An update for the 240sx SE Factory Amp Bypass FAQ

[DanCouga]

I got bored and went sunday shopping today and picked up a new head unit for the 240. When I got home I figured I should go ahead and bypass the factory amp. I read the FAQ posted on 240sx.org and was kind of dissappointed, no offense to the original author. So I figured I would go ahead and try and update it a little.

My method is a 'no turning back' method. The original method you could probably splice back in the factory amps if you needed to, for mine to work you will have to be a little destructive and remove the connector from the amp.

Step 1 was of course drawing up the schematic, which wasn't hard at all, the board is laid out fairly well and most things are labeled.

We'll start with Amp 1(the one with the larger connector). You have 15 pins(3 of which you will never need ever again. ever). You have an input for left and right and two outputs for each. This number is higher than the original FAQ because it did not include information on the pillar mounted tweeters. Once you have written down what each pin is and desoldered the connector from the board, you'll need something to put it in. You can get a small solderless bread board or a blank circuit board. All connections will be left to right, top to bottom while looking at the connector with the longer pins on the top. You should have 3 long pins and then a gap of 2 blanks and then another set of 4 pins, the bottom row should have a group of 6 pins with 1 blank followed by 2 pins. You need to jump 1-3-6 for left + and 8-10-14 for left negative. 2-7-12 for right + and 9-11-15 for right -

That's it. The other wires on this connector are power, ground and the remote wire.

I'll post the second half once the nyquil I'm drinking wears off.

[PoorManQ45]

I'm wondering, did you use the OEM speakers?

If not, then why did you go through all that trouble? You could have just run completely new wiring.

[DanCouga]

Yes for right now I am using OEM speakers. And no it wasn't any trouble, relatively easy if you ask me.

Eventually I will install a multichannel amp and new components, at which time I will run new wiring.

And when you think about it, new wiring would have been more trouble than this. I was able to do this inside an air conditioned room and not sitting out in a car in the sun

[Silvia2b]

I think PMQ was referring to the fact that the factory wiring is so small, like 20 gauge or so. Plus you have tons of excess length to induce loss of signal. Think about it. You have wires that run from your head unit to the trunk loop around and then head back up to the front speakers. All of this with the tiny factory wiring. Unless there was something wrong with the factory amp you would have been better off soldering on RCA male connectors in the dash to an aftermarket female harness to put your deck in and retain the factory amps.That way you don't have to parallel the factory fronts speakers and run the rear 2 ohms speakers off the deck which could case it to overheat with the low impedance of those drivers. Do you see what I mean. I congratulate your efforts, the time may have been better spent running new wire or making the RCA connections in the dash. If you plan to upgrade soon anyway the factory harness for speakers and amps will be useless. But it looks like you enjoyed doing it anyway, thanks for sharing with us. I always like to hear stories about other peoples projects.

[DanCouga]

Yeah it was something to do while I was stuck inside with the flu(or something just as evil). I managed to sneak out to pick up the headunit but returned home as soon as the meds started kicking in. I didn't even think to check the ohms(or I might have thought about it and just forgot to do it ). This weekend I'll be installing the amp and running new wiring. I've got a stack of speakers from when I had my Jeep and figure I might put some of them to good use.

[Silvia2b]

Cool well I hope you get over the sickness I had something similar for weeks it was awful. Once you are then get to putting that JL stuff in your car where it belongs instead of in the box. Keep us posted we’d like to see your results.