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Thread: MDS-45 - MDS-39 Instrument Questions

  1. #41
    pp Pianissimo samibe's Avatar
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    Corey,

    My organ was doing a similar thing. It took around 5 minutes after I turned the organ on for the card reader to start functioning. Up until it then it would just make really soft strange noises and not read any cards. Once I replaced the battery with a rechargeable one it started functioning correctly (I also had a lamp go out, but that affected different things). I replaced the AV board battery with a 3.6V rechargeable battery. It seems to be working well and saving AV memory for several weeks straight with the organ off.

    Now that my card reader is working, I think I have replicated the effect using a blank ADC card. A blank card in the card reader will make individual notes silent but multiple notes produce really faint sounds. So, I think that the AV board cleared the memory when the organ was turned off (with dead/no batteries) and then it takes several minutes before everything on the AV board starts functioning again after the organ is turned back on.

    A couple of things to try:
    1. Is any sound produced by AV if only one note is played at a time? How about multiple notes?
    2. Test the card reader throughout a practice session. Does the card reader ever read (and the AV board save) a card?
    3. Look through the card reader slot and make sure the bulbs are all working (except for row 11 (second from the right) there usually isn't a bulb there). If some are out, which ones?
    4. Check the voltage to the card reader. Mine had a sticker saying it needed to be at 8V (at the supply), but it read 7.5V at the reader. Too low of a voltage will make the lamps dim enough that a card may not register.
    Sam

    Home: Yamaha P22 (not enough pedals) and a modified Allen ADC-4500 ... for now.
    Church: Allen Protege LD-34

  2. #42
    mp Mezzo-Piano CarillonBells's Avatar
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    UGH - I had a long reply typed and the browser went belly up. I'll try to be more concise.

    No sound seems to be played with one note. Multiple notes do cause faint sound from the speakers with the volume all the way up. This happens with or without the AV-1 card in the cage! The reader has not ever read a card at any time, regardless of power on time or activity.

    I checked the reader from the back, had looked at it previously (from the front) and swear that all the lights were working but now the furthest left (from the front of the organ) is out for certain. Since this is a clocking bit, my understanding is no cards will read under this condition. Looks like I need a bulb! Does anyone know the bulb number? I know it is 12V.

    In other news, I did also find a corroded trace on the AV-1 board, so that most likely will require repair too before things will play correctly. Maybe they will work more than they do now though once I get the bulb swapped.
    Corey

    Allen MDS-41-S with MIDI-DIVISION-II
    Schulmerich Carillon Americana - 61 notes Flemish / Harp / Celesta / Quadra / Minor Tierce
    - MIDI Retrofit finally underway & Moller console in need of refurbishment
    Schulmerich Campanile Digital Carillon (Cast & Harp)

  3. #43
    Moderator jbird604's Avatar
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    Card reader lamps are ordinary #8640 bulbs that are available from many sources on the internet. They don't cost much, and you should have several on hand when you are working on the card reader. As has been noted here, it seems that any time you change one bulb and put the reader back in the organ you'll discover another lamp or two went out while you were doing it! Weird phenomenon, but it happens all the time. Some guys go so far as to change them all at once, even when only one is burned out.

    I'd advise you to change the bad lamp, make sure the reader is clean, blow it out with compressed air, whatever it takes to be sure the light gets through the tiny slots and down to the board with the photo-transistors. Look into the reader from front and back and try to make sure all the lamp filaments are lined up with each other (press down on a lamp gently to re-position the bulb within the confines of the hole it resides in). Then set the voltage as specified on the reader, or use 8.0 volts if nothing is specified.

    Then try reading cards again. It may work just fine, in spite of the possible battery damage in the past. It takes a lot of acid to really eat all the way through a trace.

    Then, you should spend some time cleaning up the socket and the backplane to hopefully head off the kind of trouble that I had. But don't worry about it or let it get you down. Yours is unlikely to be as badly damaged as mine was, as mine was in an Air Force Base chapel and apparently did not get regular attention from a tech, and no one knew the battery had leaked out until it had made quite a mess.
    John
    ----------
    Church: Allen MDS-45 with Allen MIDI-DIVISION-II expander
    Home: Allen Renaissance R-230 with expanded four-channel audio and MIDI-DIVISION-II
    Shop: Bunch of organs in varying conditions, some good, some not...
    Half of an incredible two-man organ service team -- servicing all the major digitals in Arkansas churches
    https://www.facebook.com/pages/Birds...97551893588434

  4. #44
    pp Pianissimo samibe's Avatar
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    Quote Originally Posted by jbird604 View Post
    Some guys go so far as to change them all at once, even when only one is burned out.
    That would be me. Although I replaced mine with diffuse LEDs and resistors (even though that's not how you're supposed to wire LEDs). They have been working really well and it only cost me $12 including lots of extras.
    Sam

    Home: Yamaha P22 (not enough pedals) and a modified Allen ADC-4500 ... for now.
    Church: Allen Protege LD-34

  5. #45
    mp Mezzo-Piano CarillonBells's Avatar
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    1 members found this post helpful.
    A box of bulbs and two bottles of contact cleaner (the good CRC stuff and the really good DeOxit cleaner) are on their way to me. I'll report back once I have:

    1. All the lights working
    2. Verified lamp voltage
    3. A thoroughly cleaned card cage socket
    4. Reinstalled AV-1 board
    5. (And possibly a repaired suspect PCB trace)

    In the meantime I should really get around to moving the new console into place and the old one out. The MDS is still in the dining room and access to the rear is not exactly easy. I don't know how anyone has more than one organ in a home at a time, unless they have a lot more space! There are HC cabinets, benches, pedalboards strewn everywhere!
    Corey

    Allen MDS-41-S with MIDI-DIVISION-II
    Schulmerich Carillon Americana - 61 notes Flemish / Harp / Celesta / Quadra / Minor Tierce
    - MIDI Retrofit finally underway & Moller console in need of refurbishment
    Schulmerich Campanile Digital Carillon (Cast & Harp)

  6. #46
    mp Mezzo-Piano CarillonBells's Avatar
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    The supplies came this afternoon, and I got to work a bit ago. First I replaced the bad lamp, which resulted in THREE more failing as I kept testing the card reader. I replaced lamps and powered them via a 9V battery until they stopped going out. This had a similar functional result, except if I kept key(s) pressed and tried to load a card, I now received weird changes in the muted, synthetic tones and also choppy static related to the speed at which the card went in. I then cleaned the card cage socket and the finger pins using the DeOxit. A little surface abrasion resulted in much of the corrosion revealing the gold/copper beneath it on the fingers on the card. But, still no success despite all the fingers looking clean.

    I was 90% certain that the one trace had been fully eroded by the acid, so I took to fixing it with a jumper wire. Scraped a bit of solder mask off, found a break in the copper, used a piece of wire to jump the gap and soldered in place. Fire up the organ, and load a card. All of a sudden there is a lot more volume and what sounds like a stop! I've been testing with the various cards included with the organ.

    There is one quirk left. It appears that removing the card from the slot changes the final sound. I think it sounds most correct before removal. What is even more odd, is that this artifact only happens with the ADC-era cards. The MOS style cards don't do this (removing them makes no change in the sound). Any thoughts? It sounds like the stop drops by an octave, and playing a note an octave higher upon removal confirms this strange behavior. Also, it appears that although the batteries have a decent charge, they don't preserve the Alterables.
    Last edited by CarillonBells; 07-16-2017 at 05:36 AM.
    Corey

    Allen MDS-41-S with MIDI-DIVISION-II
    Schulmerich Carillon Americana - 61 notes Flemish / Harp / Celesta / Quadra / Minor Tierce
    - MIDI Retrofit finally underway & Moller console in need of refurbishment
    Schulmerich Campanile Digital Carillon (Cast & Harp)

  7. #47
    pp Pianissimo samibe's Avatar
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    1 members found this post helpful.
    I would recheck lamp four, sensor four, or possibly a trace from sensor four. I think the last (33rd) row-4 punch saves the waveform.
    Sam

    Home: Yamaha P22 (not enough pedals) and a modified Allen ADC-4500 ... for now.
    Church: Allen Protege LD-34

  8. #48
    mp Mezzo-Piano CarillonBells's Avatar
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    Lamp 4 is definitely still working, and I verified the bulb height on the entire reader when I did the replacements. If the bulb is lit and at a good height, is there any anomaly that could still cause a problem with the bulb itself? Is it possible to test the sensors in some way?

    Also, do the MOS cards use lamp 4 in the same way as ADC? Because those seem to work properly (and they have a punch at 33rd spot as well). However, I don't think they're being saved in the memory either after cycling the organ's power - so are you saying that punch saves the waveform in memory, but it is possible to be getting tone even if the waveform isn't saved?

    I also thought that the cards were supposed to be read as they are removed from the slot. I can't recall from when I had the 6000 if they did so in both directions like they are in this case. I happen to also have a ADC series Blank card, which does exactly that - it silences the alterable after being read and stays silent even upon removal. I have read a lot of the threads in the past, extensive as they are, about the card reader - but I can't recall enough about the ADC vs MOS cards to know how things are done differently and what would cause a pitch drop by an octave. I wouldn't think there is a way any sensor would work upon insertion of the card, but not detect the same card when traveling in the opposite direction.

    The CR voltage was 7.75V at the reader, I had tweaked it up to the 8V listed on the PCB without any noticeable change in operation. My understanding is that if the voltage is too low nothing tends to work at all. I used a 9V battery for bench testing which might be why some of the working older bulbs decided to quit on me, but I could try running the voltage a bit higher to see if anything changes too.

    I haven't disassembled the entire card reader yet, if that might be productive in light of the above information I could try that too. I did hit it with a substantial bit of compressed air and some dust did come out.
    Corey

    Allen MDS-41-S with MIDI-DIVISION-II
    Schulmerich Carillon Americana - 61 notes Flemish / Harp / Celesta / Quadra / Minor Tierce
    - MIDI Retrofit finally underway & Moller console in need of refurbishment
    Schulmerich Campanile Digital Carillon (Cast & Harp)

  9. #49
    fff Fortississimo davidecasteel's Avatar
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    2 members found this post helpful.
    Actually, samibe, we've discussed this. I think the 4-punch in col 53 is what tells the reader that it's an ADC card--it is the first thing read when the card is removed (and it seems Tone Cards are read on the way out, not the way in). If the row-4 sensor were not working, nothing would be read in (it's the clocking row). Well, possibly it would be read as an MOS card (very badly).

    CarollonBells, the coding schemes for MOS and ADC are very different. The MOS data is a binary code in rows 0-6 (6 is the sign) and the "clocking" is done by the punches in the 8- and 9-row. Row 4 is just one of the bits in the binary code--sometimes punched and other times not. The ADC data is a binary code in rows 0-3 and 5-8 (8 is the sign); row 4 is the "clocking" track and there is a string of 33 consecutive 4-punches in columns 21-53 to perform that task. If the 4-row on an MOS card were not working, the card would still be read, but the binary values would not be correct.

    The last data punches in a MOS card should be in column 51, and there must be an 8-punch in column 52--MOS cards do not have active punches after column 52, but ADC cards have a solitary 4-punch in column 53, with 32 columns of 4-punches and data preceding it (columns 21-52).

    I find the comment that the tone changes between when the ADC card is inserted and when it is removed to be interesting. If it is changing octaves, that would indicate that the punches in the 9 row are involved. One could perform a test by clearing the card reader and connected Alterable stop and then inserting a card--check to see if there is a tone, keeping the key pressed while removing the card. If there were an initial tone (upon inserting the card) it means that some form of reading occurs when the card is inserted--is that tone what is expected? The tone resulting when the card is removed--is that what would be expected? If there were tones both ways, it means that some reading occurred in both directions. An octave change on card removal would happen when the card was about halfway out, when the 9-punches are encountered.

    David
    Last edited by davidecasteel; 07-17-2017 at 06:36 PM.

  10. #50
    mp Mezzo-Piano Pipeorganbuilder's Avatar
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    Thanks David for your detailed discussion of how the cards are read. I have learned a lot from you. Been too many years since I studied this in college.

    Michael

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