Tip negative for old Ibanez RC99 Chorus pedal?

[sleepingtiger]

I picked up an RC99 chorus pedal & want to try it, but being that it IS old, I wonder if it is a tip negative or positive? It doesn't take batteries, so I can't go that route. I'm using a Power=all, so I can set it up either way, but don't want to risk damaging it by using the wrong polarity.
Any help is appreciated!
Thanks!
Tony

[Mark Hammer]

When the pedal can use EITHER batteries or wall-wart, negative-ground pedals MUST use the outside shaft of the adaptor's barrel plug to bump the connection from battery to circuit board out of the way in order to replace the battery power with external power.

Unfortunately, when the pedal uses ONLY external power (no battery capability), there is no requirement for physically displacing a contact, and it becomes the manfucaturer's perogative to use tip-pos OR tip-neg. As you are no doubt aware, both types of plug wiring schemes exist. I'd say the odds are at least 60-70% likely that it uses tip-neg (outside-pos), but since you don't want to risk a beloved pedal to the other 30% probability, let's test first.

The simplest test is to pop the back off the pedal, and identify a ground contact. If there are op-amps in there, then pin 4 on any of them will be a ground point and you can probably use them to trace things back on the copper side of the board to identify a large surface area that you know is ground. Once you have ground identified, use your meter, set to continuity test (usually a beeper is built in), and touch one probe to that ground point and the other to the pin in the middle of the power jack on the pedal. If it beeps, then you know that its tip-neg. If it doesn't beep, then try and identify the solder of the jack connected to the outside contact and see if that goes to ground.

make sense?

[sleepingtiger]

Thanks for the help!

[Sweetfinger]

Its not THAT old!

I wouldn't characterize an 8 year old device as 'old'. IIRC that whole 99 series just used regular Ibanez AC 109 adaptors which were tip neg.

[sleepingtiger]

See? It shows what I know, hehe! I was undr the impression that it was late 80's/early 90's, but that was an assumption on my part. now to find the time to plug 'er in!
Thanks for all the help!
Tony

[tubetonez]

Yes, it is tip negative, I'm powering mine from a Godlyke. I love this pedal, very lush and warm stereo sound and it is more tweakable than most chorus pedals, with a mix knob that let's you go from subtle to extreme.