the item in question is a pioneed cd player, mdl# deh-p3500 with mosfet 50w x 4. I have had a problem with my subs shutting off after 5 min of hard thumping, I have checked every possible thing except the HU. I checked it today and noticed that the actual unit was warm and the heat sink was extremely hot, I am wondering if my HU is over heating causing the some type of failure resulting in the subs shutting off. If i turn off the HU then back on the subs play again, the amp is warm but nothing alarming. Could this cause the problem if so how can it be corrected?
Replies (10)
Swez on 09/13/2003 18:46:51
Some HU's do run a bit warm when they are pushed hard, but if the HU gets too warm, some of the amplifier circuits may cut off to cool, then come back on. Do all channels go out along with the subs or just the sub/amp combo only?
This HU has some nice features and I note only F&R RCA outs for additional amping. Are you using the RCA's or tapping from the rear speakers to feed the sub amp?
What amp & subs are you using now? How are the subs wired to the amp?
Swez
greg311 on 09/14/2003 00:48:27
I am using the RCA's to feed the sub, the amp is an alpine mrp-m350 vseries class d mono amp, I am using 2 mtx road thunder 12's 4 ohm speakers and they are wired in parallel. With this wiring I believe they are getting 175watts rms at 2 ohms a piece. I changed out the RCA's and changed the ground it and it seems to happen less often but it still happens. I have checked everything possible and am completely stumped. I have the front and rear speakers wired directly to the HU and only the subs cut off not the other speakers, again I turn the HU off then on and the subs start playing again and from past experience the amp dosent seem to be getting that hot. The amp never shuts off or goes into protection just the subs quit playing.
greg311 on 09/14/2003 01:27:21
originally I had 2 mtx blue thunder 12's 4 oh wired in parallel with the same HU and amp and it did it, I exchanged the HU of the same model for a new one and did the same with the amp also I bought the mtx road thunders and still did it. It was to be something with the HU or a ground either with the HU or amp, thats what I am getting by just trial and error.
Swez on 09/14/2003 07:31:56
Interesting... one of the key aspects of a good install is getting a solid "BARE METAL" ground for the amp and HU. If the ground is not consistant, problems often arise.
When the HU was installed, did they (you) install a factory harness ground or take the ground directly to bare metal floor pan? If you used the harness ground, try grounding to the floor pan near the HU and see if that improves the situation. Same with amp... bare metal ground to body pan.
Swez
PS FAQ Help topic: http://www.clubknowledge.com/Car_Audio_FAQ/?t4
greg311 on 09/16/2003 10:38:39
Ok, I disconnected the ground wire to my HU to relocate it. In the process something else came up so I stepped away for a couple of hours. I came back and I turned on the HU with NO ground wire connected and my system played. Someone told me that this shouldnt happen, that the HU shouldnt play with no ground wire, it was suggested to me that it is possibly grounded elsewhere, is this true and how?
ttocs on 09/16/2003 11:23:06
are you still running 2 12"s off the deck? If so then you have your problem...
greg311 on 09/16/2003 11:47:19
yes, the 2 12's are running off the HU via RCA's so you think that I have a grounding issue relating to the HU?
ttocs on 09/16/2003 17:14:47
are the subs hooked up to an external amp?
Please say yes......
greg311 on 09/16/2003 17:21:49
yes, subs are connected to external amp via the traditional speaker wire and subs connected to HU via RCA's.
Swez on 09/16/2003 17:50:51
The RCA's are providing a psudo-ground from the amp back to the HU. It's not a suitable ground, but this is why the HU still works. Try unplugging the RCA's from sub amp and I would bet it may still play as the antenna is also part of the ground left in your HU... not good enough... need a solid bare metal ground at HU as well. Poor grounds can make an amp or HU run hot. Too much internal resistance on the power line/ground path will cause the device to work harder (starved for voltage) and draw more current... hense, more heat. Excess heat in any electrical device is the major cause of failure of a device. Excessive low ohm loads will also make the HU run hotter. Any extra speakers wired to this HU?
Also, where is the gain control set on your amp now and how many volts of RCA signal are available in this HU? Nevermind... I looked it up... 2.0 volts. So, your amp gain should be set pretty close to 2.0 volts (+/- 1/2 volts). If the gain is set too high (under 1.0 volts) the amp may shut off for a time and then come back on again.
Check that setting and redo the ground and then tell us what you have... hopefully a stable system, cooler running HU amps and subs work all the time.
Good luck,
Swez
Replies (10)
Swez on 09/13/2003 18:46:51
Some HU's do run a bit warm when they are pushed hard, but if the HU gets too warm, some of the amplifier circuits may cut off to cool, then come back on. Do all channels go out along with the subs or just the sub/amp combo only?
This HU has some nice features and I note only F&R RCA outs for additional amping. Are you using the RCA's or tapping from the rear speakers to feed the sub amp?
What amp & subs are you using now? How are the subs wired to the amp?
Swez
greg311 on 09/14/2003 00:48:27
I am using the RCA's to feed the sub, the amp is an alpine mrp-m350 vseries class d mono amp, I am using 2 mtx road thunder 12's 4 ohm speakers and they are wired in parallel. With this wiring I believe they are getting 175watts rms at 2 ohms a piece. I changed out the RCA's and changed the ground it and it seems to happen less often but it still happens. I have checked everything possible and am completely stumped. I have the front and rear speakers wired directly to the HU and only the subs cut off not the other speakers, again I turn the HU off then on and the subs start playing again and from past experience the amp dosent seem to be getting that hot. The amp never shuts off or goes into protection just the subs quit playing.
greg311 on 09/14/2003 01:27:21
originally I had 2 mtx blue thunder 12's 4 oh wired in parallel with the same HU and amp and it did it, I exchanged the HU of the same model for a new one and did the same with the amp also I bought the mtx road thunders and still did it. It was to be something with the HU or a ground either with the HU or amp, thats what I am getting by just trial and error.
Swez on 09/14/2003 07:31:56
Interesting... one of the key aspects of a good install is getting a solid "BARE METAL" ground for the amp and HU. If the ground is not consistant, problems often arise.
When the HU was installed, did they (you) install a factory harness ground or take the ground directly to bare metal floor pan? If you used the harness ground, try grounding to the floor pan near the HU and see if that improves the situation. Same with amp... bare metal ground to body pan.
Swez
PS FAQ Help topic: http://www.clubknowledge.com/Car_Audio_FAQ/?t4
greg311 on 09/16/2003 10:38:39
Ok, I disconnected the ground wire to my HU to relocate it. In the process something else came up so I stepped away for a couple of hours. I came back and I turned on the HU with NO ground wire connected and my system played. Someone told me that this shouldnt happen, that the HU shouldnt play with no ground wire, it was suggested to me that it is possibly grounded elsewhere, is this true and how?
ttocs on 09/16/2003 11:23:06
are you still running 2 12"s off the deck? If so then you have your problem...
greg311 on 09/16/2003 11:47:19
yes, the 2 12's are running off the HU via RCA's so you think that I have a grounding issue relating to the HU?
ttocs on 09/16/2003 17:14:47
are the subs hooked up to an external amp?
Please say yes......
greg311 on 09/16/2003 17:21:49
yes, subs are connected to external amp via the traditional speaker wire and subs connected to HU via RCA's.
Swez on 09/16/2003 17:50:51
The RCA's are providing a psudo-ground from the amp back to the HU. It's not a suitable ground, but this is why the HU still works. Try unplugging the RCA's from sub amp and I would bet it may still play as the antenna is also part of the ground left in your HU... not good enough... need a solid bare metal ground at HU as well. Poor grounds can make an amp or HU run hot. Too much internal resistance on the power line/ground path will cause the device to work harder (starved for voltage) and draw more current... hense, more heat. Excess heat in any electrical device is the major cause of failure of a device. Excessive low ohm loads will also make the HU run hotter. Any extra speakers wired to this HU?
Also, where is the gain control set on your amp now and how many volts of RCA signal are available in this HU? Nevermind... I looked it up... 2.0 volts. So, your amp gain should be set pretty close to 2.0 volts (+/- 1/2 volts). If the gain is set too high (under 1.0 volts) the amp may shut off for a time and then come back on again.
Check that setting and redo the ground and then tell us what you have... hopefully a stable system, cooler running HU amps and subs work all the time.
Good luck,
Swez
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