Amp Repair ppl..Little help.

[edzy 10+ year member]

Thanks.

I appriciate your honesty. True, I have no experiance repairing amps.

But I am trying to get an idea whats involved. being as its an inexpensive amp, I dont mind toying around with it.

If some one said that the car wont start, I would say check

1. Gas

2. battery

3. carb

Thats all im looking for. 1,2,and 3.

If I check

1. fet,

2, PMW

3 diodes

Then I mite be able to fix it.

Thats all I was asking. What are the most common parts that fail.

Thanks to everyone that chirped in.

 

[dB-r 10+ year member]

Problem is there are different designs and special tools are required to EVEN CHECK the parts. Cannot be done so easily, that is why we have shops that do it that have the proper tools and experience. You need a good DMM, and an Oscilloscope. And a good understanding of what signals should be present in different places of the amp and know when you see something strange. It's just not that simple as to check things like if a car has gas in it, no way to compare, and you need specialized tools and training.

 

[edzy 10+ year member]

I hear ya.

Like newer cars need the pc to find codes and shit.

Im just messing around with it. If it doesnt work, then oh well I tried and will go from there.

If it was an amp worth value, believe me I wouldnt even mess with it.

But just for fun, why not.

Thanks.

imo, ppl who repair car amps are getting harder to find. Sure there some great companies like yours that have great rep, but theres very few local places. Even on the net theres either the manufacture, or the handful of companies that are spead out all over the state.

I know of one local place, but he is a old school tv repair place, and even he dosnt get many ppl asking about repairs. Most newer amps are almost disposable these days when they do go bad. (unless your talking some 2k+ dblock).

Thanks again for checking out this thread.

 

[dB-r 10+ year member]

No prob just trying to help you understand you can replace everything ithat "normally fails" in the amp and may still not find the problem. Might be a small not so obvious thing, which many times that IS the way it turns out doing amp repairs.

And yes I am fully aware of the lack of amp repair shops, that is why I got into this business, because I wouldn't have a whole lot of competiton and I had seen what other shops did and knew I could do 10 times better of a job of repairing peoples amps if I just put some actual "effort" into it rather than just trying to make a quick buck like other shady *** amp repair shops out there and it works for me. I turn away probably 50% of the people who call here wanting their amps repaired because there is more work than we (my 1 helper and I) can handle already at any given time.....

Alot of the TV VCR repair shops do a HORRIBLE job repairing car stereo amps.... they kinda know how they work but are missing some key things that make the difference from a good repair to an okay repair... We try to make every single repair we do a good repair, not just an okay repair. An repair that is just "okay" likely won't last you very long... We only do good repairs and don't have much of a warranty offering as a result of it because you never need it unless you are deliberately trying to blow the amp up after a repair (see SPL Comp guys, they are the reason we don't do much warranty, they would "kill" us on warranty repairs with their 18V setups running at .5 and even as low as .25 ohms....)...

 

[edzy 10+ year member]

I am just a hobbyist, so fooling around with this is just a learning experiance.

Ive learned a lot about amp guts just from the input on this thread and other posts you and others have made on amp problems. Also bcae and other sites cover some basic electronics.

But thanks again. Marc.

Ill post what the outcome is after the fet replacement.

"Alot of the TV VCR repair shops do a HORRIBLE job repairing car stereo amps"

I had a kenwood amp that the guy used some caps from an old tv, some fets from some other broken amps, and when i got it back, it would not shut off. Looked liked it was off but always was draining. My work around was to put an 80amp solinoid on the ground via a relay to make it work for a while.

 

[dB-r 10+ year member]

LOL, exactly the kind of thing I am talking about.... please people unless you are super desperate don't take your car audio amps to a TV/VCR type repair shop... Unless you KNOW they do good work on car amps from hearing other peoples experiences.....

 

[edzy 10+ year member]

 

[vingasoline 10+ year member]

that amp looks previously repaired by a blind man with a twitch.

I can't believe you pulled apart that transformer over a couple of blown fets!

for someone with limited experience, here is where I would start.

1. get a schematic, or at least find out if the part #'s are original and not just something somebody threw in there.

2. transistors are cheap (google utsource) replace all the power supply fets, and output transistors. Also, replace the pwm ic, if it's bad, it will blow a whole row of fets as soon as you turn it on.

3. check the gate resistors, they should be somewhere inline with the gate pins on the fets.

4. fix the horrible soldering job on the resistors and anywhere else you can find.

5. before you hook it up, check for a dead short between the pos and neg terminal, as well as the speaker outputs.

6. hook it up with a 10 amp fuse on the power wire just in case you didn't fix the problem.

I had the exact same problem with a soundstream tarantula. 28 mosfets, 32 output transistors, 1 pwm IC, 1 gate resistor = $70 and it works like new.

 

[gunz4me 10+ year member]

Lotsa luck in rewinding that transformer. You are going to need it!

 

[midnightg35x 10+ year member]

Yea, wow... why did you unwind the transformer? Did you keep track of the windings? If not, you're kinda screwed because the transformation ratio will be off. That can cause all sorts of other problems!

 

[Hotredpeppers]

Had similar problem, blew a couple of the 9710 Fets on the power supply.

How it started, just bought it, tried it out.... It would power up for millisecond then go into fault. While removing wires, I briefly touched the remote supply wire to the speaker connector next to it, after that it was dead totally. Changed all 9710's on the power supply after I Changed 4 of the 8 - 9805's on the other side of the board near the power connections . Now it will power up but no sound. No fault light , no protection light.

Suggestions?

Which IC is this that was mentioned that should be changed? If this has failed is it possible that the power would come on but not process the signal signal?

And gate resistors? Would they cause this too?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif