Sound Digital 8K

[mike49504]

Dont know if its normal in this amp But theese diodes read shorted when in the board:0.0006 but test fine when out of circuit

 

[luka]

where are they connected to?

 

[mike49504]

Cathode side connects to the IC's next to them and anode side connects to the cathode side of the diodes infront of the outputs, But i tested all outputs the test fine and i removed both ic's and they still test shorted in the board

 

[Perry Babin]

How much current is it drawing?

Did you confirm that you have a clean gate drive signal before replacing the power supply FETs?

Did you try removing the rectifiers?

Have you checked the outputs for leakage?

 

[Perry Babin]

The Stetsom didn't have pulldown resistors. If that's the case with this amp, pulling the ICs could cause the outputs to fail.

 

[mike49504]

I dont get any gate signals since the amp wont even power up.

I tested the outputs for leakage and they all test fine.

I removed the rectifiers and still the same thing they test shorted. (diodes)


Amp draws no current at all all i get is a blinking led.

I had the Outputs out of the amp when i pulled the IC's

 

[Perry Babin]

Contact the manufacturer to see if they have an owner's manual and/or a schematic diagram.

 

[mike49504]

Im gueessing the IC (2010) in the power supply is defective.

Im also gonna replace the transistors in the supply the legs arent looking the greatest and may break soon.


The drivers are KSP92 IS that that same as a MPSA92 ?

The other transistors are marked C33725 W 7d

Do you have a good part number for thoose?

Talked to them and he told me to send it to him for repair he wont give me any info on the amp

 

[Perry Babin]

Didn't you say that all of the FETs were defective?

Are the legs about to break on the new FETs?

Didn't you determine that the driver IC in the power supply was defective earlier?

 

[mike49504]

NO legs are fine on the new fets . The legs are ready to break on the small transistors.

I never replaced the IC as of yet. Guess i should have.


Im gonna put in a parts order right now Just need to know a couple things


The KSP92 transistor is that the same as MPSA92 ?

Also the diodes that read shorted say PH 1N 4148 so are thoose just the regular 1n4148's ?

 

[Perry Babin]

It appears that they are essentially the same.

Those should be 1N4148s.

With no power applied and the power supply driver IC out of the circuit, what's the resistance from pins 1 and 7 to ground?

 

[mike49504]

PIN1 to ground:0.997K

PIN7 to ground:13.28K

 

[Perry Babin]

Do they use pins 1 and 7 of the 2010 to drive the gates of the power supply FETs?

 

[mike49504]

YES PINS 1 and 7 connect to the gate resistors

 

[Perry Babin]

Are there two 1k pulldown resistors connected to each half of the gate drive circuits?

If so, is one out of tolerance (reading 13k instead of 1k)?

 

[mike49504]

Sorry i had PIN6 the first time

PINS 1 and 7 to ground both are:0.992K

 

[Perry Babin]

Pull the power supply driver IC. Does the red LED still give the same 13 flashes?

The amp shouldn't draw excessive current with the 2010 out of the circuit be be careful in case it does.

 

[mike49504]

YES it does

 

[Perry Babin]

Do you see any pulses on pads 10 or 12 for the 2010?

Have the probe on each point when remote is applied. There may be only a few pulses.

 

[mike49504]

Scope set to 10us .5volts/div. I see no pulses on pad 10 or 12 i tryed a few different times.