would removing the pal007c amp ic damage a pioneer deh-p4900ib headunit?

[thebestofall007]

Hello diy'ers. I was wondering if it would harm a Pioneer DEH-P4900IB headunit if I removed the amp IC and used it like a preamp-only deck? I want to do this because I believe the amp IC is defective because the right front channel crackles (it outputs no sound at low volume, but when you turn it up, any sound from that channel crackles badly only when the music hits a hard beat). The preamp outputs don't do that, though.

However, I have also had the preamp outs output a pop pop pop pop pop (like a buzzing noise), and then all audio output shuts off (remote out too) every once in a while, but it has gotten more frequent (and more annoying!).

I originally thought the amps were drawing too much current from the remote output so I disconnected the remote from them, and hooked the remotes on the amps (I have two amps) to the car's accessory wire so they would turn on with the key like the radio, but that didn't solve the issue. I thought one of my amps were defective, so I disconnected the one for my front/rear speakers (to troubleshoot) and went to hook up the internal amp outputs to the front and rear speakers and that's when I found the defective channel. I have also double triple whatever checked the wiring (even soldered and heat shrinked all wiring)-no avail.

I have a few questions: would a defective power amp IC cause that problem? If yes, can I remove the amp IC and just use the preamp outputs (like a preamp-only deck) if that would solve the problem and not create other issues (except maybe lose remote out)? I have never used the speaker outputs on the deck since I have owned it. I come to a conclusion that it might be a bad amp IC because I Googled this issue and found this link from someone who had a similar issue with a DEH-P3900MP: http://www.fixya.com/support/t445461...intermediately

If there are any other issues that could be causing it, please let me know.

Mr. Perry Babin, if you are out there, please chime in. I have been on your site, http://bcae1.com and it has a lot of goodies I didn't know before on electronics, car audio, and amplifier repair. Thanks for having it!

thanks!

[thebestofall007]

another nugget of info: i also tested the voltage between the outputs and the chassis of the deck with a multimeter and i'm getting ~3.08-3.11 volts with all outputs and the two wires for the outputs of the defective channel barely even register. i heard they should register about 6-7 volts.

[Perry Babin]

You'll lose remote turn-on if you remove the IC.

[thebestofall007]

Originally Posted by Perry Babin

You'll lose remote turn-on if you remove the IC.

Thanks for chiming in. That's what I have been reading per Google searches. I'm not afraid of losing the remote out, as I can use the accessory wire to turn the amps on when I turn on the key.

Do you know what would cause that nasty pop pop pop pop and then shutdown of the audio outputs and remote output? The deck would still work, but no outputs. I can turn off the deck for a couple of minutes and turn it back on and the problem abates for awhile.

[Perry Babin]

From what you posted, it sounds like the IC has failed. When any part of it fails, it can cause all sorts of problems with the speaker level output.

[thebestofall007]

Originally Posted by Perry Babin

From what you posted, it sounds like the IC has failed. When any part of it fails, it can cause all sorts of problems with the speaker level output.

I just got through downloading a service manual for the DEH-P4900IB deck for free and it looks like the IC might be causing it as its input pins are connected to the RCA outs. I wonder if the shutoff is happening because of some protection circuit that is tripped as a response to the IC malfunction? The shutoff happens with ALL outputs (line level and speaker level). I want to learn more about how to repair these Pioneer decks because I love their supertuners, especially their supertuner IIID and IV (I'm an avid DX'er).

[Perry Babin]

If the chip shuts down, it's likely to turn your amps off also.

[thebestofall007]

Originally Posted by Perry Babin

If the chip shuts down, it's likely to turn your amps off also.

I just got through removing the IC and the problem seems to have went away (not to mention the deck running cooler ). I am bench testing the deck and an amplifier on a battery as I type to see how things go, and so far, so good. I'll chime in again if the popping issue rears its ugly head or anything else comes up. Again, thanks for chiming in. I remember your advice you had when you were helping me on my Punch 40 DSM amp.

[thebestofall007]

Originally Posted by Perry Babin

If the chip shuts down, it's likely to turn your amps off also.

I just got through removing the IC and the problem seems to have went away (not to mention the deck running cooler ). I am bench testing the deck and an amplifier on a battery as I type to see how things go, and so far, so good. I'll chime in again if the popping issue rears its ugly head. I also noticed THEY DIDN'T EVEN PUT HEAT SINK GREASE between the IC and heatsink! That's a no-brainer. No wonder it failed.

Again, thanks for chiming in. I remember your advice you had when you were helping me on my Punch 40 DSM amp.