Behringer CT100...X Pattern on LED grid when testing a mono instrument cable

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.

Check instrument cable, cable jack on guitar, cable jack on pedal. If pedal has gigged much, the last is most probable

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.

I would check it with a different instrument cable AND bass guitar. If you end up with the same results, it's a thermal issue with the amp and will require factory authorized repair. The amp heats up and the intermittent component starts failing....more heat, more failure. It's not an easy fix and your Behringer repair shop will have their work cut out for them with this repair.

The connector should be a 6.3mm (quarter inch) mono jack plug. And don't buy the curly cable.

MAKE SURE the cables you plug into 1/4 inch mains are TRS plugs, and not mono cables (TS). The main output 1/4 inch jacks are TRS balanced outputs and if you plug mono (TS) cables that shorts out the ring connector reducing the power by 6 Db. USE ONLY TRS balanced cables for interconnects !!!! Also read my tip on Fixya regarding PMP mixers. If you use 1/4 inch SPEAKER cables or adapters, if you short the SLEEVE of channel A output to ground you can pop the channel A amp. The TIP of channel B is the hot BUT the SLEEVE of channel A is the HOT. The ttip I posted explains why this is and it isn't mention in the Behringer documentation.

Check battery and or power adapter and that the input and output cables are not backwards.

Please note that the outputs of the MAIN L/R line outs are TRS balanced. If you plug mono plugs into these or connect to mono device you MAY have a problem of grounding out half of the drive internally. ALSO please read my tip on here regarding a polarity hazard of speaker cables of PMP amps if you do NOT have Speakon to Speakon cables, but have Speakon to 1/4 inch cables.

Likely one of the power amps in this has failed If no lights come on the unit now, then the power supply is wiped out as well. It takes about $50 worth of parts and quite a bit of skill and work to restore the unit, including carving out burned board and re-insulating. Likely a feedback occured on that mic and started the whole thing. Supersonic feedback is something most musicians are NOT aware of, but if the feedback is above the range of hearing, the amps can be strained as they may go to maximum power trying to amplify the sound you can;;t even hear. Piezo tweeters are capable of frequencies up to 30KHz.

If this is under warranty exercise it immediately.

You would NOT use a stereo cable to plug in your guitar.

The stereo cable would carry the battery voltage back to the amp and MAYBE cause the fuse to blow.

You use a MONO instrument cable for your guitar.

The ring connection is use to complete the circuit to turn on the battery in most guitars.

Replace the fuse ONCE and get the proper instrument cable (NOT consumer audio cable) for your guitar.

If fuse blows again, take amp to shop for service.

This site has diagrams... not the best but clear enough.

PLEASE note that the pin numbering is kind of goofy... The pins of both the male and female tie to identical pin numbers.

You PROBABLY have misread the numbering at one end.

A KEY thing is to get the shield on pin 1 at both ends.

I recommend that you uncap BOTH connectors, mate them, and verify the same color goes straight across as you solder the wires..

Note: I had some brand new cables delivered that the shield had been connected to pin 3 (middle one) and I had hum ! Note that this defect would NOT be caught by your cable tester as there was conituity between corresponding pin numbers.