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Joined:
October 2005
Posts: 4025
Location: Utah | Finally solved the preamp problem in the '97.
I tracked down the service manual and the patent with the schematic on Jerome's site. Tracing the connections showed a power polarity problem.The battery cable is non-standard colors! When I bought the guitar the battery was dead, so I put in a new battery, using the red wire as indicating + and the black wire as indicating -. This is one of those blind boxes inside the body of the guitar with a cable running to the circuit board attached to the endpin jack (where a shoulder strap attaches). No joy with the new battery either.
Anyhow, it turns out the cable/plug assembly Ovation used was intended for the opposite polarity than Ovation's application. Probably a pedal power cable.
The battery needs to be installed with the + terminal to the black wire, and the - terminal to the red wire. The schematic shows a protective diode to prevent damage to the circuit board if the battery is put in the wrong way. The plastic box has a slightly smaller slot for the smaller battery terminal to fit into which is the correct polarity (on mine at least) when putting the battery into the box, but it is only visible with the box removed and using good lighting. The battery will go in the wrong way despite the different sized slots, which is what I did.
So for anyone with a mysteriously dead touch-sensitive preamp in their parlor, try reversing the battery.
Edited by FlySig 2019-01-01 6:55 PM
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Joined:
September 2006
Posts: 10777
Location: Keepin' It Weird in Portland, OR | 
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Joined:
October 2012
Posts: 1018
Location: Yokohama, Japan | Hey FlySig. Thanks for posting this. I never even bothered to look until now, but my 97C (Vincent) has the same issue. I just always looked for the "+" marking on the battery case instead of the wire color proving once again that 'ignorance is bliss'! |
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Joined:
April 2013
Posts: 101
Location: NW Indiana | Hi FlySig, I read your post with great interest and GREAT hopes. I bought my '97 parlor (serial #0279) about 2 years ago, changed the battery and the strings and it sounded great plugged in, but the touch-sensitive strip on the side of the guitar did not work, had to adjust the volume & tone through the amp. So I couldn't wait to check out this battery reversal you talked about. Getting the battery box out of the guitar is a PIA, but once out I put in a new battery Positive to Black, restrung it...and not only was the touch sensitive strip still dead, nothing came out once plugged into an amp. So I got my big fat hand back in the soundhole, put the battery in with the positive connected to the Red wire....now it sounds great through the amp, but the touch-sensitive panel is still dead. So maybe some of the '97 Collectors are Red Positive, some Black Positive, but it sounds like they all have defective Touch panels? |
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Joined:
October 2005
Posts: 4025
Location: Utah | It is possible your touch panels are gunked up. Someone posted a cleaning method that worked for them a while back, probably somewhere on this forum. I'd try vacuuming them out and maybe wiping with some isopropyl alcohol on a soft lint-free cloth. |
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Joined:
April 2013
Posts: 101
Location: NW Indiana | Thanks, FlySig. I'll give that a try! |
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1997 Parlor Preamp
