Rockford Fosgate Punch 800.2

[seankane]

Post #19 one side of the p/s fets has a square wave on the gates and nothing on the drain but the other side looks like its trying to produce a square wave on the drain but very small deflection almost hardly noticeable.

 

[Perry Babin]

How can the outputs be getting hot if the power supply isn't producing rail voltage (can't produce rail voltage without oscillation on the drains)?

 

[seankane]

The power supply seems to be producing rail voltage there is 60vdc on 1 leg of each rectifier but each time the amp pulses the meter reads OL even set on DC volts.

 

[seankane]

I removed the 5 IRF640 outputs from the other channel and the pulsing has stopped the amp idles fine. Wierd they didnt test shorted in the circuit.

I am wondering if I put new outputs in their place if the pulsing will come back?

 

[Perry Babin]

It could be pulsing when the amp tries to enable the outputs.

I'm working from the 2380 board schematic so I'm not sure it matches yours. C5 is the delay cap. Short it's positive and negative terminals with a jumper wire. Does the power supply come up and produce both positive and negative rail voltage?

 

[seankane]

3083 board here read my last post.

 

[Perry Babin]

I don't think the outputs are the problem. That's why I suggested what I did.

 

[seankane]

OK understood I will replace the outputs and try as you suggested.

 

[seankane]

OK I replaced the defective channels outputs with same result the pulsing, when I ran the jumper wire between +/- terminals of C5 the amp idles fine.

Thoughts?

 

[seankane]

With +/- terminals of C5 shorted in powers up and idles fine and produces +/- rail voltage.

 

[Perry Babin]

Is there any DC on the output of that channel?

If not, short the bias transistor from collector to emitter with a jumper wire and remove the jumper from C5. Does the amp power up and idle?

 

[seankane]

All the outputs are in the amp now.

The channel I originally posted the picture of with all the burned source resistors has no DC.

The channel I replaced the 6 IRF640's in has 0.220 vdc.

Shall I do the jumper on Q308 still?

 

[seankane]

Is there any DC on the output of that channel?

If not, short the bias transistor from collector to emitter with a jumper wire and remove the jumper from C5. Does the amp power up and idle?

There is a small amount of DC on that channel about 0.220 vdc, but I soldered a jumper from collector to emitter on Q308 and removed the jumper from C5 and the amp pulses.

0 amps to 40 amps over and over.

 

[Perry Babin]

Remove all jumpers and lift Qx06 and Qx07 (I'm not sure which channel this is). Does the amp still pulse?

Do you have any DC across the speaker terminals with those transistors out of the circuit?

 

[seankane]

I will lift Qx06 and Qx07 in both channels. Even when the IRF640's were removed as soon as I put the outputs back in the defective channel you saw the picture of it started pulsing.

Seems to only pulse when the IRF640's of either channel are installed.

 

[seankane]

I removed Q306 and Q307 first then powered the amp still pulsing.

Left Q306 and Q307 out of the circuit and removed Q206 and Q207 and the amp stopped pulsing and idles fine with no DC on either terminal.

Thoughts?

 

[Perry Babin]

Which channel has the heating outputs (200 series or 300 series)?

 

[seankane]

3 series

 

[Perry Babin]

Does the 300 series channel now produce clean audio?

 

[seankane]

Scope settings are 2ms 2v/d and no neither channel does.

When the volume is first increased it looks ok go a little higher it looks like a shark fin, starts curving back to a point.