Modifing stock head unit

johnm_10 · 6th April 2006, 10:59 PM

Just wondering if anyone knows of a guide somewhere that would help me modify my stock head unit. I want to add line out jacks. I think it would just be a matter of finding the correct solder positions on the board before the signal is amplified.

Any ideas?

Thanks

Perry Babin · 7th April 2006, 12:42 AM

If the head unit doesn't have preamp level outputs, there may be no suitable signal in the head unit. The output ICs typically have high gain and therefore the signal they receive is typically very low. To drive a typical head unit's power amp IC to full power you only need ~1/2 volt. Although that's enough for some amps, it's marginal for others. You could build a preamp but unless you're using this as a learning tool, it's better to use a line converter.

If you can find the datasheet for the power amplifier IC, it will tell you which pins are the input for the chip.

Bear in mind that one small mistake could be very costly. There are few repair centers for OEM head units and they have no mercy on you if the deck is out of warranty (going into it will void the warranty). Don't try to do this unless you can afford to repair or replace the unit.

johnm_10 · 7th April 2006, 08:54 AM

Ok, thanks for the reply. Sounds like it's going to be too much hassle; pity. Line converter it is.

6th April 2006, 10:59 PM	#1
johnm_10 diyAudio Member Join Date: Apr 2006 Location: Florida	Modifing stock head unit Just wondering if anyone knows of a guide somewhere that would help me modify my stock head unit. I want to add line out jacks. I think it would just be a matter of finding the correct solder positions on the board before the signal is amplified. Any ideas? Thanks

7th April 2006, 12:42 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the head unit doesn't have preamp level outputs, there may be no suitable signal in the head unit. The output ICs typically have high gain and therefore the signal they receive is typically very low. To drive a typical head unit's power amp IC to full power you only need ~1/2 volt. Although that's enough for some amps, it's marginal for others. You could build a preamp but unless you're using this as a learning tool, it's better to use a line converter. If you can find the datasheet for the power amplifier IC, it will tell you which pins are the input for the chip. Bear in mind that one small mistake could be very costly. There are few repair centers for OEM head units and they have no mercy on you if the deck is out of warranty (going into it will void the warranty). Don't try to do this unless you can afford to repair or replace the unit. __________________ Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links

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7th April 2006, 08:54 AM	#3
johnm_10 diyAudio Member Join Date: Apr 2006 Location: Florida	Ok, thanks for the reply. Sounds like it's going to be too much hassle; pity. Line converter it is.