Hey all,
I've had the MTX Audio RT8PT (powered subwoofer) installed in my '01 Subaru Outback for a little over a year, working flawlessly. Recently, it does this annoying thing where only plays once every 5.5 seconds. Upon inspection, the Thermal Protection light on the sub's integrated amp is illuminating when it is not thumping. The Owner's Manual does not offer any help other than telling me it is in Thermal Protection mode.
So something is causing it to go into protection mode every 5.5 seconds. Very weird that it's so periodic.
The sub +12V Power is connected to the vehicle battery (fused), sub Ground connected to unpainted chassis 1 ft away from where sub is mounted, and remote turn-on is wired from the OEM headunit power antenna signal. Audio signal is coming from OEM headunit>PAC SNI-35 Line Out Converter>RCA Cables plugged into sub.
Something Interesting: If I only unplug the RCA cables from the sub, the speaker stops going into Protection Mode and remains powered on.
Things I have inpected/tried:
This is driving me crazy. Especially when sometimes the sub starts working normally for a few minutes then cuts back to its erratic behavior. Any things to check? I am a noob when it comes to tracing circuitboards with a multimeter, but maybe this is a good way to learn.
Thanks for reading!
I've had the MTX Audio RT8PT (powered subwoofer) installed in my '01 Subaru Outback for a little over a year, working flawlessly. Recently, it does this annoying thing where only plays once every 5.5 seconds. Upon inspection, the Thermal Protection light on the sub's integrated amp is illuminating when it is not thumping. The Owner's Manual does not offer any help other than telling me it is in Thermal Protection mode.
So something is causing it to go into protection mode every 5.5 seconds. Very weird that it's so periodic.
The sub +12V Power is connected to the vehicle battery (fused), sub Ground connected to unpainted chassis 1 ft away from where sub is mounted, and remote turn-on is wired from the OEM headunit power antenna signal. Audio signal is coming from OEM headunit>PAC SNI-35 Line Out Converter>RCA Cables plugged into sub.
Something Interesting: If I only unplug the RCA cables from the sub, the speaker stops going into Protection Mode and remains powered on.
Things I have inpected/tried:
- Fuse on both amp and battery connection are intact and read nearly 0 Ohms
- Ground connection to chassis is clean and tight
- Woofer rated at 4.0 Ohms, measured 3.8 Ohms
- 12.4V between sub Power and Ground terminals with car off, 14.3V with car running. When in thermal protection mode, voltage does NOT change (MTX Tech support said this is expected behavior)
- 11.7V between sub Remote-On and Ground terminals with car running (MTX Tech Support said it should work with >10V)
- All connections tight and clean behind headunit, on battery, and to sub
- Followed all wires, no shorts or broken insulation
- Changed OEM headunit Fader, Balance, and Bass settings in many combos, with no luck
- No loose solder joints or bulging Caps
- Tested for continuity between RCA jacks and their respective internals (seems perfect)
This is driving me crazy. Especially when sometimes the sub starts working normally for a few minutes then cuts back to its erratic behavior. Any things to check? I am a noob when it comes to tracing circuitboards with a multimeter, but maybe this is a good way to learn.
Thanks for reading!
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