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Allen ADC Amplifier Module Repair

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  • #46
    Michael's suggestion of a power strip may be your best option. The D-40 amp is no longer available from Allen. The two-channel ADC amplifier could be made to work, but it needs an external relay voltage to unmute the audio inputs. The D-40 has built-in muting and required no external delay circuits, so there would be some engineering required and some other parts to add before the ADC amp would work in that organ.

    Best to get the D-40 amp repaired. It probably only needs the mute relay replaced on channel 2. It is an inexpensive part, but changing it requires technical and soldering skills. If you have a good organ tech, you could have it looked at and have general maintenance done at the same time as the amp repair, thus getting more for your money.

    But it would be ok to put a power strip on the amp and simply turn it off before powering down the 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!

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    • #47
      Originally posted by myorgan View Post
      Lina,

      Welcome to the Forum!

      The "bang" you mention is probably the mute relay failing in the D-40 amplifier you have. The mute relay in the amplifier keeps sound from going to the speakers until a few seconds after the organ is turned on.

      While I'm not sure the ADC Amplifier is a direct replacement for the D-40, I believe it certainly could be used. That said, however, it would probably be too much power for your organ's sound. If you wait until the organ techs weigh in, they can provide definitive answers to your questions.

      Meanwhile, another solution would be to temporarily put the amplifier on a power strip that can be turned on after the organ is turned on. Then, when turning the organ off, you can turn the power strip with the amplifier off before turning the organ off. That should prevent your "bang" for the time being.

      Hope that helps temporarily.

      Michael
      - - - Updated - - -

      Originally posted by jbird604 View Post
      Michael's suggestion of a power strip may be your best option. The D-40 amp is no longer available from Allen. The two-channel ADC amplifier could be made to work, but it needs an external relay voltage to unmute the audio inputs. The D-40 has built-in muting and required no external delay circuits, so there would be some engineering required and some other parts to add before the ADC amp would work in that organ.

      Best to get the D-40 amp repaired. It probably only needs the mute relay replaced on channel 2. It is an inexpensive part, but changing it requires technical and soldering skills. If you have a good organ tech, you could have it looked at and have general maintenance done at the same time as the amp repair, thus getting more for your money.

      But it would be ok to put a power strip on the amp and simply turn it off before powering down the organ.

      Thanks Michael and John,

      Its really helpfull! But I cant find this "mute relay". I dont know how it looks like... Can you upload some photo or description (eg. serial number) ? To have a clue what I need to search for. Then I could try to find it and to ask someone to replace it.
      I checket D-40 for some damaged capacitor or other damaged part (that I could see) on board, but cant see it....

      Thanks for help and advises!
      Lina

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      • #48
        The mute relays are located inside the D-40 amp, under the metal chassis. So you can't see it without taking the amp out of the organ and looking at it from the bottom. They are soldered directly to the circuit board.

        Allen has used more than one style of relay for the mutes, but it's usually a small black rectangular device about 1 or 2 cm wide and maybe 3 or 4 cm long. It is usually a sealed unit with several wire legs coming out of it. Two wires go to the magnet coil on the inside that activates the armature. The other leads go to the contact terminals inside. The unit is wired into the amp so that it shorts out the input signal when the organ is first turned on and instantly when it is turned off. After the organ is powered, in a few seconds the un-mute voltage is sent to the coil, which moves the armature and un-grounds the signal so the amp can sound.

        Here's an example of a miniature relay like this, though Allen's are more commonly rectangular than tubular like this:

        https://express.google.com/u/0/produ...hoC1MUQAvD_BwE
        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!

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        • #49
          Originally posted by jbird604 View Post
          The mute relays are located inside the D-40 amp, under the metal chassis. So you can't see it without taking the amp out of the organ and looking at it from the bottom. They are soldered directly to the circuit board.

          Allen has used more than one style of relay for the mutes, but it's usually a small black rectangular device about 1 or 2 cm wide and maybe 3 or 4 cm long. It is usually a sealed unit with several wire legs coming out of it. Two wires go to the magnet coil on the inside that activates the armature. The other leads go to the contact terminals inside. The unit is wired into the amp so that it shorts out the input signal when the organ is first turned on and instantly when it is turned off. After the organ is powered, in a few seconds the un-mute voltage is sent to the coil, which moves the armature and un-grounds the signal so the amp can sound.

          Here's an example of a miniature relay like this, though Allen's are more commonly rectangular than tubular like this:

          https://express.google.com/u/0/produ...hoC1MUQAvD_BwE
          Click image for larger version

Name:	MuteRelay.jpg
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ID:	606886

          Thanks John! I think these relays are (in the pfoto black rectangulars) HE421B1250. Found in internet official name ir "reed relay" (that is confusing me). But on the board are no other relays. So I assume that one on them (for channel 2) I need to replace. If you could approve that Im on the right direction - I would be more than happy :-)

          Thanks a lot!!!!
          Lina
          Last edited by lina; 12-30-2018, 01:55 PM.

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          • #50
            Yes, those are the relays. And they are indeed "reed" relays (because they use an ordinary reed switch as the armature). If you can replace the one on the bad channel it will probably stop the noise. Good luck!
            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!

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            • #51
              Originally posted by jbird604 View Post
              Yes, those are the relays. And they are indeed "reed" relays (because they use an ordinary reed switch as the armature). If you can replace the one on the bad channel it will probably stop the noise. Good luck!
              John,

              Is it really that easy to replace the mute relay on a D-40 amplifier? I would assume if a person searched for that particular item number on the Internet, manufacturers would vary in quality. Is there a manufacturer you recommend?

              I'm preparing for the possibility one or more mute relays will need to be replaced when I get the ADC-8000 out of storage. Thanks in advance.

              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)
              • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

              Comment


              • #52
                Michael, that Hamlin relay assembly was used in more than one Allen product. The D-40 amp, and also, I think, the "muterel" assembly that was used for muting in MOS organs and early ADC models before the ADC amp design replaced the old S-100 amps.

                The photo you posted in post #7 in this thread show a Hamlin reed relay on the ADC module board, and it may well be the exact same one. At any rate, it's bound to be a very common type that one could get from any number of internet suppliers.

                I'm not sure that every ADC amplifier module uses a Hamlin relay, but if you look at one you will see the relay and can probably find it by googling the part number shown on the relay enclosure.

                Shouldn't be too hard to replace one of these. I can't say for sure if I've ever done it though. There are probably any number of relays out there with about the same specs. You'd need to make sure the coil resistance is about the same, and that the legs are in the same place for ease of mounting right on the pc board. And of course the driving voltage would have to be the same as the original, probably 12 volts, at least in every Allen design that I know about.
                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!

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                • #53
                  I did a little searching for that relay and it seems to be an obsolete Hamlin model--Hamlin is now owned by Littelfuse. Though I couldn't find that exact model number, their PN structure--specifically, the "B" in the model number--suggests it might be a normally closed relay operating on 12 VDC. The NC versions are not as common to find as the NO and the NO/NC versions. Not finding a datasheet referencing the specific PN I don't know if the NO/NC (changeover) type could be substituted directly or with a clipped lead.

                  Anyone wishing to do this repair might do well to call Littelfuse and speak to an application engineer to determine what current model might be a suitable replacement.

                  Comment


                  • #54
                    I have done the research too. All I found is:
                    https://media.digikey.com/pdf/Data%2...PDFs/he400.pdf
                    But this is only for type A and C. I could not find type B...


                    There is a similar part (HE721B1200) on:
                    http://www.farnell.com/datasheets/1633363.pdf But again is not exactly as I search. I could not find other parameters (like A, W, and Ohms) that my reed relay needs.

                    This part is on the Littelfuse companies catalog (page 12):
                    https://www.littelfuse.com/~/media/e...atalog.pdf.pdf

                    Happy new year! And thanks a lot for your help!
                    Lina

                    Comment


                    • #55
                      In the Allen organ dealer parts catalog (which is updated frequently, so I assume it's accurate), the relay is shown as still available, though the part number has changed.

                      The numbers on the illustration of the new Hamlin relay are as follows:
                      HE421B8619 with the four digits 0050 on a separate line underneath.

                      But the Allen catalog says the part number is as follows:
                      B1B12X960GIA

                      I can't find any google hits on either number though.

                      Hamlin apparently no longer exists as a brand name, or else is entirely subsumed under LittleFuse.

                      The Allen catalog does confirm that the same relay is used on the D-40 amp, the ADC amp module, and the old Muterel assembly used with the S-100 amp in MOS and early ADC models.

                      If there is no direct replacement for this relay available, you might have to use some other micro relay with a low-current 12 volt coil. Then use the pins that give you a N.C. connection.

                      Not brain surgery, but it might require more re-engineering that some are comfortable with.

                      Wish I could speak from experience, but I don't recall having to do this yet. I do have an ADC module on a shelf at the shop with a bad mute relay, so I "might" get around to trying to fix it someday, though it's not something I need to do right away.
                      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

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                      • #56
                        Originally posted by jbird604 View Post
                        The Allen catalog does confirm that the same relay is used on the D-40 amp, the ADC amp module, and the old Muterel assembly used with the S-100 amp in MOS and early ADC models.
                        John,

                        Based on the photos included in this thread (Post #7 & #49) where both mute relay part numbers match, would it be a safe assumption that the D-40, S-100, and (at least) early ADC amplifiers used the same relay? Then, based on that assumption, if we found a similar/same NC drop-in replacement for that part, it would be safe to use for all amplifiers?

                        Just a thought.

                        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)
                        • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

                        Comment


                        • #57
                          Yes, Allen used identical relays for the D-40, the Muterel assembly, and in ADC amp modules. If we can locate a currently-available 12 volt reed relay with the correct specs and pin spacing it would be a drop-in replacement for all these applications.

                          It must have a low-current 12 volt coil and the contacts must be Single-Pole-Single-Throw and wired Normally Closed. Here's a pic of a type that MIGHT be the same pin configuration, though I can't find this info on line. And this one doesn't even say if the contacts are Normally Closed or Normally Open.

                          So do NOT order one of these unless you can get more info on it. When I have time, I'll remove a Hamlin relay from an amp module so I can see the pin layout.

                          https://www.radioshack.com/products/...YaAr4wEALw_wcB


                          And here's something that we might have to resort to using. This is definitely spst-nc with low current 12 volt coil and a reed contact. The drawback is that the mounting style is completely different. You'd have to make up a little adapter by using a DIP socket and some short bits of thin wire to pick up the 12 volts from the circuit board, and connect the proper pins of the socket to the signal and ground points on the board. Not rocket science, but does require a bit of soldering and some logical thinking. And you'd want to mount the relay socket to the pc board for safety and neatness. Sounds complicated, but it may be the only way to keep the ADC amps going, if there is no longer a drop-in relay available.

                          https://www.galco.com/buy/NTE-Electr...MaAvqHEALw_wcB
                          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

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                          • #58
                            John,

                            Would any of these work: https://www.mouser.com/Search/Refine...VDC+Reed+Relay ?

                            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)
                            • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

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                            • #59
                              Hard to say, Michael. Would have to compare the pin configurations with the layout on the ADC module's pc board. At least they are all apparently 12 volt coils with spst-nc contacts.

                              Man, some of those are PRICEY though, aren't they! A plain little reed relay shouldn't cost more than a few dollars. Don't know how they can be $50 or $60 or more.
                              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

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                              • #60
                                I was at the shop yesterday and took a close look at the relay on some ADC amp modules. Yes, the pin configuration is the same as some other reed relays I've seen. Three wires come out one end (the two outer wires in that group of three are the coil wires, and the middle wire is one end of the reed switch itself). The other end has only one wire, which is the other end of the reed switch.

                                A great many spst-nc reed relays are available, but some of them have really different pin arrangements, some come in a DIP package or a SIP package, some have too low a coil resistance (would draw too much current through the USCM or MN board, so not suitable for some Allen applications).

                                Here's a relay with a 400 ohm coil that should work. The wires come out the bottom in a SIMILAR arrangement, though slightly offset to one side, judging from the online specs. It might take a minor bit of engineering (bending the wires), but it looks like the closest thing to a drop-in replacement I've found.

                                https://www.mouser.com/ProductDetail...52bTTRlZ99A%3d


                                I don't know why there is such a scarcity of relays that have the exact pin arrangement as the old Hamlin units that Allen used. You'd think that such a simple and useful component would be available from many sources. The world of electronic spare parts is a strange one!

                                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

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