Missing tone

[Guest]

Hello All,

I'm new to this Forum and new to playing a keyboard/organ...bucket list thing you know! So to say the least I'm a beginner. With that said, I just purchased and took delivery of a 1962ish Hammond A100 ($500 eBay "moving special") that most likely has been sitting in storage for quite some time. Slowly waking her up. Got the tonewheel running quietly (it was grinding horribly at first), cleaned up the very grimy keyboard and cabinetry (now looks vintage new), and have been testing out the keys at each drawbar setting. What I discovered is that I lose one key/tone on both the upper and lower manuals at each drawbar including just Percussion turned on with no drawbars. The key is not necessarly the same one with each setting but I figure there must be one thing in common: capacitor, wire, tube, stuck tonewheel, ??? that each setting uses that is causing the problem.

Here is what I found:

Upper manual percussion ON only - Black key B: no tone on the middle C=C4

Both upper and lower manual setting - either white key/Bb or black key B

first drawbar: no tone on C6
second drawbar: no tone on F4
third drawbar: no tone on C5
forth drawbar: no tone on C4
fifth drawbar: no tone on F3
sixth drawbar: no tone on C3
seventh drawbar: no tone on Ab2
eighth drawbar: no tone on F2
ninth drawbar: no tone on C2

What I did discover is it's all the same "tone" that's not playing so I'm guessing stuck tonewheel perhaps? Getting ready to attack the dirty ole electronics with some Deoxit next :)

Any help to troubleshoot this issue would be greatly appreciated. Thanks!!!Mi

[Bobmann]

Look at this: http://www.dairiki.org/hammond/wiring/

It is an interactive map of the keyboard. Click on the missing tones and it will tell you which tonewheels are the culprit.

When you determine what tone is missing, you can listen at the TG terminal strip.

Rule of thumb is that when all the tones for a particular TW are missing, the problem will lie between the TG terminal strip and somewhere in the TG.
Could be a bad solder joint at the terminal, bad cap on that tone, broken wire on the coil, or stuck tonewheel.
I just fixed an A100 with a missing tone last week. Turns out that this TG had the RC filters, and the little cap in the filter had opened up. I had a signal going into the filter, but none coming out. This was a first for me...never saw one of these go bad before.

If you only have a missing tone in one DB/Key combination, the problem is on the keyboard side of the terminal strip. Wires broken inside the insulation that are not visible, bad solder joints, or bad contacts or buss bar issues.

That should narrow it down.
Bob

[enor]

And, adding to what Bob said:

9 times out of ten, the problem is a broken connection at the tone generator terminal strip.

[David Anderson]

And, adding to what Bob said:

9 times out of ten, the problem is a broken connection at the tone generator terminal strip.

Especially on A-100s. Moving A-100s without locking the tone generator seems to produce more broken harness wires than on other models.

[kzinkmusic]

Agreed, was the tone generator tied down before moving? If not find the location on the generator for the missing tone,the coils are numbered. The last few hammonds I repaired with missing tones had broken wires on the backside of the T.G., going to the coils. The wires are shorter there and tend to break first. Another trick is to pull the 1 drawbar which has the missing tone in it. Then press the key with the missing tone down. Hold it down with a folded business card or matchbook. Now go into the T.G find the suspected area and check all wires, listen for the tone as the damaged wire reconnects the tone will sound. Good Luck