Weak note

[ChoppedTop]

I am working through a few faults with my M100.
Today i set about finding why some notes are not playing all harmonics. With the aid of the service manual i traced the fault to #72 tonewheel.
i checked for broken wires shorted cap etc and all was ok. With a key held down by a lead, I then released the magnet and steadily pushed it further into the tonewheel until i heard it contact. There was also a very faint sound of the missing harmonic. I pulled the magnet back a little and now i have a very very quiet note.
So...what are my options? To me, its looking like i need a replacement magnet(and assembly?) but where can i get one? Can anyone help me out with a spare?
2nd fault is the 4th drawbar on the lower. I've buzzed out the yellow wire everywhere inc plugs matching transformer switches and drawbar bussbar. I cannot find the disconnect. I'd really like to fix this but i'm stuck. I guess i'll be taking apart the lower manual soon!!!

[tpappano]

Have you checked to be absolutely sure that none of the three fine gauge enameled filter wires are broken or cold-soldered? (don't ask me how I know how easy those wires are to break) I'd be surprised if the pickup itself was not working. To test the tg outputs you can connect a piece of wire to one of the drawbars, which must be pulled at least part way out, and use this wire as a 'signal tracer'. My pic is from a M3, but I think yours probably looks the same. In the picture the yellow wire connected at the right rear of the filter is from the pickup. Touch your 'signal tracer' wire to it and see if you have a tone. The level directly from the pickup would normally be a little lower than from from the filter output terminal (front left). Another thing, the pickup position greatly affects the output, so when you pulled it back you could have pulled it back too far.

[ChoppedTop]

I've double checked the 4 filter wires and they are all ok. The cap is a bit difficult to test but i can see it charges and discharges so i reflowed the solder on all the tags. Next, I linked a test lead between the drawbar and the yellow wire on the pick up and it is slightly louder but not by much. I then repositioned the magnet so its almost touching the tw(cannot adjust it any closer). No difference. This pickup is definately weak. Not sure what to do next :0/

[tpappano]

If I were there, I would measure the resistance of the pickup coil (yellow wire) to ground (TG frame) to see if there is a problem with the coil itself. My #72 measures 23 ohms. If you read something similar, perhaps the pickup 'rod' has become demagnetized. One step at time, but I have some Frankenstein-ish thoughts on how it might be restored 8). I would really check the capacitor- if it was too low in capacitance you could have low to zero output from the filter.

edit: more diagnostic blather
When doing the "test lead-drawbar" test compare #72 to #71 and #73 and confirm that #72 truly sucks compared to the others. Basically prove the test procedure is valid 8)

[ChoppedTop]

Ok will do some more testing. Got a busy weekend so i'll be back on it early next week. Many thanks Tom

[ChoppedTop]

Not having the 4th harmonic was bugging me.

I have looked for a broken wire from the drawbar through the manual plug to the matching transformer. The only place left for me to look is the lower manual. so i started dismantling the hammond again. I quite inquisitive to see inside it anyway. The manual was remarkably clean inside and there, staring at me was the broken wire. It became disconnected because the gland wasn't retaining the wires so they got pulled and the yellow one broke off the bussbar. Easy fix and i buttoned it up again.

I also discovered that the loom connections to the tags aren't very good. I think the solder has deteriorated on a few wires because i found one very loose. I reflowed about 3 or 4.
This has got me thinking about doing a lower manual mod and fixing connections as i go. (The weak note #72 pickup problem i'll deal with another day)

I'm not sure how to go about it. I've looked at a few mods on youtube, one shows the loom being extended, moved up 12 connections and jumpers wires running back to the vacant tags. Another i looked at had jumper wires running back for the whole loom? is that correct? which is the best way?

[Pipeorganbuilder]

Good to hear that you were able to find the broken yellow wire so easy. Sometimes they can be difficult to find. I like the idea of reflowing the solder on suspect terminals. This can make many problems disappear. Best of luck on your mods.

Michael

[Jaim]

Weak Tone - make sure that the pickup coil rod set screw isn't corroded and tight.

Lower manual octave drop. One method is to cut another slot to route the cable harness closer to the upper end of the manual. The last one I did for a friend was to extend the harness. I removed the upper octave connections and shrink wrapped the ends. Then one by one I extended the wires moving up an octave. Tedious - but worked well.

Jim

[ChoppedTop]

Finally finished the lower manual. While it was out i extracted the nine bussbars for cleaning. I'm glad i did. They were extremely tarnished and dirty, so i gently rubbed them over some scotchbrite and then wiped them over with some gunwash thinners. There were 2 bussbar that looked as if somebody had bent them with a screwdriver. I figured this was done on purpose to solve a contact problem(i can't imagine this was a factory fix!!). Once straightened all were inserted carefully and i checked all contacts for movement. After bunching all contact together and checking no contacts were making when they shouldnt be. I finally assembled the whole thing and did the lower octave mod. Yes....very tedious extending the loom but the results were well worth it. I'm really pleased how it sounds and all contacts are working perfectly.
The upper really needs doing now. The perc is so noisey. I'll do it sometime next week but probably not going to bother with any foldback mods.
Update later. Thanx
edit:forgot to say...i got the foam out too

[ChoppedTop]

Good to hear that you were able to find the broken yellow wire so easy. Sometimes they can be difficult to find. I like the idea of reflowing the solder on suspect terminals. This can make many problems disappear. Best of luck on your mods.

Michael

Yes, there was nowhere else it could have been tbh.
i guess it broke when i was shifting the bussbar to clear the many bad connections.

[jphilli81]

If I may add to this "Weak Tone" thread, I also have a week tone #54 on my 1974 C3. I have reflowed all of the tags to no avail. I was in the process of reaching into the TG with my backup iron to reflow the connection at the coil (using an endoscopic camera) when Murphy's Law kicked in and the iron died. But in my failed attempt, i happened to ground the upper coil tag to the chassis. This made the tone strong again. I have since alligator clipped the pickup side of the filter to ground alleviating the issue just enough to satiate my perfectionism. My question to the group becomes about the coil and where it should be grounded. The manual shows that there is a ground tag below the coil which I will never get to without removing the TG. Am I causing any harm to the coil with this rigged solution?

[Jaim]

The pickup coil is grounded through the pickup rod and the set screw. Your temp fix won't hurt anything. Which tone number?
Jim

[jphilli81]

It's tone #54. This was the last missing tone in a very oxidized organ. I am under the impression that the tone could still be stronger if properly tended to, but I have already adjusted the pickup as far in as I could. Given all of this, do you think will reflowing the tag on the coil yield any better result?