Kicker IX1302

[m4ick]

This amp had 40ohms across + and - power terminals. I bank of power supply fets was close to 0 ohms.

With no power supply fets and no power supply drivers installed I get no output from the 494.

Here is what I get DCV referenced to - power terminal:
01: 0v
02: 4.89v
03: 4.74v
04: Starts at about 5v and quickly drops to 0v
05: 1.41v - has sawtooth.
06: 3.54v
07: 0v
08: 14v
09: 0v
10: 0v
11: 14v
12: 14v
13: 4.88v
14: 4.88v
15: 4.88v
16: 5.02v

Pin 3 is being driven high even though pin 1 is lower than pin 2. Could this be a bad 494?

 

[brandes.cm]

Why is 16 high, something is setting it to 5V?

 

[Perry Babin]

Try reducing the 12v supply voltage to about 13v.

 

[m4ick]

Can't manually adjust my power supply so I put some 270ohm resistors in parallel and I get signal. Is this thing just that heavily regulated? Why does that cause the drive signal to appear?

Should I expect that when I install PS fets and drivers that it will still be there?

EDIT: That is, the resistors are in parallel with each other, inline with B+. It's all I can do to limit the voltage.

 

[Perry Babin]

What is the voltage across the B+ and ground terminals of the amp with and without the resistors in series?

What make/model 12v power supply do you have?

 

[m4ick]

Wow, this thing is putting out close to 16v with nothing connected. Seems high.

Is this amp sensitive to over voltage?

Maybe it's time to break out an old computer PSU.

 

[Perry Babin]

It may be adjustable internally.

Some amps have over-voltage protection. This one likely does and 16v was just a bit too high.

 

[m4ick]

Ok, I hooked the amp to a computer power supply and I get 12.03V across B+ and -. I'm still in protect. With resistors in the B+ line it reduces to just over 5v and powers on.

 

[Perry Babin]

What's the DC voltage on pins 15 and 16 at 12v in?

 

[m4ick]

This is what I get now:
01: 0v
02: 5v
03: 0.07v
04: 2.69v
05: 0v
06: 3.74v
07: 0v
08: 12v
09: .03v
10: .05v
11: 12v
12: 12v
13: 5v
14: 5v
15: 5v
16: 3.86v

 

[m4ick]

Sorry Perry, I got ahead of myself and installed the 2 power supply fets before testing on 12V. With them removed it powers on and I get drive signal.

 

[m4ick]

I don't have any shorted outputs, not sure why it is in protect.

 

[m4ick]

With rectifiers removed it remains in protect. After removing the jumpers going to the voltage regulation rectifier diodes it powers up.

Both zeners appear ok, both shunt resistors appear ok, no shorted caps or diodes but the whole area is very toasty (not burned, just brown). I'm a little concerned that broken solder joints may have occurred in that area. I have touched up all solder joints on the voltage regs. How can I tell if the op-amps are bad? I get the feeling a zener had a bad solder joint. Maybe killed my op amps.

 

[m4ick]

I see in your tutorial how to connect + to vcc+ via 2 ohm resistor and connect - to vcc-. Is that my best bet to find bad op amps?

 

[Perry Babin]

Connecting the op-amps to the 12v supply via the 2 ohm resistor is only to find shorted or leaky op-amps.

Reinstall the jumpers to the regulators. With the rectifiers out, are the voltages on the 494 the same as the last ones you posted?

 

[m4ick]

I may have made a mistake on pin 5 last time, this is what I have with voltage regs connected and the main rectifiers removed:

01: 0v
02: 5v
03: 0.07v
04: 2.69v
05: 1.53v
06: 3.74v
07: 0v
08: 12v
09: .04v
10: .05v
11: 12v
12: 12v
13: 5v
14: 5v
15: 5v
16: 3.86v

 

[Perry Babin]

Looking at pins 9 and 10 on the scope (5v/div, 10us), do you see any pulses?

 

[m4ick]

Does not pulse like an output inductor with a shorted output. Pin 9 shows a very tiny spike but just 0v otherwise, pin 10 has a slightly larger spike but 0v otherwise.

It still seems odd, though, that disconnecting the voltage regs brings it out of protect.

 

[Perry Babin]

The protection LED on some of the IX series amps was driven (in a round about way) by the pulses on the drive for the FETs. It didn't necessarily mean that the amp had a fault.

Do you see a transistor near pin 4 of the 494 that has its collector connected to pin 4?

 

[m4ick]

Yes, Q704 is a KTA1266-GR.

The protect LED is a 3 lead LED for both power (green) and protect (red).