Audio Art 260.6XE

[caraudioguy2100]

Scope settings 10 us 5volts/div

2 0.1 if caps in series across gate and source here is what I get

 

[Perry Babin]

Does the PNP driver have its collector directly connected to ground?

Source, the 3rd leg?

 

[caraudioguy2100]

Yes the collector (middle leg) connects directly to ground

And yes 3rd leg of the fet source leg

 

[Perry Babin]

Is the signal the same on both banks?

Is the signal on the base of the two drivers a clean square wave like this was before loading?

 

[caraudioguy2100]

Yes both banks are the same .

And the waveform on the drivers is good like before loading it.

 

[caraudioguy2100]

Replaced the chipset (494) and replaced the drivers again .

The drive is good all the way down to the gate resistor with it loaded then at the gate resistor the drive gets goofy like in the previous posts .

 

[caraudioguy2100]

Here is what I get if I load it with a fet instead of caps .
Scope settings 10us 5 volts /div

 

[Perry Babin]

That's bad. What value are the pulldown resistors between the base of the drivers and the collector of the PNP driver (ground)?

If it's open, install something between a 1k and a 330 ohm on each driver pair to see if it helps.

 

[caraudioguy2100]

Would the 2n4401 and 4403 work in the power supply as drivers replacing the c945 and A733 ?

The drivers I put it tested good but we’re used so wondering if I might have a bad driver somewhere

 

[Perry Babin]

The drivers are likely OK. What are the pulldown resistor values?

 

[caraudioguy2100]

There are 56 ohm resistors connected to the drains and 470 ohm resistors connected to the source legs

 

[Perry Babin]

With no power applied, measure the resistance between pin 9/10 and pin 7 of the 494. What do you read on those two?

 

[caraudioguy2100]

Resistance from pin 9 to pin 10:0.946k

Resistance from pin 9 to pin 7:0.474k

Resistance from pin 10 to pin 7:0.471k

 

[Perry Babin]

Do you see a 470 ohm resistor connected across the points that are reading 470 ohms?

 

[caraudioguy2100]

Yes

 

[Perry Babin]

What does the drive signal look like on pins 9/10 of the 494?

 

[caraudioguy2100]

Scope is 10us 5 volts/div

Here is what I get on pins 9/10 they look the same

 

[Perry Babin]

If you see the same signal at the base of the drivers, the drivers are bad.

 

[caraudioguy2100]

Would the 2n4401/4403 work to replace the originals C945 and A733?

 

[Perry Babin]

You can use virtually anything. The PS drivers are not really critical. The 4401/4403 will be OK.

The pin configuration is different so you'll have to twist the base and emitter leads.