Turned volume up all three amps shout down at one time

Have you checked your speaker wiring as it could be you have some wires crossed ie: negative feeding the positive side causing the shut down & check the Ohms if at high volume you are trying to drag to many Ohms it will also cause the built in amp to shut down to protect the system dont keep incresing the volume as the strain will do damage

You may have to reset it. With the device turned off, press and hold the volume down button, and then briefly press the power button. - Wait for the screen with the three Android images to appear, and then release the volume down button. - Press volume down to select clear storage, and then press power. - Press volume up to start the factory reset.

Options: 1. Volume is turned down on player, 2. Volume is turned down on headphones, 3. CD jack is defective, 4. Headphone cord is defective, 5. Amp is defective, 6. Amp is disconnected, 7. Amp is turned off, 8. Speaker selector on amp is not selected properly to route audio to speakers. I hope one of these helps you find the issue. If using speakers, try headphones, or vice versa.

You are overloading your amp. IMO 640A cannot handle heavy loads.

Better change the speaker combo and connect something that puts right load on the 640A. Else, get a meaty amp from CA.

That a new one for me, it just goes full blast huh? I don't have an answer for that, but your amp can shut off because of a lot of reasons.
One you might not have enough power running to this amp. Check to make sure your amp gain is not turned all the way up, this is NOT the volume for the amp. It's to get your amp and the head unit on the same page (i.e. if the radios at 50% volume and so is the amp) if you turn it down too low that will make the amp very sensitive to volume adjustments, and your amp will be at 100% while the raidos at like 50 or 75%. And once you go past the 50 or 75 on the radio the amp, it's going to keep trying to play higher even though its already maxing out which is going to cause it to clip and cause distortion untill it goes into protect mode. Common mistake with a lot of people.

Two you might check all your wire connection to the amp. Three internal damage. The list can go on and on as you can see. RCAs might be damage or even your remote wire. Upgrading your alternater and battery can help.
Some people would even say to check your car factory amp (some times in the trunk or in between body panels) to see if it is bypassed. If it is not bypassed it could be a posability to shut down the other amp caused by to much power causing it to shut down. hope this was helpful

speaker voice coils could be overheating as amp is too powerful for them or it could be the same thing except the amp!

Hi there. you need to check that the signal going into you amplifier is not over driven. If it is, you will have the same effect of distorted bass. Turn volume on your radio down to see if that helps. If you have a Line driver and Crossover, then check them aswell. Remeber that your gains are not actually volume controls like people think, but rather level matching adjustments. Shout if you need more info.

I'm not a complete audio expert but it sounds like somethings over heating or you have a blown out put bridge.

not enough power to amp and or amps location is too hot might want to invest in a couple cooling fans from computer store and attach where needed

an amp should take up to 3/4 load but when not enough air to it to cool it off it will shut down

try this turn gain all the way down and slowly work up too desired amp volume setting

Every time when i turn on my bose system the volume is all the way high in all the modes eg - aux,vedeo.... ,then i can make it less manually on remote/front keys on music senter.