Sundown SAE-1000D

[Perry Babin]

What do you have on pin 1 of the TL072 and pin 7 of the LM211?

 

[Formas]

TL072 4.6v and LM211 4.8v ref to GND.

 

[Perry Babin]

Do you have positive and negative 5v on the supply pins of those IC?

 

[Formas]

yes those voltages are present, straight from off the sub regulators.

 

[Perry Babin]

Post the DC voltage on all terminals of the TL072.

 

[Formas]

DC voltages for TL072
pins
1. -4.8v
2. 0.0v
3. 0.0v
4. -4.9v
5. 0.6v
6. 0.6v
7. -4.8v
8. 5.0v

 

[Perry Babin]

pin 8 should have 5v.

 

[Formas]

yes, ive edited my post, its hard to get my probe on the actual pin as i have never sharpen my probes for the 10years ive been using it, think i will soon or by an insulated fine tip extender from fluke.

 

[Perry Babin]

Is the 10k resistor still connected between pins 1 and 2?

 

[Formas]

No its not, swing a leg to make the tests from post #21

 

[Perry Babin]

Reinstall the resistor and repost the numbers.

 

[Formas]

DC voltages for TL072 with 10k resistor across pins 1 and 2
Pins
1. 0.0v
2. -0.0v
3. 1.4v
4. -4.8v
5. 1.3v
6. 1.2v
7. -4.8
8. 5.0v

 

[Perry Babin]

Now, when you drive a signal into the amp, do you see a sine wave in pin 1 of the TL072 and a square wave swinging ±5v on pin 7 of the LM211?

 

[Formas]

Yes, those readings are present.

 

[Perry Babin]

Now check the signals at the gate pads for the output FETs.

 

[Formas]

Signal is there, the dc volts is also present (should that be or not), depending on which mosfet p-channel or n-channel gate pad, it swings positive or negative.

 

[Perry Babin]

Both drive signals have an amplitude of about 10v starting at the rail and going toward ground. The 9640s are driven from the positive rail. The 640s are driven from the negative rail.

 

[Formas]

I understand your explanation, but i just dont know whats causing the fets to be heated when inserted, so the voltage on the gate pad is ok?
what should my measurements be across the pads G to D, G to S, D to S and GND to all 3 pads respectively? (rail voltage is +/-60)

 

[Perry Babin]

Is the amplitude of the drive signal about 10v?

 

[Formas]

Yes, pretty much around that.