Conn 651 piston repair tips sought

[EricS]

Folks:

I recently became the owner of a Conn 651.

Two of the blind pistons on the accompanymentmanual do not work. Meaning they physically can be pushed in and they return to the original position just like all the others that work. But they cause no action. The pistons are # 2 and 3. If I have already activated piston 1 and the corresponding light is illuminated on the indicator panel, when I depress piston #2, the light for piston #1 remains illuminated and the registration for piston #1 remains active. Ditto for piston #3. Pistons 0,1,4, and 5 work correctly.

The 651 service manual is silent on piston repair. The "little black box" that houses the buttons is attached pretty firmly to the keyboard tray.

Has anyone ever dealt with servicing the pistons on a Conn organ? If so, any tips will be much appreciated.

Thanks...Eric

[OrgansR4Me]

Re: Conn 651 piston repair tips sought

I'm guessing here since I have my Conn repair books packed away just now, but from your description of the "black box" I think you are referring to the tone modifier top center of the fallboard? You may need to disconnect, clean and check wiring inside the box itself. Second alternative would be to find someone parting a similar Conn. I've had a few with serious wear that weren't very reliable. Sometimes I've just gone ahead and used the modifiers that were working.

[Hemingray]

Re: Conn 651 piston repair tips sought



I would also be interesting in hearing how to get into the "little black boxes" that the pistons are housed in. I couldn't find anything in my Conn 651 service manual either.

A couple of my pistons (Chorus/Reverb/Tremolo) are also sketchy at best (you have to "wiggle" them to get them to turn on/off. My guess is just dirty contacts?

[Hemingray]

Re: Conn 651 piston repair tips sought



Hi Eric,

Okay, so I picked the brains over at the Conn Artistes Yahoo group and also took my own 651 apart to see how to get into these darn piston boxes. According to the group, these were never meant to be serviceable.

Well, I decided to see for myself. I removed the black metal facade that the piston boxes are attached to, and found that they are attached to it by flat-head screws in the back. They're on the key side, so it's impossible to see or get to unless you remove that facade. Once I removed the boxes, I had enough room to see how the switches are connected. They appear to be sealed plastic of some kind, and are indeed impossible to get inside the guts of the switch itself.

To be honest, I'm not even sure how the switch works, because the entire back of the piston appears to be plastic, even the loops where the wires are attached. I've never seen anything like it.

Getting that metal facade back on was a PAIN. All of the keys for the manual above use that metal strip as the felt stop, so in order to get it back on, all 61 keys must be pressed completely down at the same time. This is best done with at least 2 people and a long metal ruler. I managed to do it by myself, but it took about 15 minutes and a fair amount of cursing. :)

Long story short, I was able to get one troublesome piston to work again by spraying DeoxIT into the crack around the piston, and then pressing and wiggling it a lot. I would recommend lifting up the manual that the pistons are on so it's vertical. Gravity will do the rest. Good luck!