L100 Percussion circuit trouble

[enor@hem.passagen.se (Magnus Enorson)]

        Greetings fellow Hammondites

Yesterday I went to take a look at a friend's L100 which was having some
trouble with the percussion circuit.

When I got there, the top manual was making thunder noises only (no sound),
unless percussion was switched on, which caused a VERY loud perc tone, with
a great deal of thunder to accompany it.

I followed the signal chain to make sure the problem was really located in
the perc unit, and then took out and cleaned the connectors of the 12AX7
tube in the circuit. This restored the signal to normal when percussion is
switched OFF, but I still get loud thumps when operating any of the
percussion switches, as well as the vibrato/chorus switch which is also
connected to the perc circuit. Also the percussion only works with slow
decay and normal volume, if I switch to fast decay and/or volume soft, the
top manual goes dead again.

all connectors and all the switches are OK (I checked.)

Question: what do I do next? All suggestions greatly appreciated.


        Thanks in advance, Magnus

        Samuel (the owner) says thanks too


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* Magnus Enorson      *   Fender Precision bass                      *
* School of Music     *           GK amp, EBS speaker                *
* and Musicology,     *                     Hammond L100             *
* Gothenburg, Sweden  *                                Leslie 760    *
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*  GOD LOVES YOU !!!  HE ALWAYS HAS LOVED YOU AND HE ALWAYS WILL !!! *
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