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NGY

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Posts posted by NGY

  1. BG1 is a solder joint. Sony has them at many places, it is part of the EDS protection during repair. Normally, one has to remove the solder (thus disconnect the two parts of the circuitry) before replacing the OWH, then resolder afterwards.

    Next time I want to check the signals on the output of the bridge at those test points, then the inputs of the logic IC, the two signals coming from the ATRAC: "EFMO" (at TP307) and SCTX (at TP301). I cross my fingers, these last two will be alive, should any or both not, then yes, game over.

    I can hardly wait for having an oscilloscope, at this point a simple DVM is not enough for such tests.

  2. Thanks for your reply. These days are kinda busy, I hope I can continue working on this deck at the weekend, and hopefully sometime next week I will possess a scope too. In the meantime, answering you I added some more details. As soon as I  can have my hands again on the machine, I will report here where I am  progressing with the repair.

    "I'm wondering if the abuse to the machine was it being plugged into the wrong mains power."
    The deck is a European version, was also originally purchased over here (mainland, 230V across, fairly flat), so such a change in mains voltage should not be an issue, unless the machine has got a spike or shock earlier, that hit some recording related parts. I will check all individual power rails' voltages at more points to exclude this possibility - already measured the supply voltage lines on the ribbon cables, all seemed to be in order.

    "If you can see the seconds clicking off on the display then all should be OK except the OWH."
    That's right, when in recording mode, seconds were clicking just as if there was no problem at all.

    "Having no overwrite means that you never get to record the TOC"
    And, that actual magnetic polarizing does not happen during recording/writing, only the laser heats and erases the bits.
    I made two experiments: first I took an earlier recorded disc with several tracks on it, put into this 530, erased one letter of the title to make a change to the TOC. Upon ejecting and reinserting the disc, it showed "blank disc" (I certainly restored my test disc cloning back its TOC I saved prior probing).
    Then I made a short recording on a brand new, never used blank disc. The result was a blank disc. Then cloned a matching TOC onto this disc in another deck. While cloning was successful, I could not play back the disc - the drive was audibly seeking back and forth, and the time display did not progress.
    These results told me, that the OWH did not function for some reason (though the head itself was operable, proven in another deck), and rest of the machine seemed to be OK.

    "There's nothing to adjust on the OW circuit"
    This is an important piece of information for me. At the end of the day, this was my assumption too.
    I thought whether there was something to adjust on the OWH/OP relative positions and focus, but probably there is nothing there either, as the OWH is mounted at a predefined position on the OP arm, and the writing coil covers a fairly large area, way larger than the tip of the focused laser beam. The focus of the laser then might not be an issue, if the drive can read both kind of discs properly.

    "check the signals from the microswitch which controls whether writing is disabled - maybe it's (physically or electronically) "stuck" and somehow the OW never gets enabled."
    That's a good point - learning from the issues with the 510, I already took the switch panel off, and checked all switches, but found no problem there. However, I cannot yet measure, whether the control IC's relevant input circuitries are in good order or not. Once I attempted to fix an S38 that did not respond to any of the front panel buttons, then it turned out, that two of the key matrix inputs on the main IC were dead, i.e., internally shortcut to ground. I hope it is not the case now, because then no way to repair it (frugally, I mean).

    "I don't know where 7350 is coming from, can you give us a better locus for this error number?"
    7350 is displayed as a C1 error in self recording/playback check, while this value must be <80. The same time, ADER is 0, and that is a good value. A Sony technician wrote once somewhere on the net (I keep re-searching for the link), that C1=7350 means "does not read correctly". It is then not an error code, but rather a bad value of an error variable. Will take a photo, when I am back to playing with this deck, how it is displayed.

    So much for now, I will get back soon. Thanks again for the care and the ideas.

  3. Greetings to everyone - I am a newbie here, though not new to Minidisc. I entered the MD world in about '96-97, when I bought my MZ-R3 in a Duty-Free shop at London Heathrow, while waiting for connection. It was an amazing piece of kit that time, and I must say, the MD technology is still a fantastic engineering achievement in my eyes.

    I have been reading the forums since about two months now, mostly seeking for repair tips - having a couple units I bought recently second hand (mostly fairly cheap), with the intention of bringing them back to life and preserve. And, already a big "thank you" for the forum - I already managed to fix my MDS-JE510 unit, that did not accept discs, ejecting all with C13 error. Following Jim Hoggarth's instructions, I turned it back to fully functional, and it still holds since then.

    Now, I am in a project of repairing the unit in the subject. I tried a couple of things but still not yet there. This 530 arrived with a broken OWH (Overwrite head), that had clear signs of previous failed repair attempts, thus the machine was play only, but otherwise working OK. As a first step, I took a 100% OK OWH from a fully functional 520 unit, built it into the 530, but then the 530 still did not record, i.e., when ejecting after a record session, the disc remained blank. Testing the same OWH back in the 520: all OK. (BTW, I finally fixed that broken OWH from the 530, tried also in the 520, and the 520 just can record properly with this repaired one.) Error history in Error Display Mode shows E04 and E09 alternating ("Address cannot be read" and "Playback retry error" respectively).

    Then I took the service manual and began performing the checks (except for laser power and traverse signal, as my old oscilloscope gave up recently), and the only error I could find  is a "7350" error in self-recording (and focus bias) check, obviously, as no data was written to the disc. Apart from that, the deck seems all fine, functioning as it has to. Having the idea the focus could be out of range, first I created a continuously recorded test disc in a spotless 330 unit, then put it back to the 530, and checked the focus bias with that. It went all OK, continuous play test showed all error rates below factory specs. Repeating the same procedure with a continuously recorded disc made with the 530, I got back to the "7350" error - as nothing was written on the disc.

    I am stuck here, I have no idea, why the unit is not recording, as everything seems OK. This particular deck run only 38 hours of recording, and 418 hours of playback, and looks like new - would be great to have it fully functional again, especially for the Type-R ATRAC.

    The schematics of the OWH drive circuit is fairly simple, pairs of diodes and transistors, plus a capacitive coupling to the writing coil - all these parts look robust on the BD board, I cannot even imagine they blew (or the IC driving the transistors?). I could only check the diodes, they seem to be OK, however, I have no means to check these special transistors. As soon as I can get my hands on another oscilloscope, will check the writing signals on a good unit, and compare with the 530, to see ho far the signal gets, and when it stops.

    But before that, if anybody with some experience can give me their view, whether I am going the right direction, or something else needs to be checked/adjusted. I am aware, that the time I will probably spend on fixing this may not worth it, and I may buy another unit at a lesser cost, but hey, this is a hobby, and I looked for some challenge :-) . Should I not succeed, I will put up the unit for parts, if it can help others to fix theirs.

    Thank you in advance and apologies for the fairly long post.

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