Digital design

[megael9]

Sorry Bobi.
I'm testing the driver board with an
Amp that uses the same driver board, but 16 MOSFET
per shoulder, the customer told me the model number is, DC audio 9k.
I`m trying to upload a picture, but I keep getting a failed error.
I`m sorry I did not mention the change in testing.
thanks again.

 

[Perry Babin]

The photo file size is likely too large. Crop it to cut out all but the relevant section of the photo and save at reduced quality (85% is a good compromise).

 

[megael9]

file size was reduced to 24 kb, and still getting, upload of file failed

 

[Perry Babin]

I tried uploading a file that I've uploaded several times before and it failed as well.

Connect the scope probe to the main ground (or the negative speaker terminal if it's connected to the secondary ground). Do you still see the 2k signal?

 

[megael9]

Using the speaker negative connector
There's No signal on any of the pads.

 

[Perry Babin]

That's what I'd expect.

Drive a strong 50-100Hz signal into the amp. Do you see a square wave of the same frequency and with an amplitude of approximately 10v (above the negative rail) on half of the gate pads for the output transistors?

 

[megael9]

Does the signal should be injected
into the RCA jacks?

 

[Perry Babin]

Yes.

 

[megael9]

What's the ground reference for the scope ?

 

[Perry Babin]

I'd try the main ground first. My scope is always grounded to the 12v power supply ground. I only VERY rarely need to use any other ground when using my scope.

 

[megael9]

I have no signal at all, but I'm not sure if my signal generator is working properly.
I haven't use it in a while.
I have the audio CDs with test tracks I bough from diyaudio site, can I inject that signal?

 

[Perry Babin]

You can confirm that the signal generator is working with your scope.

 

[megael9]

Signal looks ok without load, but as soon as I connect the RCA jack to the amp the signal gets distorted. even without powering up the amp. It looks like the generator Is not working ok under load.

 

[Perry Babin]

The load on the generator will be greater with the amp off.

If it's not working, use a test tone file (mp3, cd...).

 

[megael9]

Not knoing what to do. I pulled out my 50 khz fluke out of the closet,
just to rule out the scope. guess what the fluke scope works just fine,
I tried it at diffrent signals ranging from 50hz to 100 hz, and all fine.
16 of the 32 pads have a good square signal at 5.7 votls.
how can I test the other 16 pads to make sure they are OK before
I install the mosfets?

 

[Perry Babin]

It's not quite as easy. You need to supply voltage to the high-side of the driver ICs. I use a 9v battery. The negative terminal of the battery will go to the VS terminal of the IC. The positive terminal of the battery will go to the VB terminal of the IC.

If you are using the fluke scopemeter, you can measure the signal across pads 1 and 3 of the FETs. If you're using the other scope, you'll probably need to make a few other ground connections.

 

[megael9]

Looking at the PDF file typical circuit of ir21844 I see there is a diode between vcc and vb, the cathode is to the vb side and the anode to the vcc side, applying voltage to the
Vcc will provide voltage to both the vcc and vb, while applying voltage to vb will only apply voltage to vb, Is that what I'm support to do?

 

[megael9]

And one more question.
ones I check that the signal is present on all pads, Just for testing purpose, can I use only one MOSFET per bank? Another words 8 MOSFET, one per bank.

 

[Perry Babin]

The negative terminal of the battery will go to the VS terminal of the IC.

The positive terminal of the battery will go to the VB terminal of the IC.

 

[megael9]

Got it. Thanks
I will do the test tomorrow and let you know.
By the way thanks for helping me.
from the first time I joined the site, in 2009 you always been very helpful.
Thanks again.