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Allen ADC-5400 My New (Old) Practice Organ

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    John,

    Thank you for the detailed information. Believe it or not, I actually understand it since you explained it. It's almost like the FAT sector of an old harddrive, or the matrix of a tracker. I have the card back out of the organ, so if I get a chance to try it out tomorrow, I'll let you know how it turns out.

    I love a good mystery!

    Michael
    Way too many organs to list, but I do have 5 Allens:
    • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
    • Lowrey Heritage (DSO-1)
    • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

    Comment


      OK, I no longer love a good mystery.

      I cut some stranded wire so I could add the copper as John suggested, but then had a brilliant idea! Why not swap the two DAC chips to see if the problem moves with the chip missing the 3 legs? The problem stayed where it was and did not switch to the 16A stops as I expected, so I guess that means I no longer have a possible solution. The stops in question worked for a millisecond, then went out.

      So, what is the likelihood one of the voicing pots on the 16AA channel is defective (i.e. gain)? I've never replaced the mini pots and don't know how to check them for where the issue is. How would one check--millivolts or ohms? Would I be helped in any way if I had a schematic of the USTG-6 card, or would that just be more confusing?

      The other thing I haven't mentioned until this point is that in the past, the intermittent issues appear to have been related to temperature. Today, the organ is in the mid-30s, but in the past during the Summer when I've been playing and it goes above 80˚ or 90˚ inside, that can also cause the intermittent issues. I almost hate to ask this question because I know who I'm going to hear from next, but could it be a cap going?

      Michael

      P.S. John, I'm so sorry to hear about your organ's issues today. Could I loan you one? You'll certainly have your hands full for a bit of time!
      Way too many organs to list, but I do have 5 Allens:
      • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
      • Lowrey Heritage (DSO-1)
      • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

      Comment


        The mini pot will have the ohm value stamped on it. You can check the value of the pot. by using a ohm meter across the two outside pins. The inside pin is for the wiper(the variable) part of the pot. Make sure you use solder wick to help wick out the solder from the plated thru holes the pots. pins are mounted in.

        Michael

        Comment


          Michael,

          We were discussing the DAC08 chips elsewhere on the Forum a few weeks ago. They are indeed digital to analog converters, and they are still in production. The two-letter suffix on the part number specifies temperature range and linearity rating, as I recall. Neither is enormously important in your application.

          From your photo, I would say that the short pins are still making contact with the socket, although much would depend on the details of the socket receptacles (how far they are recessed below the plastic, in particular). If swapping in a different chip makes no difference, then the chip you have is likely to be good. I am surprised that these parts are socketed--on my ADC boards, they are soldered in; when I overhaul a board, I do install sockets to avoid stressing the new parts thermally.

          If you want to replace the chip, I can direct you to an appropriate vendor and part number.

          Meanwhile, you have a bank of dead stops, apparently. I would suspect (in order): 1) Bad solder on the FG board. 2) A loose EPROM or socket 3) A dead op-amp in the BTMG filters for that channel. I would try reflowing all of the solder on the board as a first step (maybe time to hire that engineering student?) and then shotgun the op amps and DACs, which cost a few dollars and are easy to change. Beyond these steps, you are looking at methodically replacing all of the chips on the board, which I have done a time or two. It is not quite as bad as it sounds; the big effort is cataloging and ordering the parts, which are not always available from a single source. The only chip that is not available is that infamous S-152 that Walt Greenwood says performs some "basic logic functions." Unless he decides to dish, its function will probably remain a mystery. However, it seems to fail very rarely.

          Comment


            It's too bad that our beloved ADC organs are beginning to show their age. Up to this point in my career, I've not seen many ADC models with intractable problems. Oh, back in the day there were some shipped out of the factory with lousy chips of certain types, and the boards failed early on while still in warranty. And there have been the occasional failures of the power supplies and amps.

            But over the past 20 years about the only board problems I've seen have been cured by "exercising" the pots and cleaning up and lubricating the chip legs and the card-edge sockets. It's been a very long time since I had to order an ADC cage board from Allen, at least since all the bad USEG-1 boards got sorted out. The Allen engineers and assemblers really had their stuff down to a science by the ADC era, and we don't see the kinds of troubles that plagued other organs of similar vintage, like the Conns and Baldwins with the bad soldering.

            So I'm shocked and unsettled to have begun dealing with cage components going bad these days. I've had a couple of USPS-3 units go bad in the last year, and now in my own church's MDS organ. And last year I had to replace an FG-5 board in an early MDS organ. And now it seems that Michael may have a genuinely bad TG-6.

            So, it troubles me, and makes me wonder if we'll have more of this in the coming years. But you know, the old MOS organs just soldier on, don't they! I think many of the MOS and MOS-2 organs may still be standing when everything newer is done for.

            I sure hope you can figure this one out, Michael, as Allen is bound to charge several hundred dollars to exchange your board. Of course if that's what it takes you still have one heck of a bargain organ!
            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!

            https://www.facebook.com/pages/Birds...97551893588434

            Comment


              Old Allen boards are expensive......BUT...... They still have them....Kinda like my old John Deere 40 farm tractor built 1947..... I could still get parts from a John Deere dealer in 2002....They were very "dear"/Deere" then too Sorry bad pun! Point is we must pay for the ability to replace ancient (in the Digital organ world at least) parts kept in stock at some expense by Allen.

              - - - Updated - - -

              John My old 4300 ADC is still going strong. It was built for me in 1987 and I sold it to a local church in 2003. They are quite happy with it although I think it needs the base extra 2 channels plus subwhoofer.
              Rob in Thunder Bay

              Comment


                Originally posted by robmcginn View Post
                John My old 4300 ADC is still going strong. It was built for me in 1987 and I sold it to a local church in 2003. They are quite happy with it although I think it needs the base extra 2 channels plus subwhoofer.
                Rob,

                Different topic, but my 4300 is also doing well, and I have already split the Great/Pedal channels and added a sub. There is more definition of sound on all the involved channels, but it is surprisingly difficult to voice once the channels are separated. I forget if I disconnected the Bass Lift card or not (I suspect I left that one alone).

                Back on topic, I was re-reading this thread, and came across an old post (#85) where I had switched the amplifier channels, and the issue moved from the Choir to the Swell. However, that said, my post wasn't exactly clear which issue it addressed (or both). I had talked about two different issues I didn't realize may have been unrelated at the time: Static coming from the Choir stops, and 1/2 of the Choir speaking intermittently.

                Looking back, it seems to me they may actually be two different issues--the first being solved by John's routine maintenance, and the 2nd possibly being related to something in-between the cage and the speaker (as the DAC chip swap didn't make the issue move). The only things to narrow the issue down would be the possibly bad amplifier channel, and the Trem-III Unit on that channel.

                Unfortunately, I'm quite busy this week with work, rehearsals, and performances, but hopefully I can take some time next week and sort out the issue by narrowing it down to only one device in the chain. I need to do it soon, however, because colder temperatures seem to exacerbate the issue, and it looks like warmer weather is coming soon!

                I'll keep you posted on what I find out. Thank you all for your input (or is that "output?").

                Michael
                Way too many organs to list, but I do have 5 Allens:
                • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                • Lowrey Heritage (DSO-1)
                • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

                Comment


                  Originally posted by myorgan View Post
                  Back on topic, I was re-reading this thread, and came across an old post (#85) where I had switched the amplifier channels, and the issue moved from the Choir to the Swell. However, that said, my post wasn't exactly clear which issue it addressed (or both). I had talked about two different issues I didn't realize may have been unrelated at the time: Static coming from the Choir stops, and 1/2 of the Choir speaking intermittently.
                  Well, I confirmed it. Today I connected the organ, turned it on, and verified the Choir Viole Celeste group of stops were not working. I turned the organ off, switched the inputs between the Choir and Swell on the same (triple) amplifier, and the Choir stop group worked (and the Swell didn't).

                  So, that means the issue I've been having is definitely with the ADC amplifier module for that channel. It just happens to be module #3. I guess I've got some time, but I'll be looking to repair the module I have. I'll be re-reading people's advice about testing modules and the usual culprits that fail, but failing that, I will probably be looking for a new (or spare) ADC module in the next month or two.

                  Thank you so much for all the advice and input here. Now, I just need to get busy and get the amplifier repaired. Thanks everyone.

                  Michael

                  P.S. John, I know you've got your own troubles, but I may be calling on you.
                  Way too many organs to list, but I do have 5 Allens:
                  • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                  • Lowrey Heritage (DSO-1)
                  • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

                  Comment


                    I do have a PILE of old ADC amp modules, but they were all damaged in a catastrophic AC wiring disaster. I might have at least one among them that's good, if you find that you can't fix what you have. Let me know.
                    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!

                    https://www.facebook.com/pages/Birds...97551893588434

                    Comment


                      Originally posted by jbird604 View Post
                      I do have a PILE of old ADC amp modules, but they were all damaged in a catastrophic AC wiring disaster. I might have at least one among them that's good, if you find that you can't fix what you have. Let me know.
                      John,

                      Would you have a schematic and/or set of steps to go through to diagnose the issue with the module? I haven't the first clue where to start. If you have it, you could send that information to my private e-mail address you have on file.

                      Let's handle the rest of this conversation privately, and either you or I could post the information that benefits the Forum when we have come across the troubleshooting process and had it work successfully. I'll start a new thread for the topic as a placeholder.

                      John, thanks for being so willing to help, even in the middle of your own crisis.

                      Michael
                      Way too many organs to list, but I do have 5 Allens:
                      • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                      • Lowrey Heritage (DSO-1)
                      • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

                      Comment


                        Check your email and let me know if you got it.
                        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!

                        https://www.facebook.com/pages/Birds...97551893588434

                        Comment


                          Originally posted by jbird604 View Post
                          Check your email and let me know if you got it.
                          Yep, did. I'll keep y'all in the loop in the other thread as I progress.

                          Michael
                          Way too many organs to list, but I do have 5 Allens:
                          • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                          • Lowrey Heritage (DSO-1)
                          • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

                          Comment


                            Troubleshooting time: I just re-connected the ADC-5400 after a long winter's nap (in garage). It got up to 46˚F today, so I couldn't resist any longer. My it sounds nice with all those celestes!!!

                            I discovered when I reconnected that the Hautbois 8' on the Swell doesn't work–it's the only stop. What do y'all think is the issue:
                            • Cracked reed switch
                            • Disconnected wire somewhere (perhaps a sense wire)
                            • Broken mechanism
                            Where would you all put your money on the potential issue?

                            Michael

                            P.S. If it's the reed switch, what size would be the replacement?
                            P.P.S. Also, John, I never did fix the relays on the Brass Choir and Choir that were crackling. How do you feel about a bit of mail-in work?
                            Way too many organs to list, but I do have 5 Allens:
                            • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                            • Lowrey Heritage (DSO-1)
                            • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

                            Comment


                              I have had my share of reed switches that will not "make" after a long period of use. Sometimes cycling the magnet or tapping on the stop mechanism will coax it back to life, at least temporarily.

                              Comment


                              • myorgan
                                myorgan commented
                                Editing a comment
                                I'll try that. Thanks Don!

                                Michael

                              ADC amp module: I heard this from someone who repairs them; sometimes if you just disassemble the various parts, make sure all contacts are clean, and all the hardware tight as you re-assemble it- that will fix an intermittent problem. At least that's what he did for me.
                              Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

                              Comment


                              • myorgan
                                myorgan commented
                                Editing a comment
                                John,

                                Thanks for the input. You must've read through the entire thread where I thought the crackling was the amplifier. John (jbird604) and I were able to narrow it down to the antiphonal relay and the little white boxes they are in. In fact, I have the Choir stops channeled through the antiphonal because the mains are too crackly. I just had to change the combination action to always include the Choir>Antiphonal to serve for now. I actually performed a concert that way with the Symphony.

                                Michael
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