Hifonics audio driver board

[seankane]

2 minutes all output fets remained cold.

 

[timwebb]

It's playing?

 

[seankane]

No its not playing, the amp is out of the sink, powered through a limiter, with a 4 ohm load hooked to the output terminals at idle.

This makes the DC go away but Perry wanted to know if anything got warm while the load was hooked up but all the fets stay cool.

I am wondering why I have the rail on the output terminals?

Wondering if Q4 and Q8 were defective if this could allow this condition.

 

[timwebb]

u have all the outputs in or just a few?

 

[seankane]

I have them all in, and I just figured it out. After the driver failure, I neglected to check the gate resistors again. They were all out of tolerance for the IRF9640's on one side by thousands of ohms and they took out all the fets with them.

I cant believe I did that, what a rookie move.

As Perry always says never "assume" anything.

I assumed they were still good and neglected to retest everything again after I repaired the driver board.

I dont have the 1/4 watt 10 ohm gate resistors in stock but I do have 1 watt flame proof 10 ohm resistors in stock. I dont think those will hurt anything for testing purposes do you?

What if I was just to leave them in permanentely?

 

[timwebb]

Ive used them in amps with sensitive boards so they dont burn. And they worked just fine.

 

[seankane]

Amp works awesome!!!

 

[timwebb]

nice!

 

[Perry Babin]

If you're going to sell it, use the correct parts. It looks better and is better for your reputation as a tech.

 

[seankane]

I have orderd them already, do you use metal film or carbon film not sure which is more reliable?

 

[Perry Babin]

Generally, metal film are available in 1% and 5% tolerance. Carbon film are generally 5%. If you need 1%, they'll almost certainly be metal film. If you only need 5%, you can use either. Neither is more reliable in real-world applications.

 

[bain86]

Does anyone know what goes into Q9 and Q11 on a HFI1500D board? these were pulled out of the amp before i gotten it.. both side have burnt resistors and I just want to make sure i order everything all in one shot so i am not waiting for 3 months. i am sorry if i am not in the right area of the forum.

 

[Perry Babin]

Please don't post in a repair thread that was started by someone else unless you are trying to offer assistance to the original poster.

Click on the red triangle in the lower left corner of your post and ask a moderator to move your post (and any replies to it) to a new thread (my post should be deleted).

After it's moved, I'll try to help you. Post a photo of the board with the missing transistors.