Bad/Open RCA Shield on Pioneer DEH-P7100BT Head Unit

[paulieb81]

I have been chasing a nasty engine whine in my system all day, checking every wire and ground there is. Finally after an entire day from noon to almost midnight, I have found my answer through searching on here and testing.

It is an open RCA Shield on my head unit as directed here:
RCA Shield Repair

I did this simple test, and all noise went away.

Now previously two weeks ago, I blew an Alpine MRD-M605 amp here:
blown alpine mrd m605 amp

I am not sure if these two are related, or if the blown amp caused the ground in my new head unit to blow. If anyone could shed any light on this please let me know.

My Pioneer DEH-P7100BT head unit is brand new, only two weeks old, I could exchange it or repair it, please advise what would be the best course of action.

[Perry Babin]

If it's under warranty, don't try to repair it.

It's possible for some amplifier faults to cause the shield to open but it's relatively rare. In most all cases, carelessness during the installation of the system results in the blown shield fuse.

[paulieb81]

hmmmmmm.... whoops I guess. An exchange is in order. Thank you for the fast reply.

Could this explain what may have happened to my amp at all?

[Perry Babin]

It's unlikely that an open shield would cause a class D amp to fail.

[paulieb81]

I understand that, but whatever installation mishap I may have done that caused the open shield, could that have also blown the amp?

The weird thing about the amp being blown, is that it worked just fine for two days, then the 3rd day, I turned my truck off to go eat lunch, when I came back out, it was not working.

[Perry Babin]

The damage to the head unit likely came after you removed the amplifier for troubleshooting.

[paulieb81]

Now if I can only find my receipt. If not, where is the likely place to investigate the open ground on the inside?

[Perry Babin]

Pioneer uses an SMD fuse on most (all?) of their newer head units. Some are almost microscopic (0.060"x0.030") and can be difficult to replace.

[paulieb81]

not sure if this also goes along with this problem, but I noticed that when I had it hooked up the other day, my gain on my amp was all the way down to the minimum. The head unit is supposed to put out a 4v signal therefor should the amp not also be set for 4v, rather than 100mv? As I turned the gain up, the sound went down, therefore lowering the amp output.

[ZippyTs]

The reason the fuse blew most likely is you disconnected the amp ground before you pulled the rca's causing the radio to act as a ground for the amp and popping the fuse. With a pioneer deck all equipment including the deck should be properly grounded before connecting the rca's or you blow the picofuse. I also found out the hard way, and used a single strand of 32+ awg wire to bridge the fuse. Perry is right that sucker is tiny. I have a mainboard for a deh-p780mp here I will try to take a pic of it later tonight to show you.

Zippy

Also it had nothing to do with the gain