infinity kappa

[Hexhclass]

This amp is in protect. I pull the center leg on the rectifier no change.
Did not find any shorted component.

#494

1:3.757
2:5.01
3:0.032
4:6.32
5:1.640
6:3.717
7:0.000
8:12.38
9:0.00
10:0.00
11:12.38
12:12.34
13:5.01
14:5.01
15:2.824
16:1.789

 

[ultra]

You need to see what is driving pin 4 hi

 

[Hexhclass]

pin 4 is connected to a transistor through a 15k resistor.when i pull the transistor amp
produce rail voltage.

SMD Q1 with M6 on it.not sure what type of transistor it is yet.

1:11.62
2;12.66
3:12.33

out of circuit pads read
1:7.20
2:0.034
3:12.17

 

[Hexhclass]

driver board

 

[Perry Babin]

Is Kappa the entire model number?

 

[Hexhclass]

infinity kappa five

 

[Hexhclass]

For Q1 pin numbers wrong


in circuit

1:12.32
2:11.62
3:12.62

out of circuit ,voltage on pads

1:12.17
2:7.20
3:0.039

 

[Perry Babin]

Is the transistor leaky or shorted?

That transistor is used in the protection circuit. If it's not defective, one of the channels is driving the amp into protection. Do all channels produce clean audio with that transistor out of the circuit?

 

[Hexhclass]

transistor tested ok out of circuit.

The front and rear channels play good audio but the sub channel
has no audio.

 

[Perry Babin]

Do you have rail voltage on the sub channel?

If so, do you have rail-rail oscillation on the output transistors?

 

[Hexhclass]

I see only four output FETs and they all have rail voltage.
Not sure how it is a five channel.

How do i measure rail to rail oscillation?

 

[Perry Babin]

The output transistors for 4 channels look like the ones in the following image.

The drain (tab) of Q103E should have rail-rail oscillation. You can see it on a scope.

 

[Hexhclass]

found them, these transistor look like a naked diy. The 4 channels are working so I guess i will not be touching them.

I will check for oscillation and post wave form tomorrow .

 

[Hexhclass]

All I get on the drain was tiny triangle wave form. I tried different setting expecting a better wave from but none.

Scope was grounded to main ground, I also tried RCA ground
10v/dv 10/us

 

[Perry Babin]

Sometimes you have to drive an audio signal into the amp to force it to oscillate. Did you try checking for R-R oscillation with audio?

 

[Hexhclass]

I did not try it with audio. I will repeat the test with audio.

 

[Hexhclass]

With audio

scope reference line set one major division from the top
10v/dv 1/us

 

[Perry Babin]

Why didn't you center the trace on the display?

That looks like 600kHz+. That's too high. Are you sure you have the scope set to 1us? If at 10us, it would be more reasonable.

What point in the circuit were you probing for this waveform?

 

[Hexhclass]

i did not center it because i could not seed the bottom of wave form.
scope was set to 1us for above photo.

The drain of Q103E is the test point.

using main ground



10v/dv 10/us first pic

10v/dv 5/us second pic

 

[Perry Babin]

Why not set the scope to 20 or 50v?