Decoder
CXD2526Q - 80 pin LQFP. Shock Proof Memory Controller
CXD2527R - 100 pin LQFP. ATRAC (one per channel)
CXA1602R - 48 pin LQFP. Servo
ATRAC 2CXD2531R - 80 pin LQFP. Shock proof Memory Controller, ATRAC Encoder/Decoder.
CXD2525R - 80 pin LQFP. EFM/CIRC.
CXD2526AR - Shock-Proof Memory Interface.
CXA1082BQ - 48 pin LQFP. Digital Servo Controller.
ATRAC 3CXD2535BR-1, CXD2536R
ATRAC 3.5CXD2536A
ATRAC 4CXD2650R - 100 pin LQFP. Digital Signal Processor, Digital Servo Signal Processor, EFM/ACIRC Encoder/Decoder, Shock-proof Memory Controller, ATRAC Encoder/Decoder, 2M Bit DRAM.
ATRAC 4.5CXD2537R

C. Verified ATRAC Versions
I have included this section because sometimes Sony recycles older ATRAC versions into newer play-only equipment. The following table lists equipment I have disassembled and actually verified what version of ATRAC it actually uses.

UnitTypeYear ModelSony ATRACActual ATRAC Chip
Sony MZ-1Recording Portable1992-931
Sony MDX-400Car Deck1994-972
Sony MDX-C150Car Deck1995-972CXD2531BR
Sony MZ-E3Play-only Portable1995-963
Sony MDS-JE500Recording Deck1996-974
Sony MDS-JE510Recording Deck1997+4

3. Common MD Problems?

A. Weird Glitches
I don't know much about them, but apparently they are firmware-based. Some MD recorders have bugs and inconsistencies.

Typical Problems

  • Some discs show less blank space remaining on different records. This is quite possibly due to newer recorders counting blank space different than older recorders and is not actually a bug.
  • Some people have reported tracks or whole discs accidentally getting erased. I'm not sure how or why this happens, but it tends to happen on portables more than decks.
Known Sony MDS-JE500 Bugs
  • Older MDS-JE500 had a problem that while titling during recording, a "Retry Error" would occur.
  • Certain older MDS-JE500 also had a problem where even when an unprotected recordable disc is inserted, hitting REC still results in "Protected".
Solutions for either problem are either live with it, or get warranty service.

Known Sony MDM-X4 Bugs

  • When attempting to delete a section from the audio, (pressing "mark" and the "in" and "out" points), I'm getting an "invalid" message. This happens about every fourth or fifth edit - not always. - Joe Hammer .
Joe later came to discover that nearly all of them do this. No solution except to switch to a different brand of multitrack recorder.

B. Won't Record!
There are two possibilities when a MD recorder won't record.

1. Defective component - A few people who have owned the Sony MZ-R2 can attest to the fact that the laser diode assembly can wear out after only a few years. They discovered their MZ-R2 wouldn't record, and when sending it to the Sony Repair Center, it was diagnosed that the optical assembly needed replacement at about $500. Obviously, it would be cheaper to buy a new Sony MZ-R30! The cause of the problem is probably either a design flaw, or cost-cutting. Apparently the laser diode, which needs to be driven at a higher power to record, was not as robust as its designers intended.

2. Misaligned/Maladjusted component - Over time, components can age and require recalibration. However, one problem I have experienced is an inability to record on a MDS-JE500. The symptoms: It would appear to be recording, but when I went to play back the song, I got nothing. The clock would be stopped, or advanced very slowly. On occasion, it would make a few squeaks. Upon ejecting the disc, the TOC would be written. When the disc was reinserted, it would show up as "Blank Disc" or "Disc Error". The previous contents were destroyed. The actual problem: The magnetic recording head had gotten dislodged and was sitting atop a little plastic "stick". I pushed it underneath the "stick" and that fixed the problem. The cause: The head had been dislodged in shipping, and would be very likely to happen with a light shock to the side.

C. Will play prerecorded MD's, but not recordable MD's.
This seems to be an all-too common problem.

The defective MD machines seem to exhibit some or all of these symptoms:

  • Light to severe skipping on recordable discs, no problems with pre-recorded ones.
  • Occasional or often get "Disc Error" messages with recordable discs only.
  • Skips at random times on random tracks with no apparent outside influence.
  • Can be coaxed into working fine by switching discs.
A recorder also adds any of the following symptoms:
  • Will not record properly
  • Corrupts recordable discs when not write-protected.

The following models are notorious for having this problem, and be wary when buying them used without warranty!

  • Sony MZ-R2 recording portable
  • Sony MDX-400 4-MD car deck
  • Sony MDX-100 single MD car deck
  • Sony MDX-C150 single MD car deck
  • Sony MDS-302 recording deck
  • Sony MDS-JA3ES recording deck
Most likely problem is an aging of components, more specifically, the laser assembly. The problem seems to be a weakened laser. This would make recordable discs more difficult for the MD player to read because they are less reflective and require more laser power. This also explains why pre-recorded discs play just fine since they are much more reflective and are manufactured the same as CDs. This happens a lot in not just MD equipment, but CD players as well. The main difference is that the lower power required to play CDs causes the laser to age less quickly and last longer. Plus, the CD is much more reflective so even if the laser is aging, the symptoms are much more subtle. This is also true if you mainly play pre-recorded MDs on an MD player.
On the other hand, it seems like perhaps maybe it isn't the laser itself that has aged, but maybe something else? Sometimes you can rule out a serious laser diode problem by seeing if a recordable disc will play with the unit turned upside down. If it does, obviously the laser is producing enough output to work. So the cause of the problem seems to be the inability of the focus or tracking coils to maintain position (much more critical with recordable MDs).
Whether it is a weakened laser or weakened coils, both are integrated into a non-serviceable laser assembly called the "optical block". Sometimes recalibration to account for the weakened optical block will fix the problem to a great degree, but not usually 100%. Most people have reported that the solution to regain 100% functionality with all discs was to replace the optical block. The optical block costs about US$170 from Sony and installation, calibration, and all labor charges brings the grand-total to a range of US$300-500.
This problem seems widespread in only the 2nd and 3rd generation MD equipment, but not the first and fourth generation. The problem seems to indicate either poor-quality components or faulty design on the part of Sony Corporation. It is entirely possible that in a year or two we will see fourth generation machines developing this problem. The problem is so wide-spread, Sony should offer a free recall campaign to correct the problem.

Just for your information, here is a chart showing what optical block is used in which Sony machine.
Sony Optical Block Chart
Block ModelSony Part #Used in...Known to fail?
KMS-130BX-4944-237-1MZ-1NO
KMS-150AMDX-U1YES
KMS-151A8-583-007-11MDX-400YES
KMS-190A?-???-???-??MDH-10Unknown
KMS-193A?-???-???-??MDX-C150YES
KMS-201A?-???-???-??MZ-E3YES
KMS-210A8-583-009-12MDS-302, MDS-JA3ESYES
KMS-260A8-583-028-01MDS-JE500/510NO

4. Simple Solutions

A. Help! My MD recorder erased my disc!
If your MD recorder erased your disc somehow or you erased it on accident, there is an Undo function you can try.
On the MDS-JE500/510 this feature is invoked by pressing EDIT/NO repeatedly until "Undo ?" appears in the display. Then press YES again. If all went well, you should see "Complete" in the display.
For other models, using the Undo feature should be listed in the manual.

Can't UNDO? There is a procedure using Test Mode that should work.
See Martin's MiniDisc Page for more information on this procedure.

5. Repairing MD Equipment

A. How do I repair MD equipment?
If you want to attempt to repair your own MD equipment, you will need the following to achieve success:

  1. Must be brave! You won't do a good job if opening it up sounds intimidating.
  2. Steady hands. Very important with the tiny surface mount components used today.
  3. Basic understanding of electricity. Do NOT try to fix an AC powered MD deck if you don't know what you can and cannot touch inside with the power on.
  4. Soldering skills. Many repairs will require soldering skills to replace bad components.
  5. Basic tools: digital multimeter, precision screwdrivers, soldering iron, solder
If you're ready to give fixing your broken MD player/recorder a try, here are a few helpful reading materials to help you get started:
CD Player Repair FAQ by Samuel M. Goldwasser. Not exactly MD-specific, but nearly everything in this FAQ also applies to MD as well.
Fil's Home Page - Contains many notes on electronics and electronics repair. Nothing too specific, but lots of helpful information here. Also contains the full suite of Samuel M. Goldwasser's repair FAQs.
sci.electronics.repair - This is a UseNet newsgroup with many helpful people that will assist you in a proper diagnosis. Mr. Goldwasser frequents this newsgroup often and usually offers assistance to anyone who needs it. He is a very kind, knowledgeable, and helpful person who has helped myself and others fix many problems.

Service Manuals are also a necessity for detailed information on calibration or for part numbers of proprietary components. Service Manuals contain schematics, disassembly diagrams, part numbers, parts lists, waveform pictures, calibration instructions, etc. For Sony equipment, they are available from Sony Parts 1-800-488-7669 for a cost of about $20-25. They can also be ordered by any local Sony Authorized dealer to avoid shipping costs.

B. What do I do if it's beyond repair?
If for some reason you are sure your MD recorder/player is beyond reasonable repair, by all means do not just throw it away! Please consider donating or selling it to me instead. At the very least, I will pay shipping. I will use it to learn more about MD machines and add some more info to this page. If you have some broken MD machine you want to sell, just email me at lin@science.smsu.edu and let me know how much you want for it.
Sorry, donations aren't tax deductible.