repairing a minidisc using TOC-cloning

what's that all about?

last week i recorded a live-concert with a minidisc-recorder. unfortunatly the first disc wasn't written properly. all MD-players were pretending to see a "blank disc".

i supposed that the recorder didn't wrote the TOC (table of contents). in fact the sound-data was on that disc, but any player denied plaing it because the TOC said: "there's no track".

this howto should give you a generall idea, how to solve problems of this kind. it explains all steps refering to a specific example, but may be "ported" to similar scenarios (e.g.: other hardware)

an alternative solution (software)

while we try to trick the hardware, another method is to use the "testing" or "debug" feature your MD-recorder possibly provides. try to find out wheather your hardware supports it in your manual or the net. this feature is often called "testing-mode" or "debug-mode". you may enter it by pushing various buttons in a specific order or altogether ;-)

in this special mode you may open the recorder, change the disc while the recorder is switched on or position the read-write-unit (and stuff like that...)

my hardware has this mode, but doesn't support the features i need. so let's do it my way...

what we need

in order to hack our hardware and repair the TOC, we need the following things:

all tools you need

that seems to be all. of course, try to get both, left and right hands in order to get the job done ;-) and some patience may be well, too!

what we are going to do

the situation is as described above: we have a recording on a minidisc which reports a blank disc because the TOC was not written. in order to repair it, we simply clone it. therefore we need another minidisc. on that disc we record one track of the full length of the disc. afterwards we can use this TOC and copy it on our demaged disc, so that track will reveal our sound-data. pretty impressive plan, isn't it?

what our main-problem is...

after you insert a disc, your recorder will read the TOC an keep it in memory. in order to clone it, we need to change the disc. unfortunatly when we do this, we will lose our "good" TOC from memory.

the solution is to trick the unit. we want to change the disc, without letting the unit know.

preparing steps

in order to clone the TOC, we need one. so record a track on the blank disc (!) using the full length and the same parameters (e.g. encoding, mono/stereo, ...) as on your demaged disc.

most MD-recorders check the write-protection only on disc-change, so if you experience problems you may try to put some tape on the detector.

detector for write-protection

try to figure out, where the detector is, that reports a disc-change or case-opening to the unit. start by opening the case an looking at the edges inside. look for small switches or someting that may be triggered, if you eject a disc.

the SHARP SR-70 has a small trigger at the middle of the right side, when you look inside the recorder. when it is closed, it is pushed down, so our task will be to keep it down!

lets's clone

ok, now let's get ready to clone... to get this done, we tried over half an hour ;-)

as i mentioned above, we need 4 (or at least 3) hands. of course there are various ways to archive this, but the best method is to work with 2 persons. let's call them person A and person B:

  1. person A (which was me) holds the MD-recorder and uses the pick to hold the trigger down while the case is open and the disc with the one track is inserted. now close the case and keep pushing the trigger down. (that's the exciting part of the game) the MD-recorder should now turn on and start reading the TOC.
  2. now open the case and eject the disc. the trigger is pushed the whole time.
  3. person B might help you to insert the demaged disc.
  4. now edit something (e.g. the disc-name) to make the unit recognize that it has to edit the TOC.
  5. turn the MD-recorder off. before it turns off, it should write the "new" TOC to the disc.
push trigger that recognizes an open case

that's it!