Orion HCCA 250G4 - Need Schematic

[seanengman]

I am new to repairing car amplifiers and my first project is an Orion HCCA 250G4.

I am looking for the schematic diagram and or pictures of the Bipolar Junction Transistors and the Field Effect Transistors. This amp was repaired once before I got it and I have reason to believe that they did not use the correct transistors.

Thank you,

Sean

 

[seanengman]

So I figured out the suspect transistors. For one, there are two toasted BJT's on one side of the circuit board (don't know all of the correct terminology, still learning). On the other side of the circuit board it appears as though the person who attempted to repair this amp before me replaced two of the NDP7060 FET's with NDP7050 which according to the specs have a Drain to Source of 50v versus the 60v of the NDP7060.

Now, what I am wondering is if I replace one FET or one BJT should I replace the entire line (correct term?)?

Thanks,

Sean

 

[Perry Babin]

In the power supply, there are two banks of parallel transistors (one for each primary winding). All in each bank must match.

The same thing goes for the output transistors. All parallel transistors must match. There are two groups of parallel transistors in each channel.

Of course, it will work without matching transistors but having parallel transistors matched relatively closely (matching date codes), will increase reliability.

 

[seanengman]

Thanks Perry. I thought I read that in your article somewhere, but couldn't find it in there.