Allen 301-B Organ Problems-- Flute Division Volume Control & Percussion Tab

[James P]

After posting this new problem with my "2nd" Allen 301-B organ this morning on my initial/old post, thought perhaps it best to start new thread-- since it's a different organ/but same model as before.
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John, Michael, Larry, & all,

Received my 2nd Allen 301-B organ past weekend. Was advertised as in “mint condition” —not so!! ( But fits in my home/space—unlike my ADC-7000! LOL)
After a lot of cleaning, Mntnc, etc, all playing now except for:

1) flute amp channel/speakers volume initially did—& does each time I unplug/plug input line, but doesn’t retain volume control by Swell/left Pedal—just for awhile, and then reverts to its full preset volume as adjusted on amp gain. I can turn amp gain up/down & effects volume, but not by Swell pedal -- after a few minutes. Is my problem w/defective Flute amp—or otherwise? Swell pedal does control Great/Pedal volumes just fine from the other Main amp, and there is a 3rd amp/channel mounted on top right of console --for Pedal stops, I assume. (My previous 301-B had only the 2 amps mounted on floor of console.)

2) when I use Percussion tab on Great manual w/Alt 3 or 4 tab, any 1st note played will keep playing, as if stuck/still depressed. If I don't use the Percussion tab w/programmed voice card, it plays as it should.

Any thoughts/suggestions on what the solution is for these problems?
Thanks!

James

[jbird604]

James,

I have a few thoughts on this...

(1) The lack of expression on the flute/pedal channel could be traced to a number of problems, all of them fairly minor. You don't have a bad amp. The first thing that comes to mind is that the RCA plug on the amp in the "Exp" jack is not firmly seated or is losing contact after warmup. Clean, apply Vaseline, re-install firmly. Then check to be sure the shielded line that runs from the expression shoe's LDR cell has a reliable path all the way to the RCA plug on the amp marked "X" or "Exp". The cable could be interrupted somewhere, so trace it carefully all the way. If it's not the plug or the cable, it could be the expression capacitor on top of the amp, or a solder joint on the inside of the amp in the area of the expression or signal input jack. Last possibility is that the LDR in the expression shoe is failing, or that the lamp in the shoe is about to go out. Check the lamp, and you may have to open up the shoe and clean or even replace the LDR, but that is not likely.

(And yes, the 3rd amp is the optional bass boost amp, which can be connected to a subwoofer cabinet if you want more pedal volume.)

(2) The percussion issue is peculiar. Could be a problem with the KBA board or the MOS board itself, but more likely to be a simple maintenance issue. Have you cleaned up all the connectors and plugs going to all the boards? That is the first step, which often solves a bunch of problems. Everything must be firmly and cleanly connected for the system to work properly.

Does your organ have an external sustain length knob on the front of the console (small round black knob)? If so, sweep it through its range a few times. If it isn't there, there should be a sustain length thumbwheel pot on the KBA, which might also need to be cleaned or adjusted.

[James P]

John,
Thanks for your suggestions on all. I’ll do all—starting w/cleaning all connections & applying Vaseline to plug. Never thought of doing such or that it could help make a good connection.
Also the MOS Board is the power Board in middle of console backside, but what is the KBA Board—& where is it located?
Thanks again!!

James

[jbird604]

KBA board is a rectangular board, quite a bit smaller than the MOS. It is mounted down low on the same panel as the MOS board in most arrangements. It will have KBA on the white paper label. You should see some thumbwheel pots, and one of them might be sustain length. I think that is also where you'll find the tremulant speed adjustment, and a few other odd adjustments that don't do much.