Fronts Stopped Working Totally

[MrNutter]

Hello everyone, this is my first post & question, so please be gentle. Forgive me for the novel I'm about to write but if you can wade through it & help me out I would very much appreciate it.

My old amp (sony xplode 600w 4ch) died the other day so I used that as an excuse to replace the amp & upgrade a couple of other components. I got another 600w 4ch Xplod as I was actually pretty happy with the last one & it lasted me for years. I also got a Pioneer 1200w sub in a ported box & a pair of 6.5" 280w Clarion component speakers. I put the new Clarions in my front doors & installed the wiring harness that came with them. I took the old Sony component speakers & thier harness & put them in the parcel shelf wired to my Sony 6x9's. None of the speakers on the back shelf are wired into the amp, only to the HU. The new Sub went into the boot using the existing wiring & the amp got bolted to the back of the sub box where the old one was & also using the old wiring (basically identical amps). The fronts use two of the amps channels & the sub is bridged over the remaining two, just like it used to be & as is recommended in the amp instructions.

I crawled into the back to adjust my gains & managed to set the fronts with no problem. As soon as I turned the gain knob for the sub though, my front speakers fell silent but the sub kept working. I checked the amp fuses & they are fine. I switched the RCA leads over & I had no sub & no fronts. This isn't looking good for the HU. Leaving the RCA's as they were I wired the front speakers to the subs side of the amp & the sub to the fronts side of the sub. Now I had fronts but no sub, so both sets of RCA's appeared to be working because both sets have either had the sub working or the fronts working. I'm thinking the problem is channel 1/2 on the amp. I switch the RCA leads back to thier original positions & leave the speakers as they are, now I've got a sub & no fronts again, so the sub is now working through channel 1/2. Now I'm really confused. After various combinations I have had channels 1/2 & 3/4 of the amp working & both sets of RCA's working, just not all at the same time. This leads to much cursing. After spending the better part of 18hrs fitting all this up & spending the better part of $600 on this gear, I wasn't very happy.

Does anyone have any ideas what the problem/s might be?

Thanks for taking the time to read this & thanks for any replies or opinions that might be offered.

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[kramer_212 10+ year member]

did you ever drop the rcas, on live power, your pre outs could be out on the stereo to

 

[MrNutter]

I havn't dropped the RCA leads with power on. I totally disconnected the battery (+ & -) to do the install & to do each change to the wiring afterwards. I'm going to see if I can get an old HU that I can hook up & see if that's the problem. Will probably take me a couple of days to hunt one down that won't cost me much though. I figured seeing as I've had a signal coming from both sets of RCA leads at different times that the HU is probably ok but I'll find another HU & make sure.

 

[MrNutter]

I'll see if I can simplify this so it's easier to understand:

I marked one pair of RCA leads with red tape.

Front speakers going through channel 1/2 on the amp, sub bridged through channel 3/4 on the amp. RCA with tape on left side other set on right side.

RESULT: fronts working but sub not working.

Front speakers going throgh channel 1/2 on the amp, sub bridged through channel 3/4 on the amp. RCA with tape on right side other set on left side.

RESULT: no fronts & no sub.

Sub bridged through channel 1/2, fronts through channel 3/4. RCA with tape on right side other set on left side.

RESULT: No fronts & no sub.

Sub bridged through channel 1/2, fronts through channel 3/4. RCA with tape on left side other set on right side.

RESULT: Sub working but no fronts.

I hope that helps & that people can offer an explanation for what I have happening here & what I can do about it.

Thank you.

 

[MrNutter]

Ok, this is really giving me a big headache & I'm about ready to rip the amp & sub out & set fire to them.

I borrowed an identical amp to mine & wired that up, I got the same results as I did with my own amp, so I felt it safe to rule the amp out as my problem. Today I borrowed another HU that I know works & wired that up. Things only got worse. Now I have no power going to my amp by the seem of it, the little green protection light isn't on at least. I checked the fuses, they are fine, triple checked my earths, they are good, checked all my connections, they are good & my battery voltage is fine to. Until I get power back to the amp, I can't diagnose if the problem is my HU or the RCA leads. The little red & black bands came off the RCA leads though & it is possible I had them mixed up when I first turned on the second HU (they were definitely in the right order before today). Is it possible that mixing up the RCA leads could have caused a short in the amp somewhere & that's why I don't have any power going to it?

 

[keep_hope_alive Premium Member]

sorry i didn't see this thread. gimme some time to go through your issue and i'll give you a good response with next steps and possible solutions...

 

[keep_hope_alive Premium Member]

i need the actual model number to verify a few things, but given it's an Xplod amp and from the use of the term "boot" you're in Europe, i can reference a newer model manual sold in the UK. Maybe the XM ZR604R?

http://pdf.crse.com/manuals/3214760111.pdf

verify the rear LPF and front HPF were off during your tests. having those on would make it difficult to hear when the signals were reversed. that amp is made to run a sub on ch 3/4 only.

your test requires that the wiring is perfect. you can only bridge on two specific terminals.

that amp (like most xplod amps) needs to have 4 RCA inputs in order to output on front and rear channels. I assume you have 4 channels of RCA since you mention you labeled one "rca pair" with tape. what is telling is that you get no output when "rca with tape" is on the right (rear). you only get output when the non-taped RCA is on the front (left) input, and only then do you get output on channels 1/2.

based on your tests above (and assuming all crossovers were off), i suspect a bad RCA cable (the one with tape) and bad 3/4 channels. since you tested a second amp, then i still suspect the bad RCA cable but also a wiring mix-up.

some head units have built-in crossovers. if so, then you'd need to defeat them as well to do the tests you described. having an HPF on the HU output would cancel with the LPF on the amp.

How to Test further:

you need a Digital Multi-Meter (DMM) that allows you to measure Volts DC and Resistance (ohms).

you should start by testing the wiring. use the DMM to measure resistance on the speaker wires (speaker wiring should be disconnected from the amp before testing.) simply measure between (+) and (-) and see if the readings make sense (all three pairs should measure between 3.4-3.6 ohms.

next test the RCA cables by measuring resistance between each end of each cable. measure between center pins on each end and then measure shield on each end (should have less than 0.6 ohms for both tests).

next measure between center pin and shield on one end (should have an open circuit).

after you've tested the wiring, report the results.

to verify power - use the DMM to measure DC voltage at the amp. measure both the amp battery connection and the remote turn on (when HU is on). both should read between 12-14VDC. do this test with speaker wiring disconnected. RCA's can be connected. a test light is not sufficient, you need to measure the actual voltage. use the amp ground terminal as the reference.

 

[keep_hope_alive Premium Member]

i compiled this pic from the owner's manual mentioned above. this should help with future discussions.