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
    The way this amp is built it will take me 45 minutes or more to get the circuit board out of the aluminum case. It will take at least the same amount of time to put it back. If spend an hour or 2 trying to find the problem then I will have maybe 3 or 4 hours work in it with a 50/50 chance I find the problem in a short time. A new amp only cost $55 on ebay, my time would be better spent doing something else and not wasting it on this amp. It would be a fun challange to find the problem and fix it but at the moment I just don't have the extra time.

    I think I will throw the amp in the scraps parts pile for now.
     
  2. 4pyros

    4pyros Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2010
    Messages:
    4,368
    Likes:
    282
    Location:
    Pennsylvania, USA
    Na, maybe 10 -15 minutes. Take the end plates off and just a few screws holding the chips to the heat sinks.

    I would see if it even powers up 1st. The REM connection is the remote turn on. It must have full 12 volts to turn the amp on. It is usually hooked up to the power antenna output of the stereo head to turn the amp on and off.

    The power supply in the amp should be a switching power supply to get the voltage up to around 40 volts or so. check for a high voltage on the dual jumper wires by the big wight resisters.
     
    Last edited: Jan 12, 2012
  3. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    looking at the picture I can see the main filter caps just to the left of the transformer...2200uf what voltage is on these? may 35 or 50voltalso this amp is of lowish power as the power o/p's are to-220's say 6amps each...here's a quick test...power up and check the voltages small op-amp at the front end there 8pin types..pin 4 is - say 12 or 15 volts and pin 8 is the + pin.. just standard op-amps...there's 3 of them...

    The pain in the neck so to speak..it's the so call lead free solder that's used as it look's dry jointed just re-flow with 60/40 solder..
     
  4. dave

    Dave New Member

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


     
  5. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow

    does the power up led change from red to green? or stay red..some amps are fitted with a bi-colour led that will start red followed by green aso the protection circuit does a check... have you tested the o/p with no load...there should be low dc volt's below say 50mv..and 0 AC volts.
    apply in signal and recheck o/p your meter should raise up on ac settings... if need be you can inject a signal to the main power stage via a jack plug fitted with a 10k level pot to trace that stage.. just think of it this way...power supply-- pre-amp stage then main amp stage..
     
  6. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    I took the amp apart it only took about 10 minutes.

    I tested all the capacitors they all test good on the circuit board. I unsoldered the largest ones and tested them off the board they still test good.

    I tested the 2N6488 and 2N6491 transistors 2 each in a TO-220 case. I could not get a good reading on the circuit board so I unsoldered them and they all test good.

    There are several parts I don't know what they are or how to test them. Some of the parts have several numbers I'm not sure which one is the part number. IFR244V 1()R524P there are 4 of these in a TO-220 case. MOSPEC F12C20A MA6E there are 2 of these in a TO-220 case. TIP41C CC04S MAR509 one of these in a TO-220 case.

    Now what?
     
    Last edited: Jan 14, 2012
  7. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    Did you look at basic car audio electronics web site? carry out voltage checks on the collector's of the o/p transistors.. do you have a scopeto aid tracing signal within the preamp. If the green led light's up ok move on to trace the audio signal. use a car battery charger/ 12v psu to power up the unit till it's running.
     
  8. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    there's on line information regarding these amp I just typed a quick search for bazooka amp's and lot's of them came up...try there bazooka web page for more info..
     
  9. 4pyros

    4pyros Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2010
    Messages:
    4,368
    Likes:
    282
    Location:
    Pennsylvania, USA
    Should be a IRF part number but its not 244. Can you look at it again?

    BTW what model amp is it?

    F12C20A is a double diode in the power supply circuit. The diodes are printed right on the case.

    TIP41C is a transistor.

    Don't use the last part of the numbers on the case they are manufacturing codes. just use the first part of the numbers and google them.
     
    Last edited: Jan 14, 2012
  10. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    The only test equipment I have is a VOM and an Amp Clamp. Sold my tube tester, signal generator, scope, many years ago.

    I have 2 soldering guns and an air compressor to unsolder circuit boards.
     
  11. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    I have 2 soldering guns and an air compressor to unsolder circuit boards.[/QUOTE]


    Soldering guns will overheat the pcb track's... you can make a tracer probe.. quick way would be get a phone lead chop an end off and solder a meter lead on the end plus the shielded part just hook a clip to use it as an earth return.. then use a small amp as a signal hearing aid. plug music signal in to the car amp and trace round the pre-amp circuit. such as from the volume pot onwards... did you look up bazooka site?
     
  12. 4pyros

    4pyros Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2010
    Messages:
    4,368
    Likes:
    282
    Location:
    Pennsylvania, USA
    gary; what model amp is it??
     
  13. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    I looked at the Bazooka site this amp is not listed.

    I have a pencil solder iron for circuit boards and 1 solder gun.

    I might experemente with this amp more today.
     
  14. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    Gray, can you turn the on it's front so we can see if there's any writing on it...thanks..
     
  15. 4pyros

    4pyros Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2010
    Messages:
    4,368
    Likes:
    282
    Location:
    Pennsylvania, USA
    gary; what model amp is it??
     
  16. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    ??? Are you wanting me to post a photo??? Not sure what your saying. Do you want me go see what writing is on the front???
     
  17. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    agree there we need the model number the solve this problem...
     
  18. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    yes just repost a picture of the front of the amp as your first picture just showed the inside...or if there's any writing on it to speed things up....
     
    Last edited: Jan 15, 2012
  19. Tann-44

    Tann-44 New Member

    Joined:
    Jan 12, 2012
    Messages:
    89
    Likes:
    1
    Location:
    Glasgow
    Just one thing did you try the tap it test? just like working on most circuit's back in the day..if a chassis was powered say, a amplifier with no sound we'red lightly tapped the circuit board to see if this had an effect on it.. anyway getting back to things does the power light stay on? because car amps work on lower in put signal level's use a cd/mp-3 player and slowly adjust volume to the i/p of the amp. in the passed i've noticed you can still hear the music even if the front amp gain is turned down!!
     
  20. gary350

    gary350 Well-Known Member

    Joined:
    Dec 28, 2005
    Messages:
    1,097
    Likes:
    53
    Location:
    Murfreesboro, TN 37129 USA
    Amp does not match photos on bazooka site. Look at photos and you will see why part number is the same.

    [​IMG]

    [​IMG]
     
    Last edited: Jan 15, 2012
  21. 4pyros

    4pyros Well-Known Member Most Helpful Member

    Joined:
    Oct 22, 2010
    Messages:
    4,368
    Likes:
    282
    Location:
    Pennsylvania, USA

Share This Page