AM reception is much less sensitive to the connections of the antenna than FM stations are. For example, you might be able to receive AM stations with just the ground wire of the antenna connected to the radio and not the center wire (which connects to the antenna’s main mast). And some radios also use the main chassis ground as an additional reception point for AM so you might be able to get AM stations with no external antenna connected at all. First step is to check the integrity of the center antenna wire that connects to the antenna’s mast. There should be clean, low resistance connection between the antenna wire’s center connector at the radio and the main mast of the antenna. If you can, try connecting a different antenna to the radio and see if FM reception improves. That will tell you if there a break in the wires or some other fault with the original antenna.

The old-school rule of thumb for stiffening capacitors was 1 farad up to 1000 watts. So 3 farads should be good for about 3000 watts. But there are lots of other factors, such as the impedance that the amplifiers are driving and the type of capacitor (normal, hybrid, carbon, etc.). Low impedance loads, such as 1-ohm subs, will draw a lot more current from the amplifiers than a higher impedance load. If you’re really running 8000 watts, then you’ll likely need a second battery and an isolator in addition to stiffening capacitors. And 3 farad might not be enough, especially if your subs are wired to a low-impedance load. 8000 watts is an awful lot of power to be running through a car’s electrical system, so plenty of power supply upgrades are going to be needed to avoid straining the rest of the car’s electronics (and the lights).

That looks like a ceramic capacitor. The 10.0 refers to 10 micro farads and the 100V refers to 100 volt breakdown voltage. The J is the tolerance, which is +/-5%. The FMK markings are probably manufacturer codes.

Most car CD players will eject the CD with only the constant (memory) lead getting power. So if the switched power lead (usually red color) is not getting power but the constant lead (usually yellow color) is getting power, then the head unit won’t turn on but it will eject the CD. So check the switched power lead and make sure it’s getting 12V when the car is turned on or the key is switched to ACC.

Check the sub’s amplifier to see if it is still powering on. If the sub’s amplifier isn’t working, then you might be getting just highs and no lows because of the crossover settings in the UV10 or other amplifiers you have in the system. If your main speakers are running off an amplifier, then that amplifier might have a crossover setting that just sends highs to your main speakers. If your main speakers are running directly off the UV10 head unit, then go into the settings menu for the UV10 and disable any crossovers. That should send full-range signal to all the speakers that are working.

The CD mechanism is probably dirty or misaligned. If the tracks that the lens assembly rides on wear out or lose their lubrication, then the lens can’t travel all along the CD path like it needs to. So then it can only play a certain section of the CD before it gets stuck. You can try a bit of compressed air through the CD loading slot, but most likely the CD player will need to be disassembled in order to do a thorough cleaning and relubrication of the CD mechanism.

I’d check all your grounds first. The protection mode and the heartbeat sound can be caused by a poor ground connection or a bad ground-loop problem. Even if the amp’s ground connection looks okay, try a different grounding point for the amp and see if that helps. Once the amp’s ground and power connections all check out, then double-check the grounding for all the other car audio electronics in the car including the head unit. You can also try a ground-loop isolator inline with the signal cables, but that will only help if the amp is working and you still get noise (along with regular audio) through the speakers.

Next step in troubleshooting would be to provide a known good audio signal to the sub when the car is on (and the sub’s power light is lit). You can use an audio output cable connected to an iPod or your phone, for example. If the sub works with an alternate audio source, then you know the issue is either the connections between the sub and the head unit or an issue with the head unit itself. If the sub still doesn’t work with an alternate audio source, then the issue is probably with the sub’s internal amp which wouldn’t be an easy fix. The internal amp can be defective even without the protection light going on.

There might be an issue with the remote turn-on lead. Some radios don’t provide enough current out of the remote lead to turn on multiple amps. Try running 12V from the battery to both of the amps remote turn-on leads and see if they both turn on. If that works, then you can use a relay connected to the radio’s remote turn-on lead and switched 12V power to switch your amps on. Also check to see if you get a voltage drop when both amps turn on at once. It’s possible that one of the amps is going into protection mode due to under-voltage. There could be a wiring, car battery, or alternator problem that isn’t supplying enough current for all your car’s electronics.