Hey guys, my brother in law's BOSS BA-4800 amp decided to blow (no suprise eh?) and thought i would have a go at fixing it. Opened it up but cannot seem to find any blown components.

The problem is, when we turn it on, it blows the fuse the second we turn it on. We replaced the fuse, it didint blow the fuse and stayed on, but no sound was coming out of it. We turned the deck of, then turned it back on and the fuse blew.

(when the fuse blows, the light goes green, when the fuse doesnt blow, it stays red so im not sure what color means protection mode)

Anyone have any ideas what it could be ? Its not a wiring problem because i threw my amp in his car and it worked fine.

EDIT: Something else that confuses the hell out of me, is that when the fuse blow, why would power still get to it for the light to turn on ? or is that from the remote wire ?

Thats a Handy little light called Protection..
If it is on, I would look at a Capacitor or short in the circuit board... look for little black area's


I know this is going to be hard to accept but, Its Boss.. When the Light is Red it should mean protection is on but it is BOSS so it could mean anything...

Just chuck it in the bin it is a waste of human resources to repair them


The cost of repair would be more then the cost of replacement..

Not meaning to sound negative or anything but I think it is Best to let it rest

Thats a Handy little light called Protection..
If it is on, I would look at a Capacitor or short in the circuit board... look for little black area's


I know this is going to be hard to accept but, Its Boss.. When the Light is Red it should mean protection is on but it is BOSS so it could mean anything...

Just chuck it in the bin it is a waste of human resources to repair them


The cost of repair would be more then the cost of replacement..


Yeah it came with his 300zx. I told him that they are POS's. He was powering his MTX 12" with it so atlease he can get something decent now.

It was feeding an MTX !! Ok I have a feeling that may have caused its death.

a Low quality Amp driving a Power Hungry sub..

never buy boss there crap! get pioneer.

use boss for a short period of time, untill you have sufficent funds to buy a better quality amp/s

use boss for a short period of time, untill you have sufficent funds to buy a better quality amp/s
Or just save up and buy a decent amp from the get go.

i was going to get BOSS amps.....they seem so cheap yet powerfull....

now that most of you have said :naughty: im thinking, well, for the same amount of money as a BOSS would set you back, what other brand could you get of a higher quality?

i don't think there is a brand as cheap, with better quailty,

i'll admit this, i'm running evyerthing of a 5 channel boss, ( pioneer tweeters and 6by 9's at the back and the 15in pioneer sub) have been doing so since mid march, i haven't had any problems with it, but the sound can get a bit nasty on hotter days,

look at it this way, it get's the job down, it provides the extra power, and it's cheap

i don't think there is a brand as cheap, with better quailty,

i'll admit this, i'm running evyerthing of a 5 channel boss, ( pioneer tweeters and 6by 9's at the back and the 15in pioneer sub) have been doing so since mid march, i haven't had any problems with it, but the sound can get a bit nasty on hotter days,

look at it this way, it get's the job down, it provides the extra power, and it's cheap

ok then ill stick with BOSS!
my budget is low, only bout 1.1K for EVERYTHING so some things are going to have to be budget....

meh

Get the Response Amps through Jaycar, they are Cheap and reliable...

I have a boss amp and havn't had any huge problems with it, a little problem with wiring but it's fixed now.

Yes your amp is going into protection mode, this may sound silly but did you d/c the speakers when you tried it again?

Are you using the right sized fuse for that amp?
D/c everything except for the remote, power and ground wire, does it still go into protection mode?
Sounds to me like there's a short somewhere, could be internal, but theres a good chance it's external (could be as silly as speaker wire touching bare metal).

yeah i removed all the speakers and it still did it. I even put it in my car and it blew my fuse. Strange thing is, its blowing the fuse at the battery but not the one on the amp.

The fuse at the battery is 60AMP and the fuse at the amp is a 60AMP.

yeah i removed all the speakers and it still did it. I even put it in my car and it blew my fuse. Strange thing is, its blowing the fuse at the battery but not the one on the amp.

The fuse at the battery is 60AMP and the fuse at the amp is a 60AMP.
Are you getting sparks or bright red connections? Sounds like the power and ground wire is connecting at the amp. I blew my fuse at the battery also due to me accidentally touching the ground and power wires together. Sounds like there could be a short in the power circuit of the amp, your wires are too close together or for some reason the amp is connecting the power and ground in a direct connection. I'd open up the amp and have a look for any pieces of excess metal around the power plugs.

I am getting a spark. Ill open it up again and have a look :)

Spark is bad... possible Shorted Circuit Board..
At least you havent had an amp dump current down your Ground wire making the point where the Amp is Grounded to the Chassis pour smoke out of it and Not Blow any Fuses !!

My First Elcheapo Amp did this..
So I left it on the Bench to safely Bench test it only to open the amp up and find a Large Spider cooked to the circuit board... Dont ask How it got in there as to this Day I still have no Idea..

Make sure there is nothing making contact between the speaker terminals. Eg loose wire . Clean all the terminals up. then test it with nothing plugged in. To see if anything goes astray.

Got a multimeter?

A good quick check to do with a multimeter is to set it to OHMS and check the terminals..

check your left and right channels (seperately)...

First check that you get a high reading (over 30kOhms) between your "-" right spkr terminal and "+" right spkr terminal. Do the same for the left. If you get a low reading (0-150 Ohms) then your pwr transistors are most likely stuffed (big expense, throw the amp out).

Second, check the "+" and "-" of each spkr terminal to the ground (or "-" from battery). You should get a high reading (at least 3kOhms) between each speaker terminal point and the chassis of the amplifier or "-" power terminal. If not then there can be a miriad of possible causes (throw it out).

Third, check the reading between the "+" power supply and "-" power supply. This should be high. A low or a short is bad!!!

If it is a short in the power supply you may be lucky... Check the closest diode to your power supply:

(may look a little different in your amp)
http://www.lavendergreenooaks.com/BEN/Dis one.JPG

(original picture)
http://www.polkaudio.com/images/highres/Car/Amps/Amp_CircuitBoard.jpg

now... if this diode has a low ohms value then remove it. Check to see if the "+" and "-" power now has a high Ohms value. If there is no change then the amplifier is most likely too far gone!!! If this is the problem then the amplifier should happily power up. The only problem is if you accidently wire it up wrong it will not be able to have protection.
I reckon that this is the most likely problem.

Now... if you don't have a multimeter and you've tried everything else, then I'd suggest you could take pot luck and remove this diode anyway (in a last ditch attempt!). Worst that could happen is it would blow another fuse!!!

Also notice in the outcut picture the capacitors (3 big silver things in the lower right corner) have a cross at the top. If any of these silver crosses are "bulging" out a bit,they may have shorted out and need replacing.


If the amp is still a no-go you could check that the RCA leads aren't shorting (test em like the spkr terminals).

Worst comes to worst, and if ya really love this amp, send it to me and I'll fix it for ya :D ( but if its not one of the problems mentioned its most likely to get expensive!!!)

I suggest that you change the fuse to a 5 amp rated one so you can test it without putting undue stress on the cables. I wouldn't put the 60Amp fuse back in until you know it will turn on without popping it.

Thanks for all that info when i get time ill check it all out. I tried taking it apart again but couldnt get to the other side of the board (solder side).

I checked the resistance between the + and - power and the resistance just keeps going up and up and up it doesnt stop :confused:

It also does it with the speaker terminals. Ill have another go at taking it apart later on.

@ magnat, thats pretty freaky I hate spiders but dead ones freak me out even more for some reason :confused: