I see we're both on the forum and posting, so your post answered at least part of my question. Let me know what happens if you boost the voltage. I may have something else to recommend after attempting the LED cure today.</P>
John</P>
John
---------- *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!
interesting thread. David's explanation settles the question I'd had about whether MOS was 7 or 8 bit...-63 to +63 is 7 bit. But depending upon how well the resistor ladder converter was made it might not have sounded "as bad" as that implies...and obviously didn't because the line was a success. MOS cards working in ADC but not sounding as loud would make perfect sense as they would be missing the 8th bit that was added for ADC. ADC also had a longer sample word (perhaps as long as 256) with the electronics filling the blanks between points - there wasn't enough room on the card which is why the MADC stored-sample version came about. (As Mr. Greenwood the design engineer explained, when a cheap 256K memory chip was released!) The long sample word probably explains the frustration I had with the sound quality of my MADC organ...most of the notes above the C2 register were very clean sounding and might as well have been 16 bit depth samples, but E & Fs were grainy and noisy and indicative of the 8 bit origins of the system. (SACD after all, although not PCM encoding, is a super super fast 1 bit data stream. Proof that ultimately what matters is the amt. of data you're pushing, not how that data is coded. )
</p>
Philip -- Before you replaced the lamp, what did you get from the alterables? I think you said it was a reed-like tone, but I'm wondering about the volume level. Was it louder than the more correct tones that you are getting now? Or was it also on the soft side?</p>
[/quote]</p>
Hi John,</p>
Volume-wise, it was much louder, the correct volume. But tonally it was messed up.
</p>
John, those holes beyond column 52 (the last one with voice data) are used to contain the information about what the stop name is. Some cards actually have the stop name inHollerithcode there and the cards were run through a Card Interpreter machine that printed that information on the top edge of the card. Later cards seem to have a stock number or some such coded there instead of the actual stop name, and I presume a computer setup was used to print the stop names on them. For example, I have an image of a "Cornet V" card that another member sent me and the Hollerith code in those columns decodes as "R18.0 S00F9194". The "R18.0" might refer to that being the 18th revision, or maybe the 18th release (production run?); the rest may be a key to the stop name in a table, or just an Allen part number.</P>
If the problem is in the reader circuitry or the MOS board, replacing the lamp array with the LED array will not fix the problem (although it would prevent any future problems with lamps burning out).</P>
I wish I could offer more help, but I really cannot understand how a failure to read one or more card rows correctly (plugged reader holes) could affect only the volume of the stop: a failure of either the 8 or 9 row sensing would keep the card from reading in at all; a failure of row 6 (the sign bit) would change all negative values to the result of adding those values to +64 (subtracting the absolute values from +64) and that would have a disastrous effect on the waveform; failures to read punches in the other rows (5 through 0) would have varying effects by reducing the values read by powers of 2 and distorting the waveform. A failure of detecting punches in rows 5 or 4 would have a big effect on both the waveform shape and the volume. (Row 5 is the MSB of the binary value.)</P>
John - I'd be curious to get more information about the kit. I presume that it is simply a set of LEDs and voltage dropping resistors. A brief search reveals that high brightness white LEDs are being used. It is an elegant solution to having to replace lamps all the time, and if anything, the directionality of the LEDs would be an improvement for separation between rows.</p>
Also, as far as Philip's troubles are concerned - when I first powered on my ADC-6000 at the church and it had not been used in some time, the alterable voices sounded faint and strange. Once I figured out how to program them, though, everything was okay. Is there a battery backup on the MOS instruments for the alterable like that on the ADC? I would think if it fails it could do strange to the circuitry that stores the waveform data, depending on how it is exactly done. Also, can anyone comment on whether the photo transistors ever go bad? And finally, is it possible a bulb with less significance to the waveform data has already kicked the bucket after the other was replaced?
</p>
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)
LED kit -- we did not use it today, as the problem turned out to be not on thereader. However, the instructions are fairly simple, though dismantling the reader is required. One must enlarge the holes into which the lamps are inserted because the LED's are bigger than the lamps. A 13/64 (or #9)drill bit is needed for that task.</P>
We are going to try this at the first opportunity, but it doesn't look too hard. You just have to carefully disassemble the reader and make note of how each screw or bolt and washer goes in. After the drilling it would of course be necessary to thoroughly clean up the parts because the tiniest bit of drilling debris could block a slot.</P>
Yes, the kit consists of nothing more than the 10 LED's and 10 -1K resistors, along with the instructions for properly orienting the LED's and soldering a resistor in series with each one. Not really $25 worth of stuff in there, but Harrison deserves a little profit for figuring this out and putting it all together in a kit!</P>
MOS card-reader and alterable voices do not have battery backup. They reset to blank when the organ is powered off and must be re-programmed each time. And the alterable voice memory and processing are right on the MOS board and get sent out to the same DAC board as the resident voices. So there isn't any way to separately adjust their volume. Wish that weren't so, and we'd conclude that Philip only needs to clean that pot or lube a cable or connector.</P>
I suppose another lamp may have burned out, as that often happens when I replace one. Only Philip can tell us about that. It's so strange that the volume was normal before he replaced that one lamp. I really don't know what to make of that unless another lamp went out and it was more critical than the one that was already out.</P>
Or maybe some debris got down into one or more holes. The slots above the phototransistors are exceedingly small slits, and a bit of fuzz can block the light.</P>
I suppose the phototransistors can get defective, though I haven't seen that happen.</P>
John</P>
<P mce_keep="true"></P>
John
---------- *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!
I don't suppose it is possible that in reconnecting the cable to the card reader that it didn't go right? I would expect that if it had been connected upside down that the lamps probably wouldn't light, but maybe some of the connections didn't "make"?</P>
Yes, David, that's another possibility. Philip is going to have to learn on the job, and learn quickly!</P>
John</P>
John
---------- *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!
Perhaps working on it just before services is not the best plan. Could you manage doing it (a) when no one else is around to watch, and (b) when doing so would not suggest a problem at worship time?</P>
I believe I have just confirmed a Facebook Friend request from you, by the way (Philip).</P>
Perhaps working on it just before services is not the best plan. Could you manage doing it (a) when no one else is around to watch, and (b) when doing so would not suggest a problem at worship time?</p>
I believe I have just confirmed a Facebook Friend request from you, by the way (Philip).</p>
David</p>
[/quote]</p>
Hi David, yes, that was me. Thanks! I appreciate your "friend"ship.</p>
It is difficult for me to work on the organ at any other time than Sundays or Wednesdays (is that breaking the IVth commandment?[:P] Maybe God has cursed the organ!) I do not yet drive by myself, and church is 30 minutes away from home, so it's not like I can just pop over to work on stuff. Moreover, people are very enthusiastic for fellowship and often arrive 30-45 minutes before the service to talk (loudly) in the sanctuary. I am the oldest in a very large family, so we can't really leave any earlier than we do. </p>
I did not get to adjust anything on Wednesday for the above reasons. I checked the Festival Trumpet and it sounded like the tone was messed up too-it was so quiet it was hard to tell. I saw that all the lights were lit though. If I get to it, I'll look into it on Sunday. </p>
Well, if the sound of the Festival Trumpet is messed up and it is too quiet, that does sound as if some of the card rows are not being read properly. If that is the case, perhaps a thorough cleaning (as has been suggested) would clear things up. (Let's hope so.) One thing to check would be that all the lamps (except for row 8) are lined up in a straight line across the array; especially check the lamp you replaced to be sure that it is lined up with all the rest. (The row 8 lamp and its hole are located 1/2 a column width offset, which was explained by the guy who made the digital modification to his reader. Looking from the front, the row 8 lamp is second from the left.)</P>
I'm astonished that someone had to drill to use the Harrison Labs LED kit. T-1 LED's fit the holes just fine.</p>
I used the LED-83 from AllElectronics when I did mine. Put a resistor of about 200 ohms in series with it. It's easier to make a replacement for the whole little board that holds the lamps out of a bit of scrap perfboard. The spacing comes out perfect if you install every other LED diagonally. Click through the pictures at my blog and pull "All Sizes" from the Flickr pages to get an idea of the layout. The big daughter-board didn't fit, and I wound up cutting it in half and joining the halves with a piece of ribbon cable as you can see on the following post, but the first version gives a better view of the perfboard layout.
</p>
Enlarging the holes in the reader is not a good idea. One purpose the holes serve is to shadow adjacent card holes, so you don't have lamp #2 shining through hole #3 to illuminate detector #4.</p>
I can't see any way that a blocked hole could give a big decrease in volume without making a big flue like the Rohrflöte sound like a thin reed. But I can't think of anything else, really, because as David pointed out, the sounds are mixed digitally, so there's no mixer board to adjust for this (The Voix Céleste and the 16- and 32-foot stops are exceptions, but all the stops 8-foot and higher are digital.) If the volume is really low, my first guess is that it's the row-6 (third from the left, there's a gap at row 7) lamp that's bad.</p>
The row-12 sensor tells the reader that there's a card in the slot. If that lamp goes out, it looks as if a card is there all the time - and it's the act of inserting a card that causes the circuitry to begin reading. So without it, you can push cards in and out all day long and nothing will happen.
For example, I have an image of a "Cornet V" card that another member sent me and the Hollerith code in those columns decodes as "R18.0 S00F9194". The "R18.0" might refer to that being the 18th revision, or maybe the 18th release (production run?); the rest may be a key to the stop name in a table, or just an Allen part number.[/quote]</p>
The 18.0 is a scaling factor. It's roughly a measure of the volume of the stop. R indicates that the stop has been rescaled, the base stop has a blank instead of the R.
</p>
I never figured out what the S is. Some cards have an M there instead.</p>
The 00 is a version number.</p>
The F indicates that your Cornet V is a flue stop. D would be a diapason, S a string, R a reed, P a percussion, M a mixture. But they're not at all consistent, a lot appear to be miscoded.
</p>
The next digit is the pitch 1=8 foot, 2=4 foot, 3=2 2/3 (nasard), 4=2 foot, 5=1 3/5 (tierce), 6=1 1/3 (octave tierce), 7=1 1/7 (septième dissonant), 8=1 foot, 9=higher stops, mixtures, mutations with indeterminate pitch.</p>
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