Sound Digital 8K

[mike49504]

All of the fets were defective in this amp (IRF1404) . I removed them and between pads 1 and 3 i have 15 ohms.

I believe the driver is a IR2010 Ic.

With the ic in the amp pads 1 and 3 connect to pin7.

From pad 1 to pin7 i get 10 ohms

From pad 3 to pin7 i get 5 ohms.

Is this normal or is the IC likely defective?

[harvie256]

Do you have an oscilloscope? With the power MOSFET's removed, you can apply power and look at the gate drive signal. I don't know this amp, but all the one's I've played with and built use a separate control IC (e.g. a TL494), and you should be able to probe the outputs of that if you're not getting anything from the mosfet driver. I wouldn't bother trying to look at resistance of the IC's unless that's all you have to measure with.

Are you sure it's in IR2010? These are a High & Low side mosfet driver, it would be unusual for a high side driver to be employed in a car amp, as the voltages are too low to make a full bridge configuration any use, in fact it would be quite a pain. Normally they are all push-pull configs that use just dual low side drivers.

As for your stuffed mosfets. Just be aware that blown power mosfets in a switchmode power supply is a given when almost anything goes wrong. It really is very little help in narrowing down what the cause of the problem is. So be sure to look thoroughly at the output side of the transformer and what else could potentially have gone wrong i.e. overloaded the supply.

[Perry Babin]

The 1404s are typically used in the power supply. The 2010 is typically used for the audio section. Are you sure that they're using the 2010 for the power supply?

[mike49504]

Heres a pic of the board. Next to the 28 pin IC is a 2010.

On the other side of the amp there are 2 2010's

[Perry Babin]

This is similar to the Stetsom amps. The PIC is used to do everything but it doesn't have the ability to drive the FETs. They use a different driver in the Stetsom amps. They're likely only using the low side drivers in this IC since it appears that all of the sources of the FETs are grounded.

Pull the driver IC and measure the resistance again.

[mike49504]

Between pads 1-3:1.004K

From Pad1 to Pin7:10.1 ohms

From pad3 to Pin7:0.994K

[harvie256]

Yep your quite right it is, and that's a PIC next to it. This is honestly a bit difficult to see what's going on just from this pic. If you just follow the gates (pin 1) of the mosfets back, you should arrive at some sort of driver.

[Perry Babin]

If they're using 10 ohm gate resistors, that seems OK.

Do any of the gates read 10 ohms to pin 1?

[mike49504]

So i have to order a new 2010 IC

Pin 8 of the PIC connects to pad 3 for the fets.

Should i replace the PIC also?

[Perry Babin]

You can't replace the PIC. It has to be programmed and will work for only one amp (or for a group of very similar amps). If the PIC has failed and the manufacturer won't supply it, there's no way to repair it (unless you take one from another amp).