Problem of blowing inline fuses
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=76986
Printed Date: June 06, 2024 at 5:53 AM
Topic: Problem of blowing inline fuses
Posted By: yayarea94fwb
Subject: Problem of blowing inline fuses
Date Posted: April 28, 2006 at 5:53 PM
Hello
I am having a problem of the inline fuse blowing that is coming directly off the battery.
A few days ago, all of a sudden the subwoofers stopped while I was driving somewhere. I popped the trunk, no lights or anything. Looked under the hood and the fuse was popped.
I replaced it and when the head unit powered up the fuse again blew almost instantly.
My car is a 94 Cadillac Fleetwood Brougham. The deck is Pioneer DEH-P6800. The subs are Sony XS-L121P5s (3), wired for 1 ohm, amp is Lanzar RB-HTG2600D (monoblock).
From a previous setup I had 50 amp fuses under the hood and for the first few weeks these worked without problem. After I blew a few sequentially, I tried purchasing 80 amp fuses -- when installed, they still blew, but the they shattered and scorched even worse than the 50 amp ones did.
Can anybody suggest what I can check that might be able to pinpoint my problem? Out of desperation I put the two ends of the fuse holder together and the RPMs dropped and everything. The capacitor went up to 13 or 14 (when it was at 0 before), but even then when I installed a fuse in the holder it blew momentarily. Forgot to say, I have a 2.5 farad capacitor. Now any time I install a fuse, it blows. Is there something I have to disconnect before putting in the fuse or what can be done? Thanks for any suggestions. Larry Ferguson
Replies:
Posted By: yayarea94fwb
Date Posted: April 28, 2006 at 6:16 PM
BTW, I used 4 guage power wire and ground wire for everything.
Posted By: haemphyst
Date Posted: April 28, 2006 at 6:19 PM
Where I would start is here (and you'll want a few 50A fuses for this... I suggest three): Remove EVERYTHING from the power cable. Replace the fuse, if it blows, you have a short in the power cable - simple. If not, add one of the removed components. If the fuse blows then, the last component you added is the defective one. Follow this trend, 'till you get to the last device. ONE of them will blow the fuse again...
Let us know what happens.
BTW, bypassing a fuse, even for diagnostic purposes is VERY dangerous. Try not to do that again, lest you burn your car to the ground...
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: yayarea94fwb
Date Posted: April 28, 2006 at 7:43 PM
Thank you so much for your prompt response. I don't know if this is good news or bad news (I think it is bad) but I bypassed the capacitor and put the wire direct to the amp and the same thing occured. As soon as the deck powers on (or within a second or two) the fuse blew out again under the hood (AGU fuse, BTW).
The thing is the power line looks completely fine and nothing has really changed since it was working well for the past few weeks to the present. There are no visible tears or frays in the red insulation part either under the hood, in the trunk, or under the drivers side carpet.
Let me know if you can lead me any further.
Thanks again.
Larry Ferguson
Posted By: forbidden
Date Posted: April 28, 2006 at 9:36 PM
Disconnect absolutely everything from the receiving end of the power wire. Black tape that end so it does not short. Now put a new fuse in the power wire. If it blows then there is indeed a part of the power wire between the fuse holder and the back of the car (where you taped the end) that is touching metal and shorting out. If it is not blowing the fuse at this point, it sounds like the amplifiers magic smoke that makes it work has been released. List exactly what is hooked up to the power wire and the size of the fuses in the amplifier(s). ------------- Top Secret, I can tell you but then my wife will kill me.
Posted By: yayarea94fwb
Date Posted: April 28, 2006 at 10:54 PM
Okay, just tried this. When the fuse is installed underhood without the back end of the wire inserted into the amplifier, nothing blows. Let me try and clarify. Even when it is hooked up to the amp or the capacitor and amp, the fuse itself is fine until I power up the deck. At this point, a second later when the amp would normally power on, no sound comes from the subs and upon a check under the hood the fuse is smoked.
I have the 4 guage power wire going from the battery (through the fuse holder) into the trunk, into a 1 -> 2 distribution block. One of the ends from the distribution block goes to the capacitor, which itself is grounded with a 4 guage wire. And the other end goes to the amp, which also is grounded with 4 guage wire.
The amp itself has (4) 30A green fuses.
Originally I was using a 50A AGU fuse in the inline holder under the hood. I upgraded that to 80A which I now have been using hoping that perhaps the 50 was not enough for my amp... but nevertheless no progress -- these 80A fuses seem to burn up even worse -- turning grey or black and even cracking the glass surround.
Thanks again for any information that could help. If there is anything else I can provide, please let me know.
Posted By: forbidden
Date Posted: April 28, 2006 at 11:28 PM
Problem 1, tab "A" does not fit into slot "B". 120 amps of fusing in the amplifier dictate a much larger wire than 4 gauge. It also dictates a much larger fuse than 80 amps. Again, disconnect the power wire from the amp entirely and retest. The amp may still be grounded by the mounting screws and the shielding on the rca cables. We don't want something bad to happen to the deck next do we? SO UNDO THE POWER WIRE FROM THE AMP. Retest again, If it does not blow then the problem is the amp. To me it sounds like the amp is shot, possibly from a bad ground or wrong impedence load operating on it. Read the grounding sticky for sure. We can give you all of the information in the world, it is up to you to use it if you want to. Realize please, that some of us are here to help and are highly versed in audio theory, fabrication and even life in general. That is the benefit of being older and in this business for so long. So my nice bold print up there is not designed to yell at you, just make you aware that you overlooked something that I said previous. ------------- Top Secret, I can tell you but then my wife will kill me.
Posted By: yayarea94fwb
Date Posted: April 29, 2006 at 9:43 PM
Thanks again for your replies.
I tried what you said -- fuse installed, end of the power wire taped with electrical tape -- does NOT burn the fuse.
The only reason I have a hard time believing there could be a problem with the amp is because it has only been used for 2 - 3 weeks! Furthermore, it never got as hot as any other amp I've ever used for my previous systems, so I definitely do NOT believe it was maxxed out or ever turned up past 1/2 to 2/3 power.
The worst part is I have had the amp for probably almost a year BEFORE I installed it -- long story, first nothing to put it in, then waiting for a deck and problems with mail order internet, etc., etc., etc. -- bottom line, I believe the warranty is up. But again I have only used this for a couple of weeks and nowhere closed to capacity. All the fuses on the amp are factory new, none are burned as well.
Thanks again, tell me if there's any additional information I can give you which will be useful.
Posted By: forbidden
Date Posted: April 30, 2006 at 1:01 AM
Usefull info, nope, bad news, yup. The amp has had it's day in the sun. This may have been from a bad ground or it may have just been a bad amp. Was it purchased from a authorized dealer or was it a refurb?
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Top Secret, I can tell you but then my wife will kill me.
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