1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

400 car amplifer needs to be repaired.

Discussion in 'Repairing Electronics' started by gary350, Nov 1, 2011.

  1. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    Someone gave my son a 400 watt car amp that does not work he was planning to throw it in the trash and kept the speaker box. I use to be an electronic tech 30 years ago, things have changed lots of things are not repairable these days. Before I let him trash it I wanted to ask, can it be repaired? If so what is the most common problem? Is it worth fixing?
     
  2. Sceadwian

    Sceadwian Banned

    Joined:
    Oct 27, 2006
    Messages:
    14,047
    Likes:
    141
    Location:
    Rochester, US
    There's a solid chance it's a capacitor, on the power side, but this isn't a garuntee, I wouldn't trash it anyways, there are components in there that probably still work, at least half of the power fets, if not all of them if it's a pre-amp or fuse failure. The cases are usually made out of high grade aluminum.

    Even if you're out of touch car amps aren't exactly high tech, crack the case open and take some pictures. If you don't see it right away, someone might be able to point the way.
     
    Last edited: Nov 1, 2011
  3. bountyhunter

    bountyhunter Well-Known Member

    Joined:
    Jul 17, 2009
    Messages:
    1,560
    Likes:
    81
    There has to be a high-current voltage booster to create higher voltage supply rails from the 12V source in order to get those power levels. I would bet dollars to donuts the power supply blew, and it is often an electrolytic capacitor (especially a switching cap).
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Sceadwian

    Sceadwian Banned

    Joined:
    Oct 27, 2006
    Messages:
    14,047
    Likes:
    141
    Location:
    Rochester, US

    bounty hunter.. you're asuming those power levels were real... Peak power in a car can easily hit that, not RMS though.
     
  6. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

    Joined:
    Aug 9, 2010
    Messages:
    5,484
    Likes:
    503
    Location:
    Vermont (GMT-5:00)
    I had a very similar problem with a 6-channel car amp some time ago. A friend of mine brought it to me and asked if I could figure out what was wrong, and if I could fix it. I opened it up and, sure enough, it was just a capacitor. There was a slightly burnt resistor, too, which may have been part of a chain reaction when the cap blew. Just look at the board and see if there's anything obviously wrong. I'd guess that 75-85% of the time, you'll see the main problem right away (at least that's how it's been in my experience).

    I hope you can figure it out! It's never a good idea to throw away electronics, whether they're working or not ;) I've even found uses for the old CRT monitors and TVs. Even if you can't fix the amp, don't throw it away. Chances are if you do, you'll find out a couple weeks later that you could have used components from it for something else :D Again, that's my own experience talking there....

    Good luck!
    Der Strom
     
  7. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    I checked the circuit board and there are no signs of anything burned, or anything that has been hot enough to change color. No capacitors splits open, blown top, or leaks. I have inspected every part and there is nothing visible wrong. Caps are all glued and soldered to the board I don't know what kind of damage I can cause by removing them to test them. Fuse is good. One more thing, its a 250 watt amp (not 400 watts like I was told) brand name Bazooka.

    Maybe I should connect it to 12 VDC, connect an input and connect the speakers and see what happens. I am taking someone elses word that it does not work but maybe they didn't have it hooked up right. I know some things like transceivers the power transistors COOK if you key the mic with no antenna will an amp COOK the transistors with no speakers connected?

    [​IMG]
     
    Last edited: Nov 8, 2011
  8. duffy

    duffy New Member

    Joined:
    Dec 22, 2008
    Messages:
    2,618
    Likes:
    73
    Location:
    nortern 'sconsin
    It's not going to cook, fire it up!

    I've worked in electronics repair departments and the most common problem is "NPF" - No Problem Found. You get the device in, and it works fine when you hook it up.

    Hook it up correctly, that is. Remember this amp is going to want to pull 20A. A little wall-wart transformer might not even be able to run this monster's switching regulator. Give it a +12V supply with some oomph.
     
    Last edited: Nov 9, 2011
  9. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

    Joined:
    Aug 9, 2010
    Messages:
    5,484
    Likes:
    503
    Location:
    Vermont (GMT-5:00)
    I agree. You're going to want to run this thing off an actual car battery. Perhaps you can work out a way to continuously charge it from mains so that it doesn't drain, but you're going to need the current capabilities of the automotive battery it was designed for. That is very important. If your battery can't supply enough current, the amp is going to look like it's completely dead.

    Der Strom
     
  10. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    I tested the speakers and the wire to the speakers it works. I wired the amp to the speakers and connected the input to a stero. I tested that and the input works. I connected 20 amp wire to the AMP then connected it to a 12 VDC 150 amp battery charger. Amp LED light is ON but NO sound.

    Speaker wire seems small it is only .040" diameter wire.

    The 12 VDC power terminal to the AMP has 3 connections, 12+, REM, GRN.

    WHAT is REM?????????????

    I looked online it says REM is connected in parellel with 12+ so I connected it like that.
     
    Last edited: Nov 23, 2011
  11. JimB

    JimB Super Moderator Most Helpful Member

    Joined:
    Sep 11, 2004
    Messages:
    6,329
    Likes:
    585
    Location:
    Peterhead, Scotland
    REMote control, at a quick guess.

    Two possibilities, put +12v into the REM terminal to turn on the amplifier,
    or
    connect REM to the 0v line to turn on the amplifier.

    JimB
     
    Last edited: Nov 23, 2011
  12. duffy

    duffy New Member

    Joined:
    Dec 22, 2008
    Messages:
    2,618
    Likes:
    73
    Location:
    nortern 'sconsin
    "REM" is for the "switched" +12V in your car. Fine to do it the way you have on the bench -

    - but not in your car. The reason they do this is so it won't run your battery down. You can't simply power the whole thing off the switched ignition +12V because now all the power for the amp would have to come through your ignition keyswitch, and it just can't handle it. So you have a heavy cable back to a fuse and the battery for the main power, and the amp detects if the car is "on" or not by monitoring ignition voltage through REM.
     
  13. Diver300

    Diver300 Well-Known Member

    Joined:
    Oct 19, 2007
    Messages:
    3,063
    Likes:
    101
    Location:
    England
    Some radios have an output which you connect to the REM input of the amplifier, so that the amplifier isn't on if the ignition is on and the radio is turned off.

    That output can also be called "aerial out" or similar because it can be used to power an aerial booster or to operate an electric aerial.
    It doesn't much matter if you run the amplifier the whole time that the engine is on as it won't use much power compared to what the alternator kicks out, but you do need to shut off the amplifier when the car is not running, or the battery will be flat within a couple of days.
     
  14. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

    Joined:
    Aug 9, 2010
    Messages:
    5,484
    Likes:
    503
    Location:
    Vermont (GMT-5:00)
    Most car stereo systems require a small amount of constant power. That is, connected directly to the battery. It's often used to keep clock circuitry running so it doesn't lose time every time you turn off your car. Usually it only uses a tiny amount of current, though, so it will not drain your battery very fast. However, REM stands for Remote, as I believe JimB suggested. I would assume that this is the trigger for any other amps you would have in the automotive. Basically, if you turn on the Amp, a small 12 volt signal would be sent from the REM wire into any other amps to signal them to switch on. If it is just this amp you're using, though, you do not need to connect the REM wire.

    Regards,
    Der Strom
     
  15. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    What is CHIL???

    CHIL is a 2 prong female plug with + and -.

    I went to online Bazooka 250W AMP ELA150.1 instruction manual and it is not even close. 4 outputs instead of 2. Also 4 battery terminals instead of 3. No CHIL. Several other things are not correct.

    I went to online Bazooka Speakers Model ELW1014P it says. Speakers are 4 ohms 250 watt RMS each 500 Watt Peak notice wire polarity + and - speakers must be wires correctly to the + and - terminals on the AMP.

    Amp instructions even thought it is not the correct 250W amp says, TWO 4 ohm speakers in parallel = 2 ohms. TWO 4 ohm speakers in series = 8 ohms. When connecting 4 speakers, Warning do not connect a load less than 2 ohms to the AMP or it will cause perment damage to the amp.

    The speaker box has only 2 speakers they are wired in parallel = 2 ohms.

    Online wiring instructions and all different. One shows connect REM to +12 VDC. Another place says connect REM to the output teminal of one of the car radio speaker wires. Some circuits are confusing REM goes to a control box but no information how to wire it or what it is. Some circuits do not show REM. Some circuits show REM as 2 terminals with a ON/OFF switch.

    There are 3 controls on the AMP. According to online infor LEVEL is the input signal from the radio. X-OVER adjusts from 40Hz to 130Hz. BASS BOOST is 0dB to 12dB. What is BASS don't they mean BASE?

    SPEAKER output terminals are only made for 2 wires.

    Now I am wondering if this is a BASE only AMP. Maybe it is not designed for music. Maybe another AMP and speakers are required for the music???

    Input music has plenty of BASE but the speakers act like they are not even connected. NO sound at all.
     
    Last edited: Nov 24, 2011
  16. duffy

    duffy New Member

    Joined:
    Dec 22, 2008
    Messages:
    2,618
    Likes:
    73
    Location:
    nortern 'sconsin
  17. cr0sh

    cr0sh Member

    Joined:
    Jul 10, 2010
    Messages:
    928
    Likes:
    17
    Location:
    Phoenix, Arizona
  18. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    I think maybe this AMP is dead.
     
  19. duffy

    duffy New Member

    Joined:
    Dec 22, 2008
    Messages:
    2,618
    Likes:
    73
    Location:
    nortern 'sconsin
    Get in there and take some readings. Those big electrolytics are almost always conveniently on the power supply rails. Even with a 2Ω load, you are going to need close to 30V to get 400W out of it, you should see either the that across both caps, or +/- 15V for a bipolar supply (probably the former, L1 looks like the lone filter coil).

    The power supply is where you start. If that's ok, you trace the input signal through as far as she goes. Going to need a schematic for this at some point in that proceedure - but if it comes to it, you can draw one yourself.
     
  20. kylemaes

    kylemaes Banned

    Joined:
    Nov 20, 2011
    Messages:
    36
    Likes:
    0
    Kids like to crank theese things on first glance Id say the mosfets are gone! If one is gone nothing works...
     
  21. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    Hello Gray350... it's ok to use a car battery charger to work on your amp plus a current meter aswel.. car amp have dc to dc converter pwm psu.. the o/p amp runn's on say 25+/- dc at the collectors these are just standard power transistors...check for dry solder joins cracks.. if you have a scope/gennie even better to trace to the fault...
    ...just link the remote via a 10 ohm resistor to the plus and repower up...try this site for more information Basic car amplifier electronics....
     

Share This Page