I have a 96 Impala SS with a Pioneer Premier head unit. I forget the model, but its from about 1999 or 2000 and its the pre-amp only with flip down face and single CD. If I recall correctly it might be a PH-78 or something. I'm running 4 gauge wire to the back where there are two amps. The amp running the fronts is a Kenwood 2 x 80w from about 1995 or 1996. The amp for the rears is a 2 x 75w Coustic from about 1999. Recently, all of a sudden, the audio started having problems. It became very "hissy," and anytime you changed radio stations or went from zero volume up, a very loud crack would come through all four channels. I double checked all of the grounds and power lines, as well as fuses and signal voltage to the amps. It all checks out. I adjusted gains on both amps to see if I could identify a problem, and I tried pulling the RCAs to one amp and then the other. The hissing stayed.
The fact that the hissing stayed and their age makes me think its an amplifier problem, but the fact that its coming equally from both amps, it happened all at once, and the cracking corresponds to changes in the pre-amp signal makes me think its a bad signal from the head unit. Any thoughts?
The fact that the hissing stayed and their age makes me think its an amplifier problem, but the fact that its coming equally from both amps, it happened all at once, and the cracking corresponds to changes in the pre-amp signal makes me think its a bad signal from the head unit. Any thoughts?
HU Repair
Hi curtis73. I repair these Pioneer units - used to work for a Pioneer warranty station. Commonly, there are circuit traces in the unit itself that either crack or burn up which is caused by either mechanical vibration or a poor ground connection to the chassis at the amplifiers. This especially happens in "cheapie" amplifiers since they reference the signal input shield to chassis ground. When the amplifier needs more ground....er...power, it tries to get it though the signal cable's sheild, thus burning out the head's signal ground circuit traces.
Anywho, symptoms match exactly to your experiences. Shoot me an email if you're interested. I'm pretty cheap.
See "Contact" on www.envisionelectronics.com for my email address.
Hi curtis73. I repair these Pioneer units - used to work for a Pioneer warranty station. Commonly, there are circuit traces in the unit itself that either crack or burn up which is caused by either mechanical vibration or a poor ground connection to the chassis at the amplifiers. This especially happens in "cheapie" amplifiers since they reference the signal input shield to chassis ground. When the amplifier needs more ground....er...power, it tries to get it though the signal cable's sheild, thus burning out the head's signal ground circuit traces.
Anywho, symptoms match exactly to your experiences. Shoot me an email if you're interested. I'm pretty cheap.
See "Contact" on www.envisionelectronics.com for my email address.
Hi,
I would start by isolating the low level outputs on your deck. If the problem is on all channels, you might have killed the muting transistors in the deck.
Very easy to do, just send 12v into your deck via the RCA cable & the first thing to pop is the muting transistors.
Good luck,
KevinLee
I would start by isolating the low level outputs on your deck. If the problem is on all channels, you might have killed the muting transistors in the deck.
Very easy to do, just send 12v into your deck via the RCA cable & the first thing to pop is the muting transistors.
Good luck,
KevinLee
Maybe, but that wouldn't cause the "hissing" sound he's getting. The mute transistors rely on the ground reference at the signal output. If that's fried, the transistors turn full "off" (unmuted) all the time and never mute anything, which coincides with your conclusion. The hissing is caused by the CD servo noise leaking into the output circuitry, because, once again - there is no reference ground.
Envision Audio
Envision,
Mine was hissing like you had turned up the gain on the amps 10 times what you could do with the dial. It hissed and you could hear tiny voices in the back, but changing stations or sources was a deafening crack. Sound like the solder/trace issues?
I'm very interested in your repairs, so I'll shoot you a PM or email.
Curtis
Envision,
Mine was hissing like you had turned up the gain on the amps 10 times what you could do with the dial. It hissed and you could hear tiny voices in the back, but changing stations or sources was a deafening crack. Sound like the solder/trace issues?
I'm very interested in your repairs, so I'll shoot you a PM or email.
Curtis
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