Help in using non-Allen amps on 900-D

[Guest]

My circa 1972 Allen 900-D, lovingly called The Beast, has severe amp problems. It has 6 channels with a sub channel added off of the flute Gt/Sw. The present amps are the old "50" amps, are very noisy with 60 Hz hum and, according to the local Allen dealer, cannot be rebuilt. I have purchased 4 AudioSource Amp 100 stereo amps for use with The Beast, but have run into problems with the built-in relay system on the organ - it won't turn on using the new amps! The local dealer is unwilling to help me for fear of "degrading the quality" of my 38 year old instrument, which is my practice organ at home, not a public installation. Can anyone give me any tips on what to do make The Beast turn on? There are two cords going from the console to the Allen amp rack - one attaches to a small electronic box which doesn't attach to anything else, the other into the "master" electrical outletwhere all the amps' power cords attach. Any suggestions? By the way, I've used the AudioSource amps before several times,including my previous A-G,and they are quite good even though they are inexpensive. Also, previous to purchasing the new amps, I installed Alesis PicoVerbs in the line before the amps and they work great! And finally, my card reader doesn't work - any suggestions? Help! [:S]

[myorgan]

Re: Help in using non-Allen amps on 900-D



[quote user="WinBand"]And finally, my card reader doesn't work - any suggestions? Help! [:S][/quote]</p>

Is
the card reader not working because of missing lamps, or because it
just doesn't work at all? If it's missing lamps, check my photos
for my photo of an MOS-2 card reader
(http://organforum.com/photos/myorgan...rd-Reader.aspx).
Should be the same pattern of lights you will see, although mine has a
blown bulb in the picture given.</p>

If there are no lights, perhaps
the interface has come loose at the back of the card reader? If
everything seems fine, then a tech will have to answer your question
from there. You've reached the limit of my expertise.</p>

Hope this helps.</p>

Michael</p>

[Guest]

Re: Help in using non-Allen amps on 900-D



Michael,</P>


Thanks for the info. The local Allen tech just told me "it needed work" and would be $100+. I don't recall seeing any lights on, but then I wasn't looking for them either. Of course, since I can't get it to power up at present, I can just look to see. When I do finally get it running, I'll check this out. I know the Harrison Labs in CO has LED light replacements for the card readers, so if I can figure out the problem, maybe I should think about changing them out. But thanks for the suggestions!</P>


Now, does anyone know how I can get The Beast to power up with my new amps??? [:^)]</P>


Bart</P>

[jbird604]

Re: Help in using non-Allen amps on 900-D



Bart,</P>


Just saw your posting, have been vacationing and got back to a busy schedule. Michael called it to my attention.</P>


I've serviced Allen for 25 years and MOS organs are a specialty, so perhaps I can lead you to a solution. Right now it's time for me to get to work, so I'll not say much until tonight. However, I'm puzzled as to how just changing the amps would cause the organ not to power up. Are you saying it won't come on at all? If so, there is some other problem, because the amps have nothing to do with the console coming on.</P>


I'll try to post some more tonight.</P>


John</P>
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[Guest]

Re: Help in using non-Allen amps on 900-D



John,</P>


Thanks SO much for your reply! I'm running out of ideas around here! I plugged the old amps back in as they originally were and the organ still does not power up. The pedal board light comes on, you can hear an initial relay "pop" when turning the key and a few seconds later another relay, but the power light over the key does not come one and there is no output from the organ. </P>


I had a friend of mine who services pipe organs take a look at it and he was kind of baffled too. We see that there are 2 relays close to the power switch and another 1 next to the expression pedals. In following wiring and listeneing, it appears that maybe the one next to the pedals was not activating. All the fuses were checked on both power supplies and "voltage regulators" or whatever those black boxes are called that feed power to the computers.</P>


We also tried to discover the purpose of the "extra" wiring that goes to the amp rack. There is a 4-way AC outlet at the bottom of the organ console just behind the expression pedal that the power supplies and "voltage regulators" plug into. There are also 2 other wires coming out of it, one which goes to the amp rack ACoutlet where all the amps plug inand the other which goest to another little box which connects to nothing else on the amp rack. It has a common and 12-volt labeling where it connects. The one into the amp rack AC outlet has a flat tab locking connector on the faceplate.</P>


I really like this instrument and miss practicing for my church services at home, not to mention having the organ pulled out and wire running everywhere!!! Thanks for helping me get it up and running again!</P>


Bart</P>

[arie v]

Re: Help in using non-Allen amps on 900-D



Hi,</p>

Have you checked voltages (where there is supposed to be voltage) in the organ. A service technician always checks voltages in the organ.</p>

A decent volt meter should be at your ready, when trying to sort out problems in an organ.</p>

AV
</p>

[Guest]

Re: Help in using non-Allen amps on 900-D



Arie,</P>


Thanks so much for responding and getting on the trail of tracking this down!</P>


When my pipe organ repair friend took a look at it, he had a volt meter and prowled around at obvious things. He was finding what he thought was appropriate voltage coming from the AC box at the bottom of the organ, in the power supplies, and a few other places, but not around those relays and the power switch. Since he's really not familiar with Allen (or electronic) organs and I no experience other than changing electircal plugs, that's about as much as I can give you at this point. I'll call him today and see if he remembers anything significant.</P>


Bart</P>

[jbird604]

Re: Help in using non-Allen amps on 900-D



Bart,</P>


A 900 has three totally separate and discrete MOS computer systems. There is almost nothing that is in common to all three! So I'm having a hard time thinking of anything that would make the whole organ silent.</P>


You say that you hear a relay click when you turn on the power, then another relay click a few seconds later. That is what I'd expect, because the first relay is the onedown in the AC distribution box and turns on all the "switched" outlets in response to the low-voltage turn-on signal from the power switch. The second relay is responding to the "delayed" 12-volt that un-mutes the audio signals after the computers have had a few seconds to come up and settle into working condition. So far, so good.</P>


If I were trying to fix this one, I'd first be sure that all the power supply voltages are correct. You have -27 volts (perhaps one terminal "steady" and the other "switched" on some of the supplies), and it is critical. It must be within a half volt or so. You also have +5 volts and -5 volts and they should be fairly close too. The other voltage in the system is an unregulated +12 volts normally produced on a little chassis by itself in the floor. It may actually be as high as 15 or 16 volts, if the power line voltage is high in your area. But if it is absent you won't get anything at all from the organ because it operates the relays -- which we've already determined to be working.</P>


(The 3rd relay you mention, I'm not sure what that would be. Possibly related to a zimbelstern or some other accessory, or connected to the combination action. But in any case it shouldn't be critical to the organ's operation.)</P>


There may also be a separate capture action supply, if that 900 is later production. This supply is not crucial to the organ's operation. It should have a +5 volt output and several other outputs that are triggered by pressing a piston.</P>


After determining that all voltages are present, next thing to do is trace the audio signal. Each of the 3 DAC boards will have two RCA jacks, one marked flute and one marked main. Two of these DAC boards serve the great/swell/pedal and the other one serves the choir manual only. Turning on some stops or depressing the crescendo pedal, then holding down keys, you should find audio signals at the RCA jacks of the DAC boards. You can use a simple audio patch cord from Radio Shack or wherever and connect this output directly to some kind of amplifier and speaker.(Remember that the DAC output of a MOS organ is at a low level, much lower than line level, but it should still be sufficient to drive a modern amp, or perhaps the microphone input of a PA amp.)</P>


If you hear audio at this point, trace the audio cables and see where it is getting interrupted. Perhaps the cabling you mention that runs to theamp rack has some mutes on one end that arenot connected and are failing to "unmute" the audio signal at the amp rack.</P>


If you hear nothing at all from these RCA jacks, there is something keeping the organ from booting up. I'm really at a loss to know what that would be unless you've had a catastrophic lightning strike that knocked out all three computer systems.</P>


I'm thinking that the +12 volt supply is the ONLY thing in the console that is actually common to all 3 systems...... but I can't imagine that it's down since you hear the relays click..... You may have to consult with my good friend Bill Ehrke of Tyson Organ Service if you can't figure this out.</P>


Let me know.</P>


John</P>
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[Guest]

Re: Help in using non-Allen amps on 900-D

John,

Thanks so much for your detailed reply!

When I first got the instrument (and before the old amps started crapping out), I had the local Allen service guy here. He adjusted all the voltages and got everything playing quite nicely. He checked all3 computers, the DACs, the combination action (I discovered that the battery wasn't hooked up last week) and the amps on the first call. He had to repair a capacitor on one of the power supplies, but that was all he had to do besides adjust voltages. The card reader has no lights showing at all. He didn't tell me what the problem might be, but said it would be a minimum of $100 to work on it.

It was playing fine before I disconnected all the old amps and added the new amps. I had inserted some Alesis Picoverb units between the organ and the amps several weeksprior todeciding to get the new amps. The old ampswere becoming very noisy with 60Hz hum. The inserting of the reverb units dida great job in making the organ sound "real". The Allen guy told me the old amps could not be rebuilt (which lead me to believe he wanted me to buy 7 new amps!).

When I disconnected the old amps, I simply went from the Picoverb units to the new amps, which were NOT plugged into the old amp rack AC supply plug, which had a cord coming out of the organ AC distribution box to the amp rack AC distribution box. I also did not have that mystery line that goes from the organ AC distribution box to the little mystery unit on the amp rack. No sound was coming out of the organ even though it was playing before I changed amps.

I've placed a call in to Bill Ehrke about 2 weeks ago, but haven't heard back from him...don't know if he's on vacation or what. If you have an way to contact him more directly than his work voice mail, I'd be glad to have him out to get this problem solved!

In the meantime, I'll try finding an output signal from the DACs as you suggested and see if any signal is getting that far. I sure hope those things didn't go out!!!!

Again, I appreciate so much you taking the time to help me out and I'll let you know what I discover. Also, tell Bill he's needed desperately!

Bart

[jbird604]

Re: Help in using non-Allen amps on 900-D



Bart,</P>


If you've left voicemail for Bill, that's the best you can do. He's probably taken some time off this summer (as most of us do if we can!) and may be behind in answering calls. You might trycalling him in the evening if you haven't done that already.</P>


I still can't imagine what would cause the organ to stop working if you did nothing more than switch the amps out. The mystery line going to the amp rack, if not hooked up to anything, must have been connected to some external accessory at one time in the organ's past, but it shouldn't have anything to do with it now.</P>


Regardless of what the mystery box is, there should be audio at the output jacks of the DAC boards. All muting, expression, and other audio functions are carried out downstream from the DAC boards, so you'll get raw audio at the DAC outputs if you plug an RCA plug into the jack and run it directly to some kind of amp.</P>


It would be some extraordinary catastrophe to wipe out all three MOS systems. If the +12 volt supply is working, you'll get sound out of one or all of the DAC boards.</P>


Since you have the little reverb units in place already, you won't even have to worry about level-matching with the new amps. You can simply boost the output of the reverbs to bring them up to the line level required by modern-day amps (as opposed to the low-level signal that was being fed to the old T-50 amps).</P>


BTW, it's hard to imagine that the old amps couldn't be rebuilt if they only had 60 hertz hum. We used to renovate those quite often just by replacing all the electrolytic capacitors. Now, if any of the germanium transistors are bad, that's another problem. But hum could generally be managed.</P>


But you'll probably get better overall sound with those new amps. I put new ones on a MOS organ a couple of years ago and it really cleaned up the sound, gave it more oomph and body. The T-50 was a good old workhorse of an amp, but a little puny by modern standards.</P>


John</P>
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[Guest]

Re: Help in using non-Allen amps on 900-D



John,</P>


I tried connecting directly to the DAC outputs and got nothing. I know the amps were "hot" because I'd get a pop when plugging in the RCA plug. When I turned on the organ, I heard the 2 different clicks but again the indicator light above the key switch doesn't light up. The pedal lights come on. I hear a slight hum from the power supplies on the back right side of the organ. Next suggestion? [*-)]</P>


I placed another call to Bill Erhke, but haven't heard from him. If you have an email address for him, would you mind dropping him a line? Also, that was interesting info you gave me regarding the present amps. Yes, I think it was the capacitors...sometimes you could tap on them and they'd get much less noisy, but eventually that didn't help.</P>


Again, thanks for your time and patience!</P>


Bart</P>

[jbird604]

Re: Help in using non-Allen amps on 900-D



Bart,</P>


I'mtotally baffled. If I were there I'd probably figure it out in 5 minutes though. Those MOS organs are SO simple.... If you've got -27, -5, and +5, the computer is running and there will be output at the DAC. It would be a one-in-a-million coincidence for all three computers to be down at the same time!</P>


Perhaps the +12 volt supply is down. It does have to be working to activate the relays in all the power supplies that switch the -27 between the "steady" terminal and the "switched" terminal. Check it with your voltmeter and look at the fuse.</P>


It osremotely possible that the "mystery box" is either switching the +12 or that it is pulling the +12 down. Try disconnecting it completely from the system and see what happens. Look inside the box and see if there is a relay. Perhaps it is supposed to be closing and its contacts have become non-conductive for some reason.</P>


One other possibility .... all stop switching is "ground" so the stop rail and crescendo pedal contact strip must be at a solid ground potential. You could use an ohm meter to determine if the stop rail metal is solidly grounded. Have you already determined that there is no sound when the crescendo pedal is engaged?</P>


The only other thing that comes to mind is that you had a lightning strike and it took out some componentin each of the MOS systems. But that would be so rare.</P>


Just be patient with Bill. He is the best in the business and covers a huge territory. Even here in my state where we have far fewer organs we are sometimes weeks behind in returning calls. Church organs get priority treatment too, because when one is down it affects a great many people.</P>


John</P>
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