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Saving my H112

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  • #16
    I have disconnected all the wires on the right side of the preset panels and cleaned the contacts with deoxit and checked whether the lower and upper preset have the same wire color. That was all correct. Unfortunately nothing changes.


    Can we exclude the matching transformers? I think the upper manual sounds ok, except for the F preset of the lower manual.


    You can see from the picture that I had to tilt everything to get to the lower manuals.

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    Some wires may have been under tension for a moment, some are realy short as you probably know. I have paid attention to it, but a small tug to such a thin wire may cause damage, I think.
    Is it a possibility that a broken wire causes this?


    ---------------------
    I was just trying some things and what you say about the leakage of the harmonics will probably be right. I listened a bit better (maybe you already heard that?) And the nasal tone is indeed caused by a second tone. I have set the drawbars 5 1/3 upper and lower at 8 and when I change manuals, you hear that the 5 1/3 tone remains the same but that a low is added. This is less audible with 16 'as in the first video.
    A video where I hold the keys longer https://youtu.be/Op5XcORtkWY
    Last edited by Marino; 09-08-2018, 11:25 AM.

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    • #17
      Some wires may have been under tension for a moment, some are realy short as you probably know. I have paid attention to it, but a small tug to such a thin wire may cause damage, I think.
      Is it a possibility that a broken wire causes this?
      Possible.

      I was just trying some things and what you say about the leakage of the harmonics will probably be right. I listened a bit better (maybe you already heard that?) And the nasal tone is indeed caused by a second tone. I have set the drawbars 5 1/3 upper and lower at 8 and when I change manuals, you hear that the 5 1/3 tone remains the same but that a low is added.
      That is why I recommended going through the preset panels. I've never looked at the matching transformers in an H1xx series. The schematics suggest that instead of the multi-tap primary used in the 3 series, a resistor ladder type network is used. It is possible the fault lies there as the schematic says .5 Ohms between each input.

      I was hoping someone with H1xx experience in that area would chime in.

      Jim

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      • #18
        Tomorrow or Wednesday I will disassemble the preset panel again to see if there are no broken wires behind it.


        I don't have a diagram of the preset panels and I don't see the matching transformers anywhere.
        Could you tell me where the resistor ladder type network is located on the diagram or in the H112 ?
        Maybe I can measure the resistors?

        I have put the separate schedule sheets back together to 1 large diagram , 4 in total. (I do not know if there are any more schematics?) It is a little more convenient to read (zoom in to read text).
        People who like them in this form can download the file. https://www.dropbox.com/s/kkz5iecbfn...atics.zip?dl=0

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        • #19
          I didn't find anything suspicious behind the preset panel. No broken or clamped wires.
          Is there really no one with electronic knowledge of the hammond? Many models have been built about the same, aren't they?
          Jim was a big help, too bad that the problem has not been solved yet. No matter how, thank you very much Jim!


          The nasal sound and in the meantime the loud uninterrupting pop and crackling sounds. If these 2 problems were solved .....
          Last edited by Marino; 09-13-2018, 09:31 AM.

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          • #20
            Originally posted by Marino View Post
            I didn't find anything suspicious behind the preset panel. No broken or clamped wires.
            Is there really no one with electronic knowledge of the hammond? Many models have been built about the same, aren't they?
            Jim was a big help, too bad that the problem has not been solved yet. No matter how, thank you very much Jim!


            The nasal sound and in the meantime the loud uninterrupting pop and crackling sounds. If these 2 problems were solved .....


            Look at these videos on my YouTube page:
            https://www.youtube.com/user/bobmann...w=0&shelf_id=1
            There are several videos that pertain to the disassembly of the H series.

            The H does not have a matching transformer.

            As far as the crackling noise, the most common cause is a bad connection somewhere.
            If you have not done so, every connector in the organ must be unplugged and treated with DeOxit. There are a lot of connectors, both at the ends of wire harnesses as well as in line with wire harnesses and a few at circuit boards.
            Next, all tubes should be removed and treated by DeOxit on the pins. After doing so, turn the organ on and gently wiggle all the tubes to see if you can make the noise. The tube sockets on H amps are pretty troublesome. One of the pin sockets being loose can cause this problem.
            Your H is very early in the production run, so there are a lot of changes that were made up to serial # 15000. After that serial, all the enhancements has been put in place.

            Here are all the Service Bulletins:
            http://theatreorgans.com/hammond/faq..._bulletins.htm
            Here is the TSB for the crackling problem:
            http://theatreorgans.com/hammond/faq.../V2N4-H100.pdf

            I have fixed a crackling problem by cleaning one of those small pots that are on several of the circuit boards that are along the back of the keyboard. I simply gave them a blast of DeOxit and turned them from stop to stop a few times to wipe away any contamination on the contact surface.
            After that, there could be a resistor or other component somewhere that is going bad. If that is the case, I am unable to help you pinpoint the bad component, this is beyond my capability especially at a distance.

            As far as the "nasal" sound, I am not sure what that means and what advice to offer. It could be some dirty contacts in some of the switches, a problem in one of the amps, or even a bad speaker. Are you sure the speaker cones are all in good shape?

            Regards,

            Bob
            In theory, there is no difference between theory and reality.
            In reality, there is.
            '54 C-2 & Pair of 122 Leslies
            H-324/Series 10 TC
            '35 Model A (Serial# 41) with a 21H
            Look at some of my rescues:
            https://www.flickr.com/photos/58226398@N03/albums

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            • #21
              Hi Bob, thanks for responding.


              I think I've seen all your videos. They helped me tremendously in dismantling. Especially the video where you show how to detach the tab panel, I never would have found that


              No matching transformers? Well, then it is already one thing less to worry about .


              I already cleaned the connectors and tube pins with deoxit. I will certainly try your other tips.


              The service bulletins are great information, which I have not found yet, thanks.


              The small pots, do you mean the blue ones?
              I understand that it is not easy to determine something from a distance, but I am already happy with the tips that can help me.


              The nasal sound came after I disassembled the H and the pop sound came later. Is it a coincidence, I do not know. Perhaps one problem creates the other?
              The speakers sound really good when I play the upper manual.


              This weekend I will work on your tips, thanks again

              Regards, Marino
              Last edited by Marino; 09-13-2018, 05:04 PM.

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              • #22
                The H doesn't have a matching transformer like the multi tap primary the 3 series has. However the block diagram refers to a matching transformer (MT) - I attached a snippet of the schematic which shows a transformer with a resistor ladder type input.

                My theory is the nasal sound is caused by a odd harmonic leaking in. Since the MT is the mix point for the harmonics - that is the logical place to start looking. Where is it? Don't know - however if you look at the right side (column) of the preset panel(s) in the other series of organs it was used to connect the preset panel and drawbar buss bars to the MT. So if you follow the wires from that preset panel column, one should go to the Draw Bar buss bars and the other to the MT.
                Click image for larger version

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                Jim

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                • #23
                  Thanks Jim, the snippet visually gives a better idea where to look.
                  I know you said the resistors are 5 ohms but I read .5 ohm? I wonder if it isn't 0.5 ohm then, or does the dot have a different meaning?

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                  • #24
                    0.5 ohms - more than likely it's resistance wire.

                    Jim

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                    • #25
                      Sorry, I didn't explain it correctly. I mean the .5 ohm on your snippet, is this a half ohm (0,5) or 5?

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                      • #26
                        .5 - see my last reply

                        Jim

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                        • #27
                          right , sorry

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                          • #28
                            Less time than I had wanted this weekend, car problems


                            I have injected the sockets and pots with deoxit and the crackling and popping sound is as good as gone but the hum has increased. The connectors were already treated.
                            I accidentally discovered when you come close to the pre-amp with a screwdriver, the hum increases.
                            So I assume that the pre-amp is the biggest cause for the hum?
                            Some tubes on the amplifier also crack a bit if you wiggle them. It's those that give a reverb-like sound when you tap it

                            As the diagram indicates, the wires from the preset panel go directly to the drawbars.
                            On the picture you see the connection points, can I assume that those blue blocks are the .5 ohm resistors? Can you unsolder this if necessary, they are very small?

                            Marino

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                            • #29
                              Could be - the object of this exercise is to make sure no shorts or dendrites between the terminals. Flush with de-oxite.

                              The H series will hum without the preamp covers installed.

                              Jim

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                              • #30
                                I have removed the tab panel again and found 2 broken contacts, the wires are very short. Can I extend the wires with wires of the same thickness or does this affect the resistance?
                                I hope this will solve the problem.

                                Marino
                                Last edited by Marino; 09-17-2018, 02:16 PM.

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