Saving my H112

[Marino]

Hello, first time here on the forum. I am from Belgium so my English is not 100%, sorry for that.
Apparently we don't have an hammond organ forum.

A while ago I bought Hammond H112 serial nr. 4786, for 100 $. The strange thing is that according to a post that I have read, the series numbers below 15000 have foam, mine has felt. Also the amplifier is a AO-70-1-G. I thought that the 'G' only occurred in later models?
The organ has some problems, like most of them. Loose keys, bad drawbar contacts, hum that gets louder as I press the volume pedal, hum when I turn on the celeste, volume drop when the vibrato 'lower and upper on' turns on.
The percussion, like xylophone, does not work on a few notes? I want to tackle the problems one by one and started with the keys and the drawbars, with the help of Bobmann's you tube movies (big help, thanks). The keys are ok again and the drawbars are cleaned and lubricated. They work perfectly. By partially dismantling and assembling the organ, I think something went wrong. Could something have come loose or broken? I do not know, I have done everything as carefully as possible but there is little space.
The problem now is that the lower manual sounds completely different than the upper manual. If you pull the 16' drawbar out (or any other) the lower manual sounds very nasal and much louder. https://youtu.be/szjqcuWMFvk
Does anyone have an idea what can be wrong?
I have the schematics but that is hard to read for me.


I am not an elctro technician but I would still like to save the H112.
I would greatly appreciate that the experienced people here could help me with this. I'm pretty handy, I can solder and I'm looking forward to it.


Does it make sense to create a new post for every problem, or is this better in one post?

Thanks
Regards, Marino

[Jaim]

Make sure the vibrato tabs are off including add vib. Then reevaluate.

Jim

[Marino]

That indeed changes the sound but the nasal sound remains. When I switch on the vibrato there is also a huge volume drop compared to the upper manual?

[Jaim]

When you compare upper to lower, use the same DB settings like 88880000000. With the added harmonics the H series can produce some real nasal tones.

Edit. Make sure the DB's work - the spring metal attaching the DB's to the terminal strip do break. Bb preset on both manuals. Check each DB separately holding down middle C. The absence of a DB will change the tonality.

The vibrato is a separate issue and needs to be TS as such.
Jim

[Marino]

I have set the DB's to 88880000000 but actually it sounds just as nasal than with DB 80000000000 from my first YT video.
This is with 88880000000 https://youtu.be/wjEprW_2keY

Shouldn't the 2 manuals sound the same when drawbars have the same setting?


I have tested the DB's holding down C. None of the DB's has interruption, they all work flawlessly in preset A and B.


Can it be a bad capacitor that affects the sound of the lower manual or maybe the Tonewheel?

Sorry but what do you mean by 'Bb' and 'TS' ?

[Jaim]

Bb preset key. TS = troubleshoot.

With the same registration, the upper and lower should sound the same.

[Marino]

ok, thank you Jim


They don't sound the same so there must be something wrong.


Any idea about the capacitors or tonewheel?

[Jaim]

Any idea about the capacitors or tonewheel?

From the tone wheels, the tones are wired to each manual. When a key is depressed, the tones are on the buss bars which are routed to what ever preset is used. On the Bb preset, tones go to the Drawbars - DB bussbars and to the matching transformers.

The difference between the upper and lower manuals are: manual buss bars, Drawbars and buss bars and matching transformers. The tonewheels are common so that isn't the problem.

Try shifting the manual buss bars.
Possible that the prec circuit is loading down the upper.

Jim

[Jaim]

One other thought - do you understand how the preset panel works? You could listen to a lower preset key. Pick one that has a registration that is fairly standard. Then take the next preset key and wire it to the upper preset panel (you'll have to disconnect a upper to make room) with the same registration. That way you can test the upper matching transformer using the lower manual.

Jim

[Marino]

This morning I turned on the organ and the nasal sound was much less. When I play 1 note you hear a higher pitched tone very quietly. When I play multiple notes, the higher pitched tone comes out louder but certainly not as before. https://youtu.be/EhBH0DcBSN8
Yesterday I moved the organ, don't know if this can have anything to do with it?
I just shifted the buss bars, but I don't have the impression that anything changed. Maybe I have to clean them manually but then I have to take everything apart.


(The organ is now on for about 2 hours and I frequently start to hear loud pop sounds followed bij a crackling sound wich last for about 10 seconds)


The presets; I know that you can create your own presets by swapping the wires on preset panel. I have not done this yet, but I will definitely try today what you advise.


The matching transformers, what does this actually do?
Is that a circuit board embedded in the metal casing of the key bed?


BTW thanks for your help , much appreciated

[Marino]

Update;

I have changed the wires of the lower manual preset E to the upper F in color and order like the lower F.

When I select the upper F there is no sound or should I have taken the G?Is it an in-line / parallel issue?

The lower E has no wires but still has sound?

The nasal sound is back again

I hope I have understood correctly what you meant?


LOWER



UPPER

[Jaim]

The pop sounds can be a capacitor going bad or a dirty tube socket.

The matching transformers (one for upper and one for lower) serve 2 purposes. First is to provide a low impedance load for the tone wheels and second to allow the different registrations. The TWG tones go through the manuals at full volume. When the tone arrives at the matching transformer either via the preset panel or Drawbars, the tap on the transformer sets the level from 0 to 8. The tones are summed in the transformer and sent to the preamp(s).

One other possible cause of the upper and lower difference could be in the preset panels. Make sure you don't have any of the wires touching more than one bar and the screw are tight.

Jim

Jim

[Jaim]

I have changed the wires of the lower manual preset E to the upper F in color and order like the lower F.
When I select the upper F there is no sound or should I have taken the G?Is it an in-line / parallel issue?
The lower E has no wires but still has sound?
The nasal sound is back again
I hope I have understood correctly what you meant?

The intent of the test is to run 2 lower manual presets - one to the lower manual preset bars and one to the upper manual preset bars. This will allow you to test the lower and upper matching transformers. If you wire them with the same registration - they should sound the same.

Jim

[Marino]

Thanks for the info about the matching transformer.


The tube pins is actually the very first thing I have cleaned with deoxit. I didn't dare to inject dioxit into the socket because of the capacitors high voltage. I don't know when they are discharged and maybe it is not safe?
I checked once again that the tubes were firmly in their socket.
I have read that when you tap a tube (or the metal casing) with for example a screwdriver and you get a reverb-like sound, the tube is bad. I have one in the amplifier?


All screws of the preset panels are tight. The wires do not touch any other bar.


The fact that there was no sound on the F preset of the upper manual was because the wires of the lower E were still disconnected. I thought I don't need that preset but apparently everything has to be connected; no loose wires?


All preset now have sound, so upper and lower F should sound the same, which is not at all. https://www.youtube.com/watch?v=yxcuTTi03rw


Does this means that it has nothing to do with the matching transformers?

[Jaim]

It really sounds like some additional harmonics are leaking into the upper. You had stated that you partially disassembled the organ to fix a few issues.

On the right side of the upper and lower preset panels, the wires should go to the drawbar buss bars and matching transformer - compare the color codes of the upper and lower panels especially the color of the wires on the bottom of the upper preset panel.

Jim