USAudio model USA554X.

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redrooster

redrooster

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I can't find anything on this 660-watt D Class 12v car amplifier? I can't upload any photos because of a recent Microsoft update that has thrown a spanner into the works! It is red with a blue insert and has HM-ll Xtreme competition Amplifier written on it. Does anyone have a service manual and/or a schematic for it? I found it had 3 puffed out electro capacitors a cooked main diode and some fried MOSFETs and resistors so I replaced everything. I don't know where to get a 700-watt bulb for a dim bulb tester so I just connected a battery up with twin alligator clip wires to ground and B+ which both burnt off in a second. (There is no on/off switch) I'm new to D Class amps and I have no idea especially with no schematic? Can anyone help me with this at all?:D
 
redrooster

redrooster

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Perry Babin said:
For the 700 watt bulb... if you're referring to an inline current limiter, all you need is a 12v headlamp, for most amps. Most people use a 2 ohm, 100w tubular ceramic resistor and watch the amp meter in their 12v supply to know if there is a problem.
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I was wondering how that was done on these D Class amps? so thanks for that! I found a few photos I took of the amps insides on my computer before I took the amp apart. the bottom right-hand Mosfets have been replaced all except for one because it was still working? The original Mosfet blew immediately at turn on so it must've been on the verge of going! Oh well, I'll have to order another Mosfet.
 

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redrooster

redrooster

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Here are some photos, I'll send a photo of the solder side next. Three photos at a time don't work? I've removed 4 x RPF50N06 Mosfets from the top right-hand corner to test them.
 

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Perry Babin

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There is nothing class D there. It appears to be a 4 channel class B amplifier.

I don't have a diagram specifically for this amp (someone else may), what is the problem at this point and what questions do you have?

Close-up photos may be needed to answer specific questions about this amp.

Two of the gate resistors appear burned. Are they within tolerance?
 
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