Team Cactus 7kw

[mike49504]

I got this amp in for repair and it had blown outputs and driver ic's I put new outputs in the amp Output driver board is still out of the amp.

Amp is stuck in protection mode Heres the voltages i have.

LM293
1:0.16
2:13.86
3:5.05
4:0.00
5:1.38
6:3.97
7:0.17
8:13.87

TL494
1:0.06
2:5.05
3:4.90
4:5.02
5:1.49
6:3.73
7:0.00
8:13.86
9:0.00
10:0.00
11:13.86
12:13.86
13:5.05
14:5.05
15:5.05
16:6.58

 

[Perry Babin]

Pin 16 is shutting it down.

 

[mike49504]

There are 2 transistors near the 494 an A1266 and a C3198 This is what i have for voltgaes on thoose

A1266
1:13.86
2:13.39
3:13.56

C3198

1:0
2:0
3:0.68

 

[Perry Babin]

Is pin 2 of the 1266 connected to pin 16?

 

[mike49504]

A1266 middle pin goes to a diode then goes to a 100K resistor then the resistor is directly connected to pin 16

On the diode that connects to the middle pin of the 1266 has 13.28 volts on both sides of it then the resistor has 13.28 volts on 1 side and 6.60 volts on the other that connects to pin 16

 

[Perry Babin]

Removing the 1266 may defeat the protection circuit but you'll have to be careful because it may draw excessive current.

 

[mike49504]

With the A1266 removed amp powers up .

With a current limiter in line amp idles about 3-4 amps without it amp idles around 13 amps

 

[Perry Babin]

Is anything getting hot?

 

[mike49504]

I only let it idle for about 10 secs without a limiter and none of the fets got hot .

 

[mike49504]

Dont know if its normal but i tested for output and my 1 ohm 25 watt current limiter is smoking .


When testing the output amp has output but very distorted

 

[Perry Babin]

It's normal for the resistor to get hot.

Is the square wave on all of the outputs swinging cleanly from rail to rail?

 

[mike49504]

Is the square wave suppose to be there for a sec then nothing then there for a second then nothing and it just keeps doing that

 

[Perry Babin]

No. It should be constant. Is the voltage on the center leg of the D1302 pulsing?

 

[mike49504]

There are 2 D1302's in this amp both of them the center legs voltage is pulsing

 

[Perry Babin]

If there's an LM293 near the 494, is pin 1 or 7 pulsing?

 

[mike49504]

NO. But the A1266 is still removed controlling pin 16 on the 494

 

[Perry Babin]

Can you post a photo (or 2 or 3) of the amp?

 

[mike49504]

Heres some pics of the amp if you need pics of a certain part let me know

 

[Perry Babin]

What's the op-amp/comparator near the 494?

Are pins 1 or 7 pulsing on it?

 

[mike49504]

The op-amp is a LM293 pins 1 and pin 7 stay constant at 0.01 volts