car amp repair man.....

[theMessenjah44 10+ year member]

I was talking to a guy today here in my town(St.Louis) and he told me to let everyone know who I am and what I do.
I am a old school SPL'er from the late 80's back when a amp rated at 50 watts per channel for some mysterious reason needed 0 guage battery cables just to power up and would melt my subs into a messy puddle in my sub cabinet...Those were the days...Back when 1/2 ohm stable was expected and put to the test every day just driving back and forth to work.

I never could get enough...it was never loud enough...I remember when the solobarics first came out..I managed to get ten-10's in my trunk and put a bridged d-200 soundstream (modified) on each one....didnt get any wins...I did however manage to piss everyone who lived within a half mile of me off for about 3 months!...I just couldnt seem to turn it down....My old 72 cutlass....I put so many different systems in there that everywhere I went people would crowd around just to see what I was running that week. I worked at a couple of the showcase shops around town and got stuff either really really cheap or just got to throw the newest stuff in the car to show it off and try it out.I remember when the Alpine7618 first came out..We were one of a very lucky few people in town who sold Apine back then...and I got to put one in my car...mind u this was a cassette deck..with a din cord 6 disk changer option but I still pretty much slept in the car for a week or so just so I could be close to it...

I started fixing amps when I was too young to even drive a car..I was building them by the time I was I think 14 or so...I'm now 42 and Im still at it.

The car audio world has been great to me over the years. I do work on home and pro equipment too...but love the raw power and brutal current draw of a car amp...I only work on amps....

There are some nice amps out there hiding masked over as junk...Everyone knows the name pyramid right? I know..I should be ashamed for saying the word..But did u know that at one point the american series were made by ZED AUDIO and are extremely modifyable?...you can double the output of those things! and they were sweet sounding too.I remember the first one I ever took apart I was so stunned when I saw what was inside that thing...I immediatly went on a mission to make all my friend sick with what I could do with a bunch of pyramids...the Hifonics series 7 and 8....Thats when Hifonics was a force to be reconned with...Man you could jump start a car with a series 7 Zeus and of course the original power series from rockford....the power 300 was one of the best sounding amps out there and the 300 watt rating was just insane...that thing right out of the box was puttin out on average 165 per channel at 4 ohms-times 4 channels..and the math got blurry.. and if that wasnt enough...drop it down to 2 ohms and it would almost double and you still had the option to bridge it-add a handfull of higher voltage higher current fets and play with the P.W.M. timing and duty cycle in the power supply and you had some serious power at ur command...course..it pretty much eliminated any sort of warranty....

Anyway..I still love to talk about it....

I'm in the process of setting up new shop and Ill be able to handle more business and Id like to offer my services to you guys...

I work at home so I can keep cost way down.I dont depend on it for my survival...but life wouldnt be any good without it..I love workin on amps and I know first hand how bad it feels to be flyin down the road and have a amp die...or just have the car fill with that nasty smelling smoke...my 280z filled with smoke one day and I thought it was on fire...just my alpine on its way out....and if your anything like me..it happens. 4 tens in the back of a 280z on a single bridged alpine is a no-no but I had to try it-according to alpine u cant bridge one and run it at one ohm..I just wanted to make sure though...

Im not ready to start takin amps in yet..I just moved to a much bigger place and Im gettin set up.Im thinkin right after christmas Ill be ready to go..

I just wanted to introduce myself and see whats going on here and Ill try to get on once every day or two and maybe answer some questions if anyone has any and get to know some people...

That's a long post you've got there.....//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[2lo2flo 10+ year member]

Welcome! There's always a need for good amp repair guys.

You have to prove yourself first though, maybe pics of your work? Or more recommendations?

Good luck bro!

 

[amprepairman 10+ year member]

to TREY 803....

I cant fix a amp over the internet! I can tell you a little about power supplies though..

Someone mentioned that the 2 amps posted under my post looked like fet failures...they were right...Virtually all amp failures either start or end with a fet or transistor failure....

I allways replace all the fets in a power supply when one fails...In some amps this can get expensive but the past has taught me that its the only reliable way to do it.

In the pic Trey posted u'll allso see R40 and R42...those are whats called a "gate resistor" and there should be one for every fet in the power supply..they are usually 10 to 100 ohms but should allways match and be checked in any power supply repair

On the fet's....A good manufacturer in my opinion is Intenational Rectifier- on any fet they make they use "IRF" as the beginning of thier part number

the IRFZ44 is a very common mosfet found in power supplies usually the 44 will be followed by a alpha character such as a "v" I.E. IRFZ44V and the letter following the 44 does matter its a version number and there are many versions of the Z44...however there are alot of copies out there from various lets say "over seas" companys they will be that companys letters followed by the 44...they seem to self desrtuct pretty easy. The KIA44 is a common one made in korea...its like going to auto zone for car parts...they are ok but not what u want to depend on when ur toolin down the highway at a casual 140 m.p.h....(that was one pissed off cop-he threw me in jail and towed my G.T.A.)

If you google IRFZ44 and get on a web site for a IR distributer u'll find a wide array of fets that will fit in the same space as your current ones...(TO-220 case style)higher voltages and higher current capabilities with low on state resistance. This is where a good tech with lots of experience comes in handy...to understand technical data and in my case to have tried a million combinations over the years using my amps as crash test dummies...The same applies to your output section of your amplifier section and doesnt matter if ur running fets or transistor outputs...its just a matter of matching components that will work in your application.

Back to the power supply...In the same pic I mentioned before....U'll see a little I.C. surface mounted...It a TI494 TI being Texas Instruments chip designation. That is a pulse width modulator and its the most common one used on the planet earth (there are some aps that run a TI594 which is basically the same but monitors current instead of voltage to regulate the power supply)...anyway...it controls the speed and duty cycle of your power supply (its job is to monitor rail voltages and run faster or slower to keep the rail voltages the same at all times depending on load conditions)...and it can be under the right conditions changed around to give u more power.The changes are external to the chip as far as operating speed and duty cycle which are regulated by a combination of parts that monitor your rail voltages that supply your output transisters or fets...Higher voltage with the ability to carry more current= more power output...and we all know what that is....(in order to get any serious voltage gains a higher voltage transformer must be installed or yours needs to be pulled and rewound so u'll have a fit that looks stock but puts out higher voltage)...one of those old school tricks that guys used to do in low watagge classes.

Im not sayin you should start doin mods to your stuff..Im just saying that there are many many options out there that people have been doing for years to give them the edge over the competition

So if your gonna try to fix your own power supply issues...First replace ALL the fets....then check ALL the gate resistors and replace any that arent right...At this point things get a little sketchy for the non tech type guys...theres a 50/50 chance its fixed with that but if not...its either one of the transistors that drive the gate resistors called a totem pole driver...or the TI494 itset has cooked or of course you could have a down stream problem...also when mounting new fets make sure you clean up the heatsink very well and get all the little blown up pieces out of it before you remount the new ones allways use new clean heat sink compound and make sure your isolation washers dont have any holes in them(thats the little pieces of plastic between the fets and the heat sink)

I could go on and but but Its allready been mentioned that I might post a little to long.....so..thats MosFet 101...

The electronics in your amp is just like a chain..when its gonna blow up the weakest link goes first...so if your having the same problem over and over its time to modify it if you really like the amp and want to keep it in your set up.

I hope that halps you guys a little....

 

[2003F150 10+ year member]

Good info here

 

[Louisiana_CRX 5,000+ posts]

Glad you made it to the forum...theres a lot of old school guys here ...I may need some repairss myself in the future....

 

[djarmy2004 10+ year member]

Glad to have you hear and hope it works out for u. You will surely see alot of people bag on u though, thats just part of ca for some reason. WELCOME

 

[chardy85 10+ year member]

Glad to have you hear and hope it works out for u. You will surely see alot of people bag on u though, thats just part of ca for some reason. WELCOME

lol

Yeah I told him he will probably meet some really cool old schoolers and other people but some people on here he will just have to learn to ignore.

 

[microhaxo 10+ year member]

Nice to have knowledgeable people on here, welcome!

 

[Spooney 10+ year member]

i'd like to add a little something to what amprepairman said. Blown fets in the power supply more often than not go hand in hand with blown fets in the output section of your amp. a good indicator of where the problem lies is when your fuse blows on the amplifier. if you have an amp that is blowing fuses when remote turn on power is applied then it is a good chance at least one of your output fets are toasted. if your amp is blowing fuses the second you replace a fuse or hook up your power wire(no remote turn on signal applied) then you are probably looking at some power supply issues. I just wanted to add this because I wouldn't want somebody to think just because they replaced some blown ps fets that their amp is as good as new. It is fairly common for a fet to die without any visual signs of destruction. You will need to get in there with your multimeter and check for shorts between the legs of the fets.

 

[thehardknoxlife 10+ year member]

I still wanna see pictures of your work. Do that and I'll be the guinea pig.

 

[dbman150 5,000+ posts]

when you are ready i have a massive audio 1500.1 i need fixed

 

[brmcm15 10+ year member]

very nice post man.

lot of info.

i would also like to see some of ur work

and may need some repairs in the future too! lol

welcome

 

[amprepairman 10+ year member]

ok...

I am waiting for some amps to come in from a deal I got on Ebay where I buy up broken amps...Which by the way Im allways lookin for....

When they get here I'll look through them and see if any of them are good for a highly modified type build...Updating everything possible for reliability sound quality and performance..And once I decide which one to build..I'll post what I'm doing with pics step by step...

It wont be a fast process because I have to put my customers ahead of it..but everyone will be able to see whats going on step by step and see the results when its done...

If you have a amp you would like repaired..send me ur contact info along with the make and model number of the amp were gonna be talking about to:

amprepairman@caraudio.com

Ill get ahold of you and we'll take it from there

 

[fast306stang 10+ year member]

amprepairman--email sent!

 

[amprepairman 10+ year member]

I can be reached at:

ifixamps@yahoo.com

314-707-7327

THE SERVICE...

I try to answer service related questions same day..if you send me a email....

Once I have a amp in for service turn around time provided I have the parts is right now running 7 business days maximum.

I accept payment through pay pal only.

I can't release a amp until it is payed in full.

I do not charge a up front fee however if for whatever reason you do not get your amp repaired and you want it back...

You will have to pay full shipping cost before I can return it.

I charge a maximum of $15.00 to ship anywhere in the united states on all amps I repair.(subject to change).

I only accept amps coming from the united states for repair at this time-if you are outside the country call and we can talk

about it.

I contact you if the repair is going to be over $80.00 and that is including the 15.00 max shipping return charge.

I will consider working on any amp...I will need make model and a description of the problem to the best of your ability

before I will have you send any amp in for repair.

I usually ship through priority mail(if it fits it ships) and UPS

THE PROCESS...

You ship the amp to me...

You send me the tracking number as soon as it is shipped...WE CAN'T ACCEPT ANY PACKAGES THAT WE DO NOT HAVE A

TRACKING NUMBER FOR!

I send you a invioce number as soon as I recieve your amp...which will be used for all communications about your amp from

that point forward.

I either fix your amp or I send you a estimate.....see estimate details above...

I will send you a invioce to your email adress...when its payed I'll send your amp back to you....

Paypal will send you a reciept....Allways hang onto invoices..(I might be famous some day and it'll make your amp worth more)

As soon as I ship your amp I'll send you the tracking number to your email adress....