Conn 717 pedal issue

[djseverus1]

I finally decided to open up my Conn 717 to try and figure out why my pedals are malfunctioning. The stops 32,16 flutes, 16,8,4 principals, and 16 reed are all intermittent. 8,2 flutes and couplers work fine, every note. Which notes work and which don't changes every time I turn the organ on, there are no notes/stops that are consistently bad.
I have the service manual and can follow the schematic, but I'm confused by the terminology and what these parts actually do. For example, why are there two identical circuit boards (part 72424-017) with identical connections, one labeled "Biphonic pedal synth keyer" and the other "LSI pedal synth keyer? What's the difference? Here's a picture:



A simple explanation of how the system is supposed to work from someone who understands these things would help me a lot in trying to troubleshoot.

Random funny thing, when I raised the Great manual on its hinge, there was the name "Terry Dickerson" scratched on the wood beneath it. Probably an old Conn factory employee?

[Hamman]

Sorry I won't be able to help....but I use to have a 717...and I still have a 716. My 717 did the exact same thing...I ended up trading the whole organ for some Leslie speaker parts, etc. from a tech guy I know. He said it took him numerous hours to get that organ up to snuff and claimed it was built in the Kimball era of time that they owned Conn. I had my 716 hooked up through 2 720 Leslies and I was quite impressed with its sound. Hope you get it figured out!

[tucsondave]

The boards in your photo are basically voicing filters. The square wave from the pedal generators are divided and filtered. One pedal note per board. Two identical boards, one for each of the two "biphonic" pedals being played.

The first thing to do is confirm the proper power supply voltages at the various pedal boards. Make sure there is no AC component, just DC.

Next is to reflow the solder on all the circuit board connectors. In this case the pedal generator board (71824-023) and the Biphonic generator board (71824-025) would be where I would start. They both have an LSI chip on them. Do one board at a time then check the pedals.

Could you clarify what is wrong? Is it some pedals that are intermittent or the stops?

td

[djseverus1]

Awesome, thanks Dave. FIXED!

When I was checking the connectors on the generator boards at the bottom of the console, I noticed the single orange wire (LSI master freq. on the schematics) on the biphonic generator board was plugged into one of two possible 2-prong male connections on the same board. I plugged it into the other one on a hunch, and presto! all the pedals worked, with multiple-voice polyphony, on every stop. I can't believe it was that easy. I had never touched that board or opened up the console since I got the organ 2 years ago, so whoever had it before me must have plugged it in wrong. But why are there 2 such connections on the board if only one is used?

What had happened was some pedal notes would play, and others wouldn't. Oddly, holding down a "dead" pedal caused every other one to work, and holding down a live one caused every other one to be dead. No two notes could sound at once. It was like that since I got the organ, but I could stand playing with couplers always on until now when I became frustrated enough to try doing something about it...

Thanks again!

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By the way, does anyone have Conn pipes for sale? Now that my organ works better, I'd like to enhance the audio if I can.

[Hamman]

Where are you located? I have some 146 (tall) pipes I'd like to sell....2 sets of left/right (4 total units) and 1 set left/right of 145's (medium height)
PM me if interested