I dont know how or why, but now the problem is worse. I hooked up the amplifier back in the car and now I get a high pitched whine when the engine is running and a click or pop whenever any electrical device in the car turns on or off. The noise goes away when I unplug the RCAs from the amplifier. 
You need to check the RCA shield ground of the head unit.
http://bcae1.com/images/rca/temporaryrcashieldrepair.html
Also check for voltage on the RCAs of the amplifier. With the amp on, your multimeter set to DC volts and the black probe on the chassis ground terminal, touch the red probe to the RCA shields (no RCA cables plugged in). Do you read any voltage?
You stated earlier that the noise (crackling/popping) remained when you removed the RCAs. Has that changed?
Do you have a speaker that you can connect to the amp in the vehicle but is in no way connected to the vehicle? If so, disconnect all other speaker wires from the amplifier and connect the test speaker. Does the noise remain the same?
As a side note, it's not good to use your computer as a signal source when dealing with an amplifier that's not working properly. If the transformer is shorted, it can blow your sound card or damage the motherboard.
http://bcae1.com/images/rca/temporaryrcashieldrepair.html
Also check for voltage on the RCAs of the amplifier. With the amp on, your multimeter set to DC volts and the black probe on the chassis ground terminal, touch the red probe to the RCA shields (no RCA cables plugged in). Do you read any voltage?
You stated earlier that the noise (crackling/popping) remained when you removed the RCAs. Has that changed?
Do you have a speaker that you can connect to the amp in the vehicle but is in no way connected to the vehicle? If so, disconnect all other speaker wires from the amplifier and connect the test speaker. Does the noise remain the same?
As a side note, it's not good to use your computer as a signal source when dealing with an amplifier that's not working properly. If the transformer is shorted, it can blow your sound card or damage the motherboard.
You're a genious! 
All the RCA shield grounds are open on my head unit Another thing to fix now.
I checked the voltage of the RCAs on the amplifier and, at first, they were all around 40mV except for one of the front channels which was at over 300mV and then gradually went down. I rechecked a couple of minutes later and they were all around 40mV. When the engine was running, they were all a bit higher.
I am not able to hear the crackling/popping relating to the original problem now, but I'll find out if its gone for good once I fix the head unit.
I plugged in one of my computer speakers to the amp, and the whining/clicking sounds from the engine/electrical devices was still there. (which should stop once I fix the RCA shield ground problem on the head unit).
All the RCA shield grounds are open on my head unit Another thing to fix now.I checked the voltage of the RCAs on the amplifier and, at first, they were all around 40mV except for one of the front channels which was at over 300mV and then gradually went down. I rechecked a couple of minutes later and they were all around 40mV. When the engine was running, they were all a bit higher.
I am not able to hear the crackling/popping relating to the original problem now, but I'll find out if its gone for good once I fix the head unit.
I plugged in one of my computer speakers to the amp, and the whining/clicking sounds from the engine/electrical devices was still there. (which should stop once I fix the RCA shield ground problem on the head unit).
Perry Babin said:
Its a Pioneer DEH-P4800MP. I took off the top cover that just snaps off by prying with a small screwdriver. I took off all the screws on the sides of the head unit. The only screws that are left are the ones that hold the CD player cage to the circuit board and the outer head unit cage. My small screw driver keeps slipping. I need to get one that is slightly larger. The screws seem to be torqued on very well.
The ones that screw into brass standoffs can be difficult to break loose. Get a screwdriver that fits very well. If you let the screwdriver slip too many times, the head will become hopelessly stripped.
You may want to use the temporary repair shown on that page until you determine if there are any other problems. A faulty amp can cause the internal fuse for the shield ground to open.
You may want to use the temporary repair shown on that page until you determine if there are any other problems. A faulty amp can cause the internal fuse for the shield ground to open.
My head unit has 2 pairs of pre-amp outputs in the back (Front and Subwoofer) and another pair on a small cable sticking out the back for the Rear outputs. I checked the resistance of the RCA shield grounds on the head unit (Front and Subwoofer) and they are all connected. I then checked the resistance between the rear speaker outputs on the cable and the other two pairs of outputs and the RCA shield grounds are not connected. Is that the way its supposed to be? Should I put fuses to ground on each pair? Or just two fuses going to front+SW and the rear outputs?
Is it OK to use 2A fuses for the temporary solution? I also bought 1.5A fuses of the glass type with fuse holders, but I was planning on returning those since they cost more than the 2A fuses and holders.
Is it OK to use 2A fuses for the temporary solution? I also bought 1.5A fuses of the glass type with fuse holders, but I was planning on returning those since they cost more than the 2A fuses and holders.
I connected the fused grounded wires to one RCA of each pair (Front and Back) since the RCA shields are connected internally anyway. I was not able to connect a wire for the subwoofer output.
The engine and electrical noise went away for the most part (I think I still hear a faint pop when I press the brake pedal). I noticed that I can hear the head unit's CD motor humming through the speakers when I am playing a CD, but it goes away as soon as I switch to radio. I only noticed the CD motor hum when I turned the volume all the way to 0.
The engine and electrical noise went away for the most part (I think I still hear a faint pop when I press the brake pedal). I noticed that I can hear the head unit's CD motor humming through the speakers when I am playing a CD, but it goes away as soon as I switch to radio. I only noticed the CD motor hum when I turned the volume all the way to 0.
I now know (or think I know) what caused the ground fuse to blow. I had been plugging and unplugging the RCAs while the system was powered while troubleshooting the original problem. I think I'm just going to fix the fuse and turn off the amplifiers and head unit prior to changing the connections from now on. Do all Pioneer head units use a "P" fuse or are the all different. I havent been able to access the circuit board of my head unit and I want to order replacement fuses so I have them ready to install by the time I am able to remove the screws.
Connecting/disconnecting the RCAs while the amp and head unit are on will not damage the shield ground. It may damage the amp or speakers if there is a loud pop when you make the connection.
Generally, The shield ground is damaged when the RCAs contact a 12v power source or (on some amps) if a speaker wire shorts to ground.
Most use a 3 amp fuse (cek1286) in the shield ground.
Generally, The shield ground is damaged when the RCAs contact a 12v power source or (on some amps) if a speaker wire shorts to ground.
Most use a 3 amp fuse (cek1286) in the shield ground.
I just remembered that while I was using the screwdriver to connect the speakers back into the amplifier, the screwdriver touched the metal casing of the amplifier as I was turning it. I heard loud pops and my subwoofer also popped loudly (which is on the separate amplifier) so this must have been what caused the fuse to blow. The short went all the way to the head unit, and then back to the subwoofer amplifier which is what made it pop loudly.Perry Babin said:
I'm getting ready to order the fuses through Newark.com, I just want to verify that they are 1206 SMD size?
I ordered six 3A fuses. Three that are Littelfuse 0603 (434 series) and three that are 1206 (431 series). I'll let you know which one is the same once I get them. I think I'm going to have to file down the tip of my screwdriver since it doesn't fit well, so I havent been able to take the head unit apart completely.
When I searched for the part number (cek1286), I saw that they were being sold for more than $2 each.
The ones I got from Newark were about 50 to 80 cents each
When I searched for the part number (cek1286), I saw that they were being sold for more than $2 each.
The ones I got from Newark were about 50 to 80 cents each - Status
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