Mpg yellow oval

Question edited for clarity (with a guess at model).
Question moved from Television and Video.

If you want to check inside it, look for damaged components or blown or bulging capacitors. The best solution is to take it to a local electronics or audio store for repair.

https://www.google.com/search?q=crate+yellow+amplifier+no+sound

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WHEN THE YELLOW LED IS ON ALL THE TIME, IT MEANS ITS ON PROTECTION MODE MEANSNG IT HAS A FAULT. U NEED A TECHNICIAN TO CHECK AND CONFIRM THE FAULTY COMPONENTS.

You didn't say what instrument you're asking about, and various manufacturers use similar systems. You need to tell us the make and model. In addition, you haven't asked a question.. What can we help you with?

Yellow is positive, yellow/black is negative.

Peavey color indicates that Blue is Negative And Yellow Is Positive, so Yellow goes to + Speaker Terminal.

The effects or FX section is on the top right of the mixer. On your vocal channels find the yellow knob marked FX and turn it to 0. Choose the effect you need using the Program knob (top right) for karaoke this will probably be 03 or 06. Start singing and turn up the yellow knob marked 3 - FX under AUX Sends until the LEDs above them hit -0db, no higher.
Now find the button marked FX - Main Mix and make sure it is UP.
Turn up the yellow knob (3 - FX) next to it until you can hear enough echo on your mic.

Just giving the dimensions isn't going to get you the rright speakers. Many of these have different impedance speakers than common ones. You best go to Casio to find the specs or the replacements. You did NOT even give us the model number of your unit. Contact Casio support and parts to get correct units.

That is a very wide range cone type (oval) type tweeter that probably covers from around 2500 Hz up to 20KHz. You will probably NOT be satisfied with generic speaker... this one is special for sure. Try calling http://www.speakerrepair.com/ocsdiaphragms.html and see if you can get it reconed. Most speakers that are cheap will NOT take the power that the amp will deliver.

The consense is that the yellow is positive... However, if these come from a 1/4 inch jack, the color that connects to the TIP of the jack is the positive one..

Usually the yellow will be positive... Hint, it won't make a difference UNLESS you drive two of these in parallel as it only affects the phase of the cone movement relative to the input.

Connect the yellow to positive and don't worry about it further.