Alpine pdx-1.1000

[rhempz01]

I have alpine that has no signs of life at all. The power supply is a bit different than I am used to. I believe these small silver components to be transistors but unsure. I removed the shorted components still nothing not even a short curcuit?

 

[rhempz01]

Ps top

 

[rhempz01]

Ps bottom

 

[Perry Babin]

Are you referring to the FETs in the attached photo marked IR6612?

 

[rhempz01]

Yes perry. There is four banks of these transistors on the bottom of the board.

 

[Perry Babin]

Yes. Those are the PS FETs. The attached photo shows the bottom of the FET. It's on the face of a TO-220 transistor for scale. If you don't find any shorted, don't do anything to them. They can be difficult to replace.

This supply is a full bridge design, not a standard push-pull design.

 

[rhempz01]

I know that one of the output driver ic is blown and four fets are shorted, I also removed a diode it was shorted,none of them are reading shorted perry. Typo error. They all show fine, so I need to figure out why I have no power at all. The no power at all issue.

 

[rhempz01]

The irli3803 transistor is reading shorted gate to source.

 

[Perry Babin]

That's normal for that transistor in this circuit.

 

[Perry Babin]

Check the tiny little gate resistors for the outputs.

 

[Perry Babin]

Sorry for the multiple posts. The RCA board has to be plugged in for the amp to power up.

 

[rhempz01]

All good 11.10hms.

 

[Perry Babin]

Are the 6.8 ohm groups OK? R404 and R414 groups.

 

[rhempz01]

That's ok, I thought that as well. So even with plugged in and one 10amp fuse nothing. The 6R8; are all within tolerence as well. If I probe the positive and negitive post terminal I get open to short over and over.

 

[Perry Babin]

Did all 4 outputs in one channel short? You generally see only 2 fail.

Do you have a replacement driver IC?

 

[rhempz01]

Only two. No I do not I put the order in yesterday. And I need a part number for the diode SI20

 

[Perry Babin]

email me
babin_perry@yahoo.com

 

[rhempz01]

So the ribbon cable was damaged that's why it wouldn't power up at all. So I'm going to get some parts ordered for this. Thanks perry.

 

[rhempz01]

Ok so perry I installed the new driver ic and four new irfb4227 in the bank. Installed the new diode. The same happens the, on then off.

 

[Perry Babin]

Do you see rail-rail oscillation on all of the outputs (even intermittently)?