How do I connect my GK3 equipped guitar to an Electric Piano or Synth ?

Turn off PROGRAM CHANGE on the module then it will remain on whatever you set it. If you want to selectively do this on certain patches, you'll have to sit down and offer up a plan for exactly how you want it to work before I could comment further.

Sounds like the power supply needs repair. Often the capacitors are leaking (electronically) and they cause the equipment to not work properly.

A Gk3 cannot be connected directly to an electric piano or synthesiser. The 23 pin DIN connector connects the GK3 / GUITAR to a Roland guitar synthesiser which produces the synth tones . This unit can be connected via midi cable to any external keyboard or synthesiser...to produce different or varied tones from the external synth ........provided the devices are able to communicate with each other...see the midi implementation charts for each device for information....

One fourth of 8 hrs = 2 hrs piano

On the rear of the piano there will be two 1/4" jacks labeled Output Left and Right. One will be labled Mono as well. If you are using a stereo amp, use both, and if a mono amp use just the mono output. If your amp is a guitar type, connect a shielded cable with 1/4" phone jacks such as you'd use with an electric guitar from these jacks to your amplifier. If you are useing a home stereo amp, you will need a cable with 1/4" phone jacks from the piano to RCA phono jacks on the amp end.

You must connect a short jack cable between the GK2 or GK3 and you normal guitar jack out. Secondly, the switch on the GK should be in the middle, that will give synth & dry guitar simultaneously.

My Casio PG380 Synth Guitar...It lights up but no sound on the Synth..Any ideas..

Okay, maybe this is rude, but TOTALLY ignore Musicaldude's solution, if you haven't already found out the ugly way. Boosting the signal that goes into the KP will just make the input LED light up red and you'll hear digital clipping [gross] and eventually hit a ceiling of all-crappy-staticy-noise and no real guitar left. Having it in the FX loop, and the Headphone-out workaround are smart moves already, except the Headphone out adds noticeable noise/hum vs the usual outs. But to help close the gap between your guitar's volume and the miniKP's internal synths (and program 63 and 65's feedback noizes, which build up even louder than the synths) unplug one of the RCA plugs from the KP's OUTput, pick one, left or right, whichever. You'll notice this gives you a guitar volume boost. BUT its still not enough...the synths and 63 and 65's feedback are still speaker-blowingly loud. Check the manual, it says you can adjust the wet/dry volume by holding down Tempo and Preset A together, then turning the knob and picking 1 thru 99. Make sure you're on the synth setting you want to use already. Do this thing. Play the synth with your finger, while you lower the number with that knob. Stay around 50 if you've got the one RCA plug dangling, around 20 if both are in. Whatever you think matches your usual playing volume. When its where you like it, hold the A or B button (wherever you want to save this) down and click Hold, this will save it onto that preset button. Now from now on, NEVER use 63, 65, or the synths if you're on whatever preset you DIDN'T just save. i.e. If you chose preset B, from now on you can just tap preset B and it remembers your volume adjustment from before, voila, normal-volume touchpad synth. But go back to preset A for every other effect, or you'll barely be able to hear the FX. KORG should've given us more preset buttons to save onto. Godspeed. I've never seen this site before, but I have this pedal, and experienced the same b.s. myself. Now I'm down to one preset button and quick knob-turning. Whee.