Minidisc Repairman Q&A

David Popovits
Sigma D.O. Electronics
3, Sheinkin str. Tel Aviv, Israel
Tel. 972-3-6290339
Fax. 972-3-6203579

July 2000

These questions from readers on these 1 2 3 4 5 6 7 8 pages followed David's original article about portable MD recorder repair

  1. Question Hi David, I have 2 MD Systems in my home . One Portable Recorder and one normal recorder by Sony . The portable one is made by Sharp. Well, I also bought a 8 disk package sony MD-R and I recorded all of them into the Sharp Portable Recorder but there is a problem , 1 disc rarely read the TOC and 90% of the time it says TOC ERROR but in the Sony MD System one , it reads well but this one was recorded into the sharp one. My next 2 discs read into the sharp (recorded into the sharp too) but sometimes part of the tracks keep breaking up. That's strange because both of it read well into the Sony one. The Most Strange is that Pre-Recorded MD's read excellent into the Sharp one and some discs recorded into the sharp one read excelllent too. Why's that? Thanks, Felipe.

    Answer Hi Felipe, You are actually describing one of the well known problems with Sharp MD's. The paper is not long enough to describe what causes this problem and how it can be fixed. Let me list a few.

    1. Spindle motor not moving due to dirt, hair, reset problem...
    2. Dust on the laser unit
    3. Bad calibration
    4. Loosen connectors
    5. Bad laser unit
    I fix many Sharp MD's and I cannot tell that there is one specific reason to the Utoc error problem. I don't have a simple answer. You should repair it at a service point of Sharp or any good laboratory that fixes MD's.

  2. Question Hi David It's truly amazing that I ran across your article on the Minidisc page. First of all, thanks for writing it. I've wanted to see an article like that for a long time and it's great to get a professional perspective on the format! Anyway, the reason I'm writing is in the last week or so my Sony car MD player (the C670) has started rejecting discs and giving me ERROR messages. It will play sometimes, but only after I pop the disc in a few times. Some discs it won't play at all. I came to the web today to see if I could get any info on repairs, so when I saw your posting I thought you would be the perfect person to ask. I hope you don't mind the email! I'm sure I couldn't repair it myself, but do you have an idea where I should contact to get it fixed? It's a few years old so the warrantee is long gone. I'm also wondering if it's going to be expensive to fix. This is my second car MD player and they have both inevitably gotten to a point where they reject discs. Is this inevitable? Is it a characteristic of Sony players? Any advice you might have would be greatly appreciated. Thanks! Mojo Los Angeles

    Answer Hi Mojo, Thanks. Regarding your C670. You can try cleaning the laser unit with an MD disc cleaner. It may help. If this won't improve the situation you can try auto adjustment if you have the service manual. In case it doesn't help as well you will have to take it to a Sony service center. They will charge you multi$, as the problem almost for sure is the need to replace the laser unit. It may be cheaper to buy a new machine. Truly yours,

  3. Question Sorry to bother you Sigma - no doubt you're inundated with queries now. Just though I'd pick your brain on something that's been bugging me. I have an Aiwa AM-F70 which I use for outdoor field recording, often at night. What I really need is for the backlight to stay on permanently for night recording, so I can keep an eye on the meters and adjust levels as necessary. The ideal option of course would be to modify the ROM somehow to remove the backlight timeout (or increase it to, say, 5 minutes), but I guess this isn't easily done? Is the ROM in modern MDs 'flashable'? Or perhaps there is a service mode option for the backlight? Or would it be reasonably trivial for a repair guy to just wire the LCD backlight to power permanently (least preferred option)? The F70 is rated for 4 hours recording with the rechargeable, but I rarely need more than an hour's worth anyway - what kind of time could I expect from a permanent LCD backlight? -- gl

    Answer Hi GL(Please state your name we are not in the spy business) You asked a very specific question, but it has some more general implication so it can help other members of the MD community. It is the question of modifications to make on MD's. Let me tell you this, after repairing so many MD's I thank god for every MD that I see working fine. I wouldn't try to disturb it from its peaceful behavior, even if I know (and I do) how to modificate it. Let it leave, enjoy the situation until you will see a massage saying 'CAUTION!' this massage is bad like the 'UTOC ERROR' on Sharp MD's, or 'DISC ERROR' on Sony equipment. Now to your question: The ROM in MD's is not FLASH. It has external EEROM holding calibration parameters and other information. Some parameters may be changed by the user. If you are not experienced don't touch those parameters, you can kill your MD for good. The light on your MD is a very nice feature. It is not a simple light that can be tied to the power supply, furthermore we do not know what effect can a long period light do to the performance of the MD due to heat from the backlight, neither to the display itself, and to tell you the truth we don't want to know. Use candles. It is very romantic, or may be other source of external light. Truly yours,

  4. Question -- 2ND PART
    The light on your MD is a very nice feature. It is not a simple light that can be tied to the power supply, furthermore we do not know what effect can a long period light do to the performance of the MD due to heat from the backlight, neither to the display itself, and to tell you the truth we don't want to know.
    When the Aiwa is powered off AC, the backlight is permanently on, so it's clearly not a problem. The timeout is only to preserve power when running on batteries. Electrolumiscent lamps do of course gradually 'burn out' over time, but that will happen with AC power anyway.
    Use candles. It is very romantic, or may be other source of external light.
    Not all that easy (or convenient) when recording outdoors on the move. Do you happen to know if the Aiwa has a service mode setting for the backlight that could extend or disable the battery timeout? Unfortunately I've been unable to get hold of an Aiwa service manual, so I can't try it out. And yes, I'm fully aware of service mode implications. -- gl

    Answer HI GL Thank you for your remark. You are right about the AC situation. You cannot change the light time using service mode. If you must have continuos light on the display, I would transmit a false command to the MD using the remote control input or directly into the MD keyboard system. This can be done by an astable timer, having it's 'OFF' time shorter then the natural 'on' time of the MD light. At the end of the 'OFF' time of the astable timer, there should be a 'ON' time of at least 100mS. During this time the timer will imitate pushing one of the keys on the MD and hence turn the backlight on, or forcing it to stay on. If you are good in electronics and do not fear from destroying things, you may try this solution. Truly yours

  5. Question -- 3RD PART Thanks David, that's an excellent suggestion. The details of the Aiwa MD remote controls are already available from the MD community page, so it should be pretty straight forward. -- gl

  6. Question Hi!. I am looking for a reliable MD recorder, but in my country MD is not very popular, and you can only buy units on the airport. They sell the R70, 722 and 821. Which one do you think is the best one? I went to the known problems page on, and since the R70 is a cheap version of the R90, has the R70 got all the problems of the R90? What about the 722 and the UTOC ERROR and TOC ERRORa? Thank you very much. Ignacio Simon. Montevideo, Uruguay.

    Answer Hi Simon, I would choose the Sharp 821, although Sharp invented the UTOC ERROR thing, it seems that the 821 is much better then the 7XX series. The R70/90/91 have all the same mechanism type and the same laser unit, I cannot tell which is the best. Truly yours

  7. Question Dear Mr Popovits, I was ready your replies to several questions posed to you on the Minidic Community Page. I was especially interested in the questions regarding power supply. You mentioned that a 220 > 110V step down transformer with a 110 Sharp adaptor may damage the unit. I live in South Africa using the same type of step down transformer, so far I have noticed (for about 4months) any problems with my Sharp MT-702mk. Since reading your article I'm now interested in getting either a proper adaptor for it or one of your Power Supplies. Are you power supplies compatible with 100/110/240V and if so what is the cost (shipping included). I would like to order one if its possible, just send me a quote and details of how I can pay. Thank you very much Ipinge Agapitus

    Answer Hi, Our power supply will work with any voltage between 100 to 250 VAC on frequency between 47 to 63 HZ. The price is USD 49.00 + p&p. Regarding p&p I will quote soon. Truly yours

  8. Question Hi David, I read through both your articles on and they have been very helpful. However, there's a point that I was hoping that you might clear up for me. In your second article, you mentioned that using a stepdown transformer 220/110 to power a 110 PSU when in a country using a 240 type power supply could potentially kill the equipment. You even mentioned a Sharp 722 and 831 that you had to fix because of the problem. I'm using a 722 with a stepdown transformer too. My beef is this, the PSU that came with the MD recorder is rated at 120v AC, not 110. Wouldn't using a stepdown transformer be actually underpowering the PSU since the output voltage from the transformer is now 110v? How could that burn out the PSU and the MD equipment? Sean

    Answer Hi Sean If the mains supply in your country is 240VAC and you are using a 240 to 120VAC step- down converter, connected to a Sharp 120VAC input PSU, and if the mains voltage in the place you are living is known to be stable you can use it with no problem. If one of the numbers is not the same, pay attention to my warnings. Truly yours,

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