Question about MTX Thunder 6500D Car Audio Amplifier
I blew my amp last week. (short circuit on the output speaker :S) I see that the four 75339P were smoke. I changed all four with IRF3205 and now the amp doesn't want to turn on. (no sound and led doesn't power on) Do you have an idea if I have something else blew? I have also test DC voltage on each of the 16 pins of the TL494 when power is on. Here's the DC voltage of the TL494 PIN #1 : 0 PIN #2 : 0 PIN #3 : 0.06v PIN #4 : 1.15v PIN #5 : 0 PIN #6 : 0 PIN #7 : 0 PIN #8 : 11.5v PIN #9 : 0 PIN #10 : 0 PIN #11 : 11.5v PIN #12 : 11.6v PIN #13 : 5v PIN #14 : 5v PIN #15 : 5v PIN #16 : 0 I don't what to do now. Thanks for your help! Dominique
SOURCE: my 7801 doesnt turn on
check pwm circuit amps turn on with 3-4 volts on mosfet gates ic 494, 5252or 555 controll these.hit me up for more
Posted on Aug 09, 2007
SOURCE: mtx81000d 3rd chance
The original output transistors (SSP45N20A - if I'm not mistaken) for this amplifier are very difficult to find and there are virtually no substitutes that will work without extensive modification. Many techs try to use the SSP45N20B but they don't work reliably.
If you do find replacements, expect to pay $15 or more each. It's possible that there are other problems also. For example, the over-current protection may not be working properly. When it's working properly, it will generally trip when the output transistors fail (which prevents damage to the subs).
This is an old design. The newer amps will be more reliable and will generally offer better protection for the speakers.
Posted on Nov 19, 2007
SOURCE: here it goes the amp powers on and seems ok
Sorry to say mate but that is one blown up amp! :(
My solution to this would be to get another amp
Sorry Matey
Upfront Audio
Posted on Apr 23, 2009
SOURCE: No sound from speakers, but there is power to amp
make sure the power wire and the remote wire have voltage. at least 12 volts. make sure the ground wire is good and has a good solid ground. after that make sure the rca cables are getting signal from the radio. if you have a small speaker or tweeter you can touch the wires from the speaker to the rca cables and it should play music very quietly. meter the subs and make sure theyre ok and not shorted or bad. if all that checks out good.... the amp is probably bad. start with all the simple stuff and work youre way up. if the amp has good power and signal and good speakers then the only thing thats left is the amp. good luck
Posted on Dec 30, 2009
SOURCE: My MTX JH600 works intermittently.
One of my friends had a amp like that , i looked at it an the inside of speaker box wires was touching , if thats not it then check ur power an ground , power wire must be the same size ground an if ur ground is not grounded good then u will get the cuting out .
Posted on Jun 11, 2011
Testimonial: "Great. Thanks"
Without a Sams Photofact or a service manual I would go directly to the Power IC which is the largest Integrated Circuit mounted to a large heat sink. If you see any fuses they are probably for the power supply since any fused circuit on the speaker output would be ineffective because the IC would be damaged before the fuse would blow, but you need to check them anyway. Since the short was at the speaker output your problem should be at the final stage of amplification, which is the Power Amp IC. Prior to the early 70's you would have transistors mounted to a heat sink which could be individually checked and replaced. Then manufactures started to use the Power Amp IC which are more costly but eliminate having to find matched pair transistors. All you can check on the Power Amp IC is if you have an input using an oscilloscope or signal tracer and the power to the IC. If you have an input signal and power to the device with no output, I would replace the IC. Unless you have a test circuit for the IC you cannot test it completely unless you have a device like a Huntron Tracker or build a test circuit using a signal generator and a power supply to measure the gain of the IC with an oscilloscope. Short of ordering a service manual this is a good place to start.
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