Allen 225-RTC Repair

[Larason2]

I was blessed to be able to find recently this Allen 225-RTC. It started not functioning as well as it should have, and the small rural church it was in was unable to afford to repair it. It is a MOS-2 unit. It came with 4 HC12 speakers.

I was told that the pedalboard, crescendo pedal, and many of the stops no longer work. Once I got it home, I examined it in detail, please find the pictures below. I found that the foam on all of the drivers was disintegrating, so I ordered the replacement surrounds from parts express, and I'm working on getting them all re-foamed (the 15 inch drivers are done, just have to finish the midranges).

I won't be able to test the organ until the speakers are ready, but I found a few issues I was hoping I could get some advice on.

One is that some of the pins on the analog crescendo pedal controller are bent, and when it moves it squeaks a lot. My thought is that I can just disassemble the crescendo pedal assembly, bend the pins back, then lubricate everything with WD-40. Any tips from someone who has done this before?

The other is that I found two Ni-MH batteries rolling around the upper half of the organ. I looked around, but I couldn't tell where they may have come from. They look like they were once soldered to something, but have since rolled loose. Any idea what these were previously attached to?

I bought the Midi Boutique HWCE2 board with the SM8x8 spreader boards, initially thinking that I might have to gut it. However, after working on it for some time, I'm hoping that I won't have to gut it, since the circuits look like they are in pretty good shape over all. I know I won't be able to solder the SM8x8 to the existing contacts and have them still work, so I am thinking of making my own matrixing boards using pad board, ordering the same connectors as Midi-Boutique off Mouser. Any advice for doing this? I looked into the Midi Boutique 64x1 adapters, but they are too expensive at 50 Euros each. If I do make my own matrix boards, does anyone foresee any problems with the Allen's operation if I solder them directly to the Allen switches?

The final puzzle is how can I add a headphone amp in the output chain from the Allen? It has the amp as you see in the pictures, but generally my wife has me practice with headphones on. I know that many of you have put in a headphone amp, but I was wondering if there were any recommendations of which one to get, and how to hook it up!

I do not have a schematic for the organ, but I will look into getting one if I need one. I will upload more photos once I have my gallery approved. Thanks everyone for your help!

[you795a]

Just to let you know, the Amp is not original to the organ. That amp is an M-5 amp. Those came out in the late 1990's.and were manufactured until around 2012. I'd be curious as to how it is wired in the organ. It is a good amp though and would be line level input.

[myorgan]

One is that some of the pins on the analog crescendo pedal controller are bent, and when it moves it squeaks a lot. My thought is that I can just disassemble the crescendo pedal assembly, bend the pins back, then lubricate everything with WD-40. Any tips from someone who has done this before?

Larason2,

It was common for people to customize their Crescendo pedals by bending the contact wire for an undesired stop so it would not engage when the pedal was pushed. They may not have wanted a Mixture, a Mutation, a Reed, or something else they removed from the Crescendo sequence. You may be able to figure out what each of the wires engaged by turning on the organ, and bending individual wires to make contact with the roller, then match the stop with what you heard.

The other is that I found two Ni-MH batteries rolling around the upper half of the organ. I looked around, but I couldn't tell where they may have come from. They look like they were once soldered to something, but have since rolled loose. Any idea what these were previously attached to?

The batteries probably were soldered to the capture action board. Check behind the panel, and see if the capture action board has a place for the batteries. If you're lucky, the batteries you found have been removed from the board, and there should be wires connected in its place, which lead to a battery box elsewhere on the organ (i.e. floor, or the shelf under the keyboards). That is a recommended repair for those battery replacements.

Hope this helps.

Michael

[Silken Path]

I imagine that crescendo roller was the victim of someone throwing rolled up cable bundles in there and dragging them out. I think you can disconnect the roller, rotate it slightly so that the wood is under the pins, and then carefully push the wires back into position.

Nice clean organ. Congratulations on obtaining it.

[Larason2]

Thanks everyone on your feedback, much appreciated!

That's interesting that it is a later model amp than the organ or the speakers. I was told that this organ was purchased from the Allen dealer in Winnipeg, and since the midranges had already been refoamed at least once, it may have been a refurbished model. They may have replaced the amp with a newer model prior to sale. I've attached a few more photos of the amp, with the wiring labels more visible. The amp wiring looks pretty straight forward, with connectors on the top for each channel and ground, but what I don't understand is the circuit board that it is wired to, which has a lot of inputs, including multiple coaxial inputs. I've attached a picture. The amp has a diagram for volume control, but I'm not sure how I would use it. Maybe it refers to trim pots inside the amplifier case?

Thanks Michael and Silken Path for the feedback on the crescendo roller. I'll try rotating the roller, and seeing if this gives me enough leeway to bend the pins back to where they need to be.

Thanks Michael also for the feedback on the batteries. I'll take picture of more of the upper capture boards, but I fear that there isn't another battery box in the organ. If I have pictures of the boards, could you tell me where to hook up another battery box if I purchase one?

For the headphone amp, I purchased this Yamaha mixer: https://www.long-mcquade.com/43487/P...ries-Mixer.htm. I plan to wire the input to the amp to 3 pin DIN connectors, then wire the output from the mixer back to the amp inputs. At least then I will be able to play it with headphones! The mixer was relatively inexpensive, and I have used it before, so I know it is reliable.

[you795a]

I might be wrong here but I am wondering if that board in photo 1 is to bring the audio from the cage boards to line level and that the two red plugs with the white shielded cable goes to the input of the amp. On the amp on the top left, there are two holes. If you use a small straight edge screw driver you can adjust the pots that are in those holes. Just be careful because those pots do break easily. They are small blue and white pots.

[myorgan]

Looks like it to me, You795a.

As we know the MOS-2 used different, non-line-levels than an ADC or MDS organ would use. Therefore, in order to have a newer amplifier in an older organ, some conversion of the signal needed to take place.

Michael

[Larason2]

I still can't get the gallery to work, so I just posted another post. I'll post more photos of the top dissasembled when I have them.

[Admin]

Uploads to the Galley are moderated. Allow 24 hours for pictures to be available there.

[myorgan]

It looks like your last photo above shows the combination action board. Assuming the board is correctly oriented, you'll see two wires coming off the board in the lower, right-hand corner. That is where the batteries would have been connected. Should you choose to re-connect them, be aware the polarity should probably be advised on the batteries. I may have that information in documentation here-somewhere.

Michael

[Larason2]

Thanks to everyone for their advice and congratulations!

Thanks You795a for the tips about the amplifier. I have finally finished all of the refoaming, and next time I am at the organ I am excited to try it out! If the speakers are too loud, then I will carefully lower the amplifier volume as you suggest, to avoid any problems with the neighbours. The previous owners told me that they had turned the speakers against the walls because they found them too loud! That makes sense that the other audio board brings the organ output to line level. That is very beneficial, because line level makes it a lot easier to interface with other equipment.

Thanks Michael for your advice about the battery. Whoever worked on it last was very kind, as they wrote the battery polarity on the board! I have ordered the appropriate battery cases, and I will attach them to the floor of the upper section, and wire the wires to the appropriate spots on the capture board you mentioned. Looking at other forum posts, I read that there is also a second battery in the lower segment of the organ, in one of the "cages" would you happen to know where about that battery would be, and how to check it/change it? I want to pre-empt some of the common problems if possible.

I took a few more photos of the upper section, in case anyone is interested, or it helps. I'll report back once I've done some more testing. Thanks everyone again.

[Larason2]

A few more photos.

[Larason2]

Finally got to test it out today! The HC-12's look great with the new foam surrounds from Part's Express. I found they all fit beautifully. Gluing them was time consuming, but very gratifying. I found the 15" drivers were a bit trickier than the midranges, but all in all a very satisfying project, and they sound great.

Firing the organ up, I found that the following stops did not play:

Swell: Gemshorn 8, Coppel 4, Nasat 2 2/3, Blockflote 2, Terz 1 3/5, Sifflote 1, Contra Fagotto 16.

Great: Quintaten 16, Prinzipal 8, Octav 4, Waldflote 2.

I found that none of the pedal tabs work, but pedals still work if coupled to great or swell. For the HC12's, I found that only channel 1 was sounding. The capture system didn't work, but I have yet to hook up the batteries, so I will report back when that is done. The transposer, percussion, and tremulant all work beautifully. What I couldn't determine whether or not it is working is the “delay.” When I selected that, I didn't notice any change in the sound, but maybe I'm not looking for the right thing. The Crescendo worked, however the stops controlled by the bent pins did not light up, as expected, and the stops that don't sound anyway also didn't sound.

I had trouble using the card reader, so I am going to see if I can find a troubleshooting topic on the forum for it. To start with, the card didn't insert fully the whole way. I'm going to dissasemble the top part of the organ again to see if there is a mechanical issue inside the reader. For the 4 alterable stops, #1 had a reed programmed to it of some sort, which sounded fine. However 2-4 also sounded like a reed, but very quiet.

All in all, based on what I have read from this forum and given the list of symptoms, I believe that one of the 2 computers isn't working. My plan so far is to try to take out the boards and clean the contacts. I have had trouble finding Caig De-Oxit in Canada, however. Have any Canadian forum members know where to buy it, or know of an alternative? I will also try switching around boards to see if I can isolate which board it might be. The boards themselves look to be in pretty good condition. Any other thoughts on how to go about fixing it?

I have had to resist the urge to gut it. If I gut it, I know I could get it midified faster, but then I know I will regret it. I like being able to just turn it on and get sound out of it, I think the Allen sounds are interesting/nice to play, and I like the idea of the card reader. I also know that it will make it more desirable for the next owner if everything works. I'm a bit sad there are no Celestes on the organ, I understand this is one of the big selling points of the MOS-2 series! The stops that do play sound quite good, but I have to be a bit creative with registration since so many are not working. I didn't find that the HC-12's were too loud at all. However, only two of them made sound, so I probably didn't get the full effect!

The other topic occupying my mind is how to get the MIDI set up? I know with the HWCE2 and the SM8x8 boards, if I just solder them to the key switches, both of them will probably stop working. Unfortunately this organ has a 6x11 matrix, and the HWCE2 boards have an 8x8 matrix. Even if I get the Keymux64 boards, the common ground will probably interfere with the function of the Allen. I have thought of getting mechanical or solid state relays for the key switches, and while these would work, they would be slow and out of my budget! The alternative I have thought of is using transistors to make a kind of relay. For instance:

https://www.mouser.ca/ProductDetail/...vj%2FsIQ%3D%3D

My thought is to wire the Allen switches from the ground side to the gate of the MOSFET, then wire the live pin of the SM8x8 to the source, and the ground side to the drain. In theory this should work, but I'm worried that the board will not be able to supply enough power to run the MOSFET (since they are power dependent). The HWCE2 has two power pins to help run the Keymux64 boards, so I am thinking I will just have to find the right resistor, and connect these also to the sources on the transistors. I would then also connect the ground to the drain side.

For those with more electrical engineering experience, does this sound like it would work? Are there any foreseeable problems I should think about? I wasn't able to find any other similar projects on the forum. I don't have any relevant education for electrical engineering, so I'm working solely on experience and stuff I have picked up along the way on the internet or with the help of friends. I know or can measure the voltages of the boards, but I think it would be very difficult find the amperages with my inexpensive multimeter. I'm thinking of posting the design on “Electrical Engineering Stack Exchange,” and also emailing my uncle, who is an electrical engineer, and a friend of mine who is an engineer for help, once I am able to measure and record the voltages.

Thanks everyone for any advice!

[myorgan]

Finally got to test it out today! The HC-12's look great with the new foam surrounds from Part's Express. I found they all fit beautifully. Gluing them was time consuming, but very gratifying. I found the 15" drivers were a bit trickier than the midranges, but all in all a very satisfying project, and they sound great.

Larason2,

Great to hear you got your speakers re-surrounded, and they sound good.

What I couldn't determine whether or not it is working is the “delay.” When I selected that, I didn't notice any change in the sound, but maybe I'm not looking for the right thing. The Crescendo worked, however the stops controlled by the bent pins did not light up, as expected, and the stops that don't sound anyway also didn't sound.

For the Delay to work, you will need to have all the computers working. You will probably "feel" the effect more than "hear" the effect. It is based on the principle that within a pipe organ chest, some of the pipes in the back of the chest can be up to 10'-20' away from those at the front of the chest. Therefore, Allen's Delay stop attempts to re-create that effect. That's the best explanation I can give.

I'm a bit confused when you say the "stops controlled by the bent pins did not light up." On the 225-RTC, I wasn't aware the stops engaged by the Crescendo lit up at all. Could you explain a bit more?

I had trouble using the card reader, so I am going to see if I can find a troubleshooting topic on the forum for it. To start with, the card didn't insert fully the whole way. I'm going to dissasemble the top part of the organ again to see if there is a mechanical issue inside the reader. For the 4 alterable stops, #1 had a reed programmed to it of some sort, which sounded fine. However 2-4 also sounded like a reed, but very quiet.

For a photo of what the card reader should look like, you can see this photo in my Gallery: https://organforum.com/gallery/displ...um=36&pid=1232. The pattern, looking from the back, should be: 1 light/Space/7 lights/Space/2 lights. In my photo you can see one bulb is out. Alternately, looking from the front, the pattern should be 2 lights/Space/7 lights/Space/1 light.

If the card doesn't go in all the way in, you can check the feed path for obstructions by looking at it as it feeds from the back. Alternately, you can look through the front of the slot to see if you can find an obstruction that way as well. All it takes is one kid (or an ignorant adult) to shove a pencil in the slot, or to rip off part of a card inside the reader. BTW, on MOS organs, almost all mis-read cards will have some sort of a reed sound. In college, I would take my scheduling cards and put them in our auditorium organ, and was always disappointed it always sounded like reeds.

Hope this all helps. Congratulations on all the work you've done so far.

Michael

[davidecasteel]

MOS organ card readers rely on a pattern of 8 and 9 punches to gate the binary data into the register, which holds 16 values. If any of those pairs of 8 and 9 punches are missing, the data in that column does not get added into the register, which will then put the next gated value in that position. Misread cards usually have fewer than 16 values in the register, which has zero values to fill it out.. This produces a waveform with a strong 8' pitch and a limited series of upper harmonics, producing a reed-like sound. Many punched cards (that aren't Tone Cards) will have at least one pairing of 8 and 9 values that get read, so will produce some kind of sound. You can get a similar result by only pushing a Tone Card partway in and pulling it out.

[jbird604]

Congratulations on getting it working to some extent! The 225 has only "one" computer though, not two. Only the model 505 and up in the MOS2 line have dual computers. What you have is one computer with two outputs, one called "main" and the other called "flute." (The names do not strictly correspond to which stops they produce though, as some flute stops are in the main channel, and some non-flute stops are in the flute channel.)

I'd guess that your "flute" channel is dead, and that would agree with the fact that all your pedal division stops are dead. All pedal stops are in the flute channel on standard MOS and MOS2 organs. (Not necessarily true on the larger models with multiple computers, but this is the case on the 225.) You'll have to do some troubleshooting to figure out why the flute channel is dead. Could be that the amplifier or that "pre-amp" (or whatever it is ahead of the amp input) is dead in one channel. Or there could be a cable off somewhere in the audio path from the DAC board to the amp. Or something disconnected or improperly hooked up between the amp and the speakers. Worst case could be a bad MOS board or DAC board, though that is less likely.

Pull the RCA plugs off the DAC board, one at a time, and touch the center pin with a finger. You should hear hum in the appropriate speakers, if the audio system is intact from there all the way to the speakers for that channel. If there is no hum, something is wrong in the audio path.

The capture action might not be working for several reasons. Check the capture power supply unit to make sure the switch (actually a circuit breaker) on the front panel of the assembly is not in the "off" position. Try the cancel piston. If you put all the tabs down, then press cancel, they should all go up. If they don't, the capture power supply is possibly dead. To make sure that the problem is not in the capture memory board, you can remove all the connectors from that board, then power up the organ and try the cancel piston again. if it will not pull the stops up with those plugs removed, the problem is definitely in the power supply.

[Larason2]

Thanks John and Michael for your replies! That is very helpful.

Sorry Michael I was a bit vague about the crescendo. My model has three lights that roughly indicate the crescendo stage above the power switch. When I go from min to max on the crescendo pedal, the first and last light light up, but not the middle light on the indicator. In my haste to try out the organ, I didn't bend the pins back on the crescendo yet, so that is probably why. Could also be a burnt out light, but I hope not! Thanks for your explanations about the delay and the card reader. Very optimistic I'll be able to get the organ running soon!

Thanks John for your detailed explanation about troubleshooting. That's good that there is only one computer! It would be nice to have two, however it sounds like it might be easier to get it running this way! I will try the steps you suggested and report back.

Thanks again for the help! I found a source for Deoxit, but instead of Caig, the brand is Hosa here in Canada. I found it at a local music store, Long & Mcquade. Cheers!

[you795a]

The crescendo light could be a burned out LED but highly unlikely. It could be a broken wire connection between the wire and a lead from the LED. The wires should be tack soldered to the leads of the LED. There could be a piece of "spaghetti" covering the connections. Just slide the "spaghetti" down the wire and you should be able to see the solder connection.

[you795a]

I'm not sure where the LEDs activate but what I am thinking is that a wire may have broken off at the LED itself under the metal plate on the keycheek box next to the keyboards.

[Admin]

The crescendo indicator lights are controlled by contacts to the crescendo roller the same as the stops. Both the contacts for the lights and stops are sequentially shorted to ground as the roller is rotated and the crescendo opened. The crescendo contacts for the stops are in parallel with the stop controls.

As Larason2 has stated

I didn't bend the pins back on the crescendo yet, so that is probably why.

this is the most likely cause of the problem.

[myorgan]

Thank you, Admin. That answered the specific question I had. Of course, Allen changed the crescendo method in the ADC era and following, but it's good to know how they worked in the MOS era.

Michael

[Larason2]

I'm happy to report success! Today I tried out the RCA cable test that John suggested, and I heard a nice buzz from each one, meaning that the downstream audio is working as expected. After that, I took out each circuit board, and cleaned the board contacts and headers with Deoxit, then replaced them. I also disassembled the crescendo pedal mechanism. I also found that the wires also needed some Deoxit! I bent all the wires in the reverse direction to apply Deoxit, then used a small screwdriver and the blunt edge of a hobby knife to bend them back where they were supposed to be. I tried it out, and the missing voices and the crescendo pedal were back! The three crescendo lights all light up now, so that confirms what Admin's post suggested. Thanks everyone for your help - very happy about the progress!

There are still a few more things to sort out. I tried to get the capture action working, but the two batteries that I found rolling around the upper part of the console were both dead. Is it possible that the console would charge them if I leave them connected with the organ on for long enough? (they are NiMH, after all). I'm planning on just buying some replacements if I can find any. I suspect it's not a good idea to just replace them with 2 AA's. I also deoxed the main capture board while I was at it. I wired a new set of wires to the contacts on the board to long wires, and I just got the new battery cases today, so I will wire them in sometime in the near future.

Strangely regarding the card reader, the card stops when it hits the metal enclosure as you see in the pictures. I didn't find a broken card or pencil, or anything like that in the slot. My thoughts are either the metal plate is somehow in the wrong position, or there is some other problem (do the cards insert all the way normally?). If you see the pictures, it seems as though one of the bulbs is burnt out (#12?). I'm thinking of ordering one of the LED kits, as that seems easier than having to order replacement bulbs, then dealing with the very fine contacts on the existing bulbs.

Overall however, very happy with the results. I measured the voltages and amperages for the MIDI boutique board, including the Power T output, and one of the Allen matrix contacts. I think the transistor mechanism would work, however it might be prohibitively expensive to buy enough resistors, given that the Power T is 0.8 amps and 5v. There wasn't enough amperage from both boards combined to operate the transistors, unfortunately. I would also have to hand solder almost 500 resistors and almost 300 transistors! In my search for a better way to do it, I decided that instead of the Midi boutique boards, what I might do is buy a few Arduino Nano Every's (I already have one I was planning for another project that I have decided I no longer need), and wire the existing 6x11 matrix to contacts on the Arduinos with diodes. I would then program them to daisy chain the MIDI, then have one of them for MIDI output. Given I will still have pins left over, I could also wire the expression pedals that way. I will save the Midi Boutique boards for another project!

So again, thanks for all the help. It's good to hear it live again! I will post more pictures as I progress further down the road.

[myorgan]

You describe a properly working card reader with the exception of the lights. Lights 2, 8, and 12 are burned out on your card reader. That said, however, your first picture shows the card fed all the way in the card reader slot. To program a card, you would put the card into the card reader as far as shown in the first photo, and then withdraw it immediately after it stops. IIRC, the programming takes place when the card is withdrawn.

Hope that helps.

Michael

[Larason2]

Hello everyone,

Continuing to make some progress. I bought some new Ni-MH batteries, and wired them to the board and indicated, but unfortunately, the capture action still didn't work. I checked the fuse in the power supply, and it was fine, so I followed John's advice and disconnected all the connectors from the capture control board. None of the tabs went up, so I suspect it is the power supply that is the problem. To be honest, when I first fired it up, I thought that the transformer on the power supply was buzzing quite loud, but I didn't think anything else of it! Come to think of it though, the times I've heard other similar Allen's, I didn't really hear a noticeable buzzing! I knew it was the transformer, but I should have clued in something was going on with that part! I'm a bit leery to work on it, since it has that huge capacitor, so should I just get a replacement 12 V power supply? For instance, would this one work: https://www.rpelectronics.com/psf25-...-12vdc-2a.html

The other issue I have discovered is that Channel 2 is quite a bit quieter than channel 1. I tried voicing them with the volume pots on the amplifier, but I found that even with channel 2 at max volume, it still can't match channel 1 (and channel 1 has volume to spare). Looking at the DAC board, it looks as though there are two pots on there that roughly correspond to channel 1 and 2. Should I try adjusting these, or should I look elsewhere for the source of the problem?

I ordered the LED kit from Harrison labs, I will wire it up and let you guys know how it turned out. I'm also waiting on the Arduinos and related components to midify. Thanks again for all the help!

Regards.