stetsom

[megael9]

Im working on a stetsom model # 5k2 e
this unit in going on protection mode, and
if I diconnect the 8 rectifier, protection
goes away. one of the 8 irfp90n20d was
leakage, and was replaced, I disconnected
all audio transistor {irfp90n20d} and power
up the amp, but no difference, no other transistor
was shortage or leakage, any idea on how to
troubleshoot this amp. thanks in advance.

 

[Perry Babin]

I'm somewhat familiar with the smaller version. Post a photo of the inside of the amp so I can see if it's similar to the smaller version.

 

[megael9]

Here are 3 pictures of this amp. by the way I was having
a fail err when try to up load this pictures, I then open this
picture with the paint program the comes with wndows,
save them, and that did the trick for me, hope this can help
others.

 

[Perry Babin]

That appears similar to the smaller one. In the smaller amp, you can pull the driver ICs and the amp will produce all drive signals to the inputs of the driver ICs. Pull the driver ICs in this one to see if you have a clean square wave on the inputs of the driver ICs.

 

[megael9]

just the 4 ics, not the 2 boards?

 

[Perry Babin]

Post a photo showing the tops of the ICs on the driver boards.

 

[megael9]

driver boards

please indicate the test points. thanks in advance.

 

[Perry Babin]

The IR ICs near the main board are the drivers. Leave the 4011s in their sockets.

 

[megael9]

driver boards

please indicate the test points. thanks in advance.

 

[Perry Babin]

Look up the datasheet for the driver ICs (resolution isn't good enough to read the numbers) and look at the signal on the Hin and Lin pins on the IC.

 

[megael9]

the pdf shows pin 10 and 11 to the be Hin and Lin pins.
know, do test without any signal at the rca jacks?

 

[Perry Babin]

You don't need an input signal.

 

[megael9]

I pulled the driver ics, and test the signal at the driver ics
imput, and no square wave, just a sine wive, on both ics.

 

[Perry Babin]

Are you sure that you have a good connection between the scope ground and the amp's ground?

Do you see a square wave on the gates of the power supply FETs?

 

[megael9]

No square wave on the power supply either,
but there is no valtage at the power supply rectifiers.
I notice there is valtage for just 1/2 second, at this
rectifiers. here are some pictures of the schematic.

 

[Perry Babin]

Does the protection or power LED flash a code?

 

[fcruz]

Make sure there is taroides leaking and if the pic is fed 5v if so see if 9 and 10 in the pic is square wave that goes to ir4427

 

[megael9]

5 sec protection 1 sec power.

 

[Perry Babin]

Does it draw excessive current from the 12v power supply as it tries to power up?

Are you sure that there are no shorted output transistors (or solder bridges between the legs of the output transistors)?

 

[megael9]

pic16f630 got vcc, but no signal on pin 9 and 10.