Rockford Fosgate Punch 600a4

[objext]

Could be my imagination, but I feel like the power LED was also brighter when I had pins 2, 13, & 14 lifted, if that means anything to you.

 

[Perry Babin]

Recheck the voltages that you posted for the LM339. Are they still the same?

 

[objext]

I had to pack it up for the night. I'll check again tomorrow or Saturday. Thanks for bearing with me.

 

[objext]

Ok, with B+ & remote connected, the new LM339 reads...

Pin 1: -0.612
Pin 2: 3.10 fluctuating slightly
Pin 3: 12.7
Pin 4: 0.314
Pin 5: 2.493
Pin 6: 4.962
Pin 7: 3.556
Pin 8: 4.202
Pin 9: 4.962
Pin 10: 4.962
Pin 11: 7.93
Pin 12: 0
Pin 13: 3.10 fluctuating slightly
Pin 14: 3.10 fluctuating slightly

 

[Perry Babin]

The 339 is an open collector device that can only pull down. When a non-inverting input is higher than the inverting input, the output for that section switches off.

All 3 of the protection circuit sections should be off and not able to stop pin 7 from charging.

When, all you did was to lift the protection comparator outputs, pin 7 charged.

Something else seems to be happening but with the information I see here, I don't know what it could be.

 

[objext]

I have a 2nd 600a4 (the one with the very hot running regulators, but otherwise working). Is there anything I could compare with a multimeter or ESR meter that you might suspect would cause this one to not power up correctly?

 

[objext]

Here's a comparison of the non-powering vs the powering 339 voltages with only remote, and with full power.

Non-powering:

0.008	-0.607
5.85	3.1
12.67	12.69
0.347	0.349
2.56	2.493
4.961	4.962
6.224	3.562
4.201	4.2
4.961	4.962
4.961	4.962
7.93	7.93
0	0.001
5.85	3.1
5.85	3.1

Powering:

0.008	14.23
5.84	5.92
12.66	13.54
0.284	0.326
2.518	2.52
4.907	4.906
6.263	6.32
4.195	4.119
4.906	4.906
4.906	4.906
7.92	7.77
0	0.001
5.84	5.92
5.84	5.92

 

[Perry Babin]

Compare the voltage on the LM339.

 

[Perry Babin]

What do you mean by 'powering' and 'non-powering'?

 

[objext]

The first table of voltages is from the 339 on the amp in question that won't fully power up (non-powering), with B- & remote only values on the left, and B-, B+, and remote on the right.

The second table is of my other 600a4 that does power up (powering). Sorry if that was a stupid set of terms.

I'm also getting much different readings across Q10 & Q11 between the two amps.

 

[objext]

Q10/Q11 compare the same from one amp to the other in diode mode, but have fairly different resistances from one amp to the other.

 

[Perry Babin]

Lift Q9. The amp won't turn off with the remote with that transistor out of the circuit but let's see if the amp works without it.

Is pin 5 a clean sawtooth waveform?

What's its amplitude (scope)?

 

[objext]

Removed Q9. Amp powers to 0.30A draw and 339 voltages are:

Pin1: -0.903
Pin2: -0.684
Pin3: 12.61
Pin4: 0.129
Pin5: 2.255
Pin6: 4.961
Pin7: -0.27
Pin8: 4.151
Pin9: 4.961
Pin10: 4.961
Pin11: 7.84
Pin12: -0.001
Pin13: -0.684
Pin14: -0.684

 

[objext]

And I still don't have a scope :|

 

[Perry Babin]

Is there any contamination on the board?

If you place the black probe on ground and rub the red probe on the board around the 494 and 339, does the meter ever see any DC voltage?

 

[objext]

I don't see any contamination. The board is very clean. Not brand new, but as good as I see them. I don't seem to pick up any stray voltage, no.

 

[objext]

Here are a couple pictures. Just some flux now from reworking the parts I lifted/replaced.

 

[Perry Babin]

I don't know where the negative voltage is coming from.

What is the voltage on the gates of the PS FETs?

 

[objext]

With only B- & remote I have

5.202v at Q5/Q7/Q12
5.194v at Q6/Q8/Q13

With B-, B+, & remote I have

0.236v at Q5/Q7/Q12
0.423v at Q6/Q8/Q13

These are similar values to what I had initially with nothing changed/lifted.

 

[objext]

Negative voltage seems to be coming from/across R370(?) which is connected to R37 in the power supply