infinity kappa

[Hexhclass]

20v/dv 5/us

 

[Hexhclass]

50v/dv 10/us

 

[Hexhclass]

50v/dv 5/us

 

[Hexhclass]

so the signal i get there is not a sign of oscillation?

 

[Perry Babin]

It's oscillating.

 

[Hexhclass]

If the signal on the drain had remain a straight line or flicker up and down on the scope that would indicate it is not oscillating ?

science the output is oscillating the problem might be audio signal is not reaching the sub channel?

 

[Perry Babin]

Yes. If you drive a signal into the sub channel, can you see a modulation on the output transistors?

Is the relay engaging?

 

[Hexhclass]

The relay not engaging
I get no voltage coming to its coil

 

[Perry Babin]

If you drive a signal into the sub channel, can you see a modulation on the output transistors?

 

[Hexhclass]

back on this amp.

I now have this amp producing audio on all channel but the four channels puts the amp in and out of protect about every minute .This only seem to happen if the crossover switches are set to HP and full.

I bypass one of the switch but no change. The amp will behave like that as soon as I apply audio signal. Currently all parts are in circuit. Any ideas?

 

[Perry Babin]

Monitor the DC on all channels to see if the DC starts to increase on one channel just before it goes into protect.

 

[Hexhclass]

The amp is cycling in and out of protect no matter what position the crossover switch is set.It just take longer to go in protect when it is on the Lp.The sub channel input is also causing the same results after the amp has been on for a while.

During the in and out of protect
DC on sub ch 0.303
Dc on 4ch was about 0.001 to 0.032


The voltage on pin 1 to 8 on the 494 IC does not change when the amp goes in protect. To test from pin 9 to 16,i will have to remove the driver board again which is
difficult on this amp

 

[Perry Babin]

Can you get the the pins with something like the probe in the photo? Dental pick with wire soldered to tip and heatshrink tubing over all but the end of the tip.

 

[Hexhclass]

The voltage on the other 8 pin does not change also. when amp is in protect rail voltage is still there.

1:3.709
2:5.01
3:0.035
4:0.024
5:1.579
6:3.756
7:0.002
8:12.18
9:4.23
10:4.23
11:12.18
12:12.16
13:5.01
14:5.01
15:2.784
16:1.791

 

[Perry Babin]

Is the voltage changing on one of the driver board pins when it goes into protect?

 

[Hexhclass]

Only the voltage on pin mark LED changes .

Relay disengage and red light comes on but rail voltage is still there. maybe this is not protect mode I am seeing .I pull Q4 but no change.

 

[Perry Babin]

Q4?

 

[Hexhclass]

Sorry its Q1

 

[Perry Babin]

Does the sub channel continue to produce clean audio on the output filter inductors (before the relay) when the relay disengages?

 

[Hexhclass]

I get no audio on the inductor when the relay disengage .