Def Bonce AAB-7900.1D Output Mosfets, etc

[Tekjive]

Hey all, looking to know what these “H9” output FETs are on this DB AAB-7900.1D are, non-destructive high side right bank failure, looks to be a single MOSFET, took a cap out near the speaker inputs as well. Any info towards finding out what they are would be greatly appreciated, I’m thinking the IRF4115 but not certain. Also would be helpful to know what others are using for the signal/zener diodes at each FET bank as I’m not over familiar with this package type 😅

🖖🏼

 

[Perry Babin]

You need to realize that if you don't get a definitive answer to this and the driver ICs have on-board over-current protection, the over-current protection may not work well enough to protect the amplifier (they're already a bit sketchy). No one, as far as I know is recalculating and properly testing alternative output transistors.

The recommendations for output FETs that supposedly work generally doesn't mean anything more than that the FETs are generally suitable as replacements, unless they have been confirmed to survive when the output terminals are shorted AND the amplifier will play in it's lowest rated load without tripping the protection.

 

[Tekjive]

Ya I usually don’t take these in for this reason, but it’s a repeat client so I said I’d give it a shot. If possible I’d like to put FETs similar spec but tougher, just in case, but like you said it’ll need all kinds of testing, etc. we’ll see, I keep the post updated, just need a starting point first 😅

Hope all is well Perry

 

[Perry Babin]

Tougher generally means lower RDSon and that will prevent the over-current protection from engaging, possibly causing the supply to fail.

Again, this is if it uses ICs with on-board over-current protection.

Good call avoiding these. If no one would repair them due to the defaced components, people would buy something else.