Pioneer RCA preout noise prevention

[cam2Xrunner]

For those who have ever had noise issues with their 880PRS or other deck, this post might help.

as far as the noise issue with the RCA's... i've seen it a million times. the very last thing you want to hook up with these units, is the RCA's at the head unit. too many times i have seen people hook up the RCA's at the head unit first, and then ground the center pin of the RCA's accidently. even with the unit unplugged, the capacitors hold a small charge, and that small charge can take out the final RCA output transistors, and also the caps themselfs.

the result is, noise. sometimes serious noise, that the unknowlegeable "fix" by grounding the RCA sheilds... but some noise still remains until the transistors and caps are replaced.

bottom line, to avoid this, make all connections of the system, and the very last thing to do, is plug the RCA cables into the head unit. since the 860/880 has a detachable RCA harness , best to leave the harness unplugged until last.

He's an EE and does repairs, and new product R&D for Pioneer, Alpine, JL, etc.

[chad]

Well, I was under the impression that it popped a Pico fuse. Regardless to touching the pin to ground it's still a shitty implementation. I've made MILLIONS of connections, even ones that naturally touch ground (shield on a 1/4") and have NEVER popped an output stage, or input stage for that matter on an ocsasional pahntom powered hot patch.

Poo Poo to pioneer for that output design, it's poor and that's undisputed.

Good call on the caps though I wrote this in a PM to a member which may give a bit of insight as to why this happens.

Generally the problems arise after reading this.... "All I did was hook it up and un-hook it" there is no concrete answer of any amplifier grounding scheme that causes the failure but more of an issue of connection/disconnection. I would suspect even sometimes hot-swapping...... Bla Bla Snip


A schematic would certainly give me a "yep this is how it wants to run" and I find it pretty awful that pioneer is keeping so hush about this and not telling us WHY this is happening. So for now I recommend complete power disconnection during patching and certainly no "hot swapping" with everything powered up.

The output is more than likely cap coupled, I was experiencing issues while trying to run balanced input with this because the caps would develop a charge then discharge during on/off or mutings. This discharge of the caps during connection is what could be causing the pico fuse to blow, a cap, no matter how big, will try to deliver an infinite amount of current during a shorted discharge and will draw an infinite amount of current while charging with no current limiting. I'm thinking this paired with an under sized protection scheme (most heads just use like a 0 or 1 ohm FP 1/4W resistor) is causing the issues, which, are blown pico fuses. A simple fix for a service center wanting to make a quick buck unfortunately.

So does anyone with a manual want to elaborate on a hook-up scheme from pioneer? Is it power last or RCA last?

[kyheng]

For safety, to prevent noise on Pioneer HUs, power is the last to connect, no hot swapping(change to get noise is very high)

[Lightninghoof]

This is somewhat unrelated, but I've had too many Pioneer/Premier HU's fail over the past 15 years to give them any more of my money. From faceplate backlights failing, to whine/ground issues that pop up out of nowhere, to CD read errors, etc. Just feels like disposable car audio to me.

It's funny, I have home audio equipment that has lasted 20+ years and still going strong, but car audio equipment won't last for more than 2 or 3 years without malfunctioning, and I baby this stuff. Your average teenager probably gets 6 months to a year of use out of it, if he is lucky.

[MidnightCE]

Originally Posted by Lightninghoof

This is somewhat unrelated, but I've had too many Pioneer/Premier HU's fail over the past 15 years to give them any more of my money. From faceplate backlights failing, to whine/ground issues that pop up out of nowhere, to CD read errors, etc. Just feels like disposable car audio to me.

It's funny, I have home audio equipment that has lasted 20+ years and still going strong, but car audio equipment won't last for more than 2 or 3 years without malfunctioning, and I baby this stuff. Your average teenager probably gets 6 months to a year of use out of it, if he is lucky.

your house doesn't constantly vibrate and jar, or subject the stuff inside to 130+ degree temperatures. Or require as much stuff to be packed into one little space.

[Boostedrex]

Originally Posted by MidnightCE

your house doesn't constantly vibrate and jar, or subject the stuff inside to 130+ degree temperatures. Or require as much stuff to be packed into one little space.

Not to mention that the power supply for your home gear is constant and doesn't fluctuate.

[chad]

Originally Posted by Boostedrex

Not to mention that the power supply for your home gear is constant and doesn't fluctuate.

I have my own 25KVA pole pig and it's still all over the place. I couldn't imagine sharing with others like I used to, it was REALLY all over the place then.. The only thing you can count on with home AC is that it will always be spot on 60 cycles.

[Lightninghoof]

It still blows balls to purchase a $600 HU, baby it, and only have it last for 16 months.

[cam2Xrunner]

Originally Posted by chad

Well, I was under the impression that it popped a Pico fuse. Regardless to touching the pin to ground it's still a shitty implementation. I've made MILLIONS of connections, even ones that naturally touch ground (shield on a 1/4") and have NEVER popped an output stage, or input stage for that matter on an ocsasional pahntom powered hot patch.

Poo Poo to pioneer for that output design, it's poor and that's undisputed.

Good call on the caps though I wrote this in a PM to a member which may give a bit of insight as to why this happens.



So does anyone with a manual want to elaborate on a hook-up scheme from pioneer? Is it power last or RCA last?

Here's another reply he typed afterwards.

completely forgot to address the ground problem issue... what people refer to the microfuse.

i've also seen this happen. a lot of times, when people dont have a good ground to their amps, or in some cases, forget to connect a ground altogether, the amp trys to get ground through the RCA cables. after all, with no main ground, the only path to ground is the RCA cable shields through the head unit.

this will take out the microfuse, which results in a lot of noise.

is it a bad design ? well... yes, and no. i've had Alpines, Eclipses, Clarions, Kenwoods, etc, etc, that have had this done to them, and the damage suffered is always worse than on the Pioneers.

on the other hand, they do seem a little overly sensitive. safe thing is to always make positive that your amps are properly grounded before turning the system on.

[solacedagony]

Originally Posted by chad

So does anyone with a manual want to elaborate on a hook-up scheme from pioneer? Is it power last or RCA last?

As per a yellow paper saying "Warning" on it:

"Always remove a connector from the (-) battery terminal before beginning any connection or installing work.
...
When installing this unit, always connect he ground wire first. Ensure that the ground wire is properly connected to metal parts of the car's body. (Fig.3)
...
When connecting the power amp (sold separately) to this unit ensure that the ground wire for the power amp is properly connected to metal parts of the car's body. Connect the ground wire of the power amp with a different screw from the one you used to connect the ground wire for this unit or any other device. Should the screw for the power amp's ground wire loosen or fall out, it may result in this unit emitting [magic] smoke or malfunctioning. (Fig.3)"


So they're saying to not use a common ground and to hook up the ground wire FIRST. What about if your ground wire is on a harness? Constant, memory and ground will all be connected simultaneously.

[Nathan P]

I'd say make sure the batt is disconnected and you'll be fine. I didn't do this, but I guess I got lucky. I always disconnect the batt when I do stuff, guess I forgot this time good thing it turned out okay, that'd be an $$ mistake.

[dalinkwent]

So is there any write-up or anything of that nature that shows how to fix this problem? I only ask because unfortunetly I am one of the many that has been effected by this problem and to top it all off I am just past warranty. I would much rather try and fix this problem then to try and fork over another 350 for a hu.

[chad]

Originally Posted by solacedagony

As per a yellow paper saying "Warning" on it:

"Always remove a connector from the (-) battery terminal before beginning any connection or installing work.
...
When installing this unit, always connect he ground wire first. Ensure that the ground wire is properly connected to metal parts of the car's body. (Fig.3)
...
When connecting the power amp (sold separately) to this unit ensure that the ground wire for the power amp is properly connected to metal parts of the car's body. Connect the ground wire of the power amp with a different screw from the one you used to connect the ground wire for this unit or any other device. Should the screw for the power amp's ground wire loosen or fall out, it may result in this unit emitting [magic] smoke or malfunctioning. (Fig.3)"


So they're saying to not use a common ground and to hook up the ground wire FIRST. What about if your ground wire is on a harness? Constant, memory and ground will all be connected simultaneously.

That, and if it's TRULY an issue of charged caps... and the caps are doing their job.... with no bleeder resistors.... we are still shot.

[60ndown]

Originally Posted by dalinkwent

So is there any write-up or anything of that nature that shows how to fix this problem? I only ask because unfortunetly I am one of the many that has been effected by this problem and to top it all off I am just past warranty. I would much rather try and fix this problem then to try and fork over another 350 for a hu.

i paid $145 locally to have my noise fixed

if your good with a soldering gun and electronics i guess you might be able to do it yourself for $4?

im not that good with it tho.

[solacedagony]

Originally Posted by chad

That, and if it's TRULY an issue of charged caps... and the caps are doing their job.... with no bleeder resistors.... we are still shot.

So you're pretty much trying your luck every time you hook this thing up?

[chad]

Originally Posted by solacedagony

So you're pretty much trying your luck every time you hook this thing up?

If I say yes would I be a hater?

Without seeing the guts or a schematic I can not give a definate answer so I will remain quiet

Chad

[solacedagony]

Originally Posted by chad

If I say yes would I be a hater?

Without seeing the guts or a schematic I can not give a definate answer so I will remain quiet

Chad

If it's easily tear-apart-able I'll get some gut pics for you. If not, we'll be in the dark forever

So the problem is with these capacitors in the pre-outs? Should you discharge them every time you unhook the unit or what?

[60ndown]

Originally Posted by solacedagony

If it's easily tear-apart-able I'll get some gut pics for you. If not, we'll be in the dark forever

So the problem is with these capacitors in the pre-outs? Should you discharge them every time you unhook the unit or what?

880,

http://i11.tinypic.com/2gwukom.jpg

[chad]

Originally Posted by solacedagony

If it's easily tear-apart-able I'll get some gut pics for you. If not, we'll be in the dark forever

So the problem is with these capacitors in the pre-outs? Should you discharge them every time you unhook the unit or what?

God only knows..... I believe the majority of the issues WE ae having are with blown pico fuses protecting the shield I imagine. I'm wondering if they are not coming up in charge with nothing attached then when attached or coming in contact with ground blowing the pico fuse.

Is the shield on a working 880 ground? or floating?

Chad

[60ndown]

http://www.elitecaraudio.com/forums/...hreadid=137088

[solacedagony]

Originally Posted by chad

Is the shield on a working 880 ground? or floating?

Chad

How can I tell? Is there a way I can measure continuity to find out?

[effenay]

Originally Posted by cam2Xrunner

For those who have ever had noise issues with their 880PRS or other deck, this post might help.

Great thread Cam! Thanks for the info.

Who is the source of the original quote in the first post?

Link available?

[Mat Dope]

if anyone has any DIY repair info for these HUs it would be nice. my 860 has bad noise now, and the wire around the rca ground doesnt help any more.

[chad]

Originally Posted by solacedagony

How can I tell? Is there a way I can measure continuity to find out?

If the shield of the RCA connector measures close to 0 ohms in respect to chassis ground/harness ground. If it measures low then starts climbing to infinity then it's cap coupled. If it measures say 200 ohm then it's isolated by a 200 ohm resistor.

These could be the Pico Fuses: (red circle near the top, tough to see around that cable)



Now... Does that big blue cap DC isolate the ground?

Chad

[solacedagony]

Will I have to have it plugged in to check that? Or can I do it without it being plugged in?

And none of that probing will result in a blown pico fuse, right?