Rockford Fosgate Power 360a2

[Perry Babin]

I didn't catch it the first time but the A56 is a PNP transistors. The 3904 is an NPN transistor and the correct part for Q222.

 

[seankane]

So you are saying?

 

[Perry Babin]

Something changed between the time you installed the A56 and the time you removed it. Maybe you cleared the fault. Try reinstalling the three transistors and R274 to see if the DC returns.

 

[seankane]

Everything is re-installed except the A56 and there is no DC on the terminal. Do you want me to reinstall the A56 and see if it comes back?

 

[seankane]

One question... what is the purpose of D206? I THINK it may have a missing trace. Upon inspecting closely with a magnifying glass it looks like a trace is missing to a resistor maybe>

 

[seankane]

D206 should be traced to which two components?

 

[seankane]

After cleaning the flux D206 traces are fine, sorry for the false alarm.

I measured the DC current on the A56 pads with it removed and power applied and here is what I found........

The emitter pad 0.000 vdc

The base pad ~8.67 vdc

The collector pad ~36.42 vdc

 

[seankane]

The collector pad goes to D204 and D207 and from there all over.
I reinstalled the NEW A56 and same result ~21.76 vdc on bridging terminal. Still wondering why the dc goes away when the A56 is out of circuit??? Maybe I am not on to anything but I thought I was.

 

[Perry Babin]

I didn't realize that Q213 was an A56.

I thought that that transistor had been removed and that the DC was still present earlier.

 

[seankane]

So does this open up more trouble shooting possibilities or are we back to not being able to go any further on this one?

 

[Perry Babin]

At one time, I thought that Q213, Q222, D204 and R274 were out of the circuit and there was still DC. If that's the case, I don't know what more we can do. Do you want to send me the board?

 

[seankane]

I could send it with the 100ix's I will e-mail you tomorrow, or later today I should say. I put everything back in the circuit, except the A56 and there is no DC. As soon as I put the A56 back in there is dc. I dont think we ever removed Q213 from the circuit in our troubleshooting. I just did it for the heck of it and the DC went away. Not sure what to think on it.

 

[seankane]

Ok Perry I know where I went wrong and I feel really bad. This is a big goof up on my part. The numbers are really hard to read on this board for some reason, like they were double printed. When you were asking me about Q213 this whole time I was lifting Q218. Thats why it was so confusing. The reason I found out is because I had another punch 360a2 laying around and opened it to look at the numbers on the board. So in our first few pages when you asked me to lift Q213 I lifted Q218. So yes as soon as Q213 was lifted (A56) the DC went away. I dont know if we can start from that point again, I would like to get this fixed.

 

[djmaxspl]

360a2

I have a question? Whats kind power can these put out? Is it more than 450 watts bridged?

I used to sell these amps. The model number denotes total power(360) and number of channels (a2) at a 4 ohm stereo load. The amp does more power at 4 ohm mono; anywhere from 450-550 watts at 4 ohm mono depending on voltage

 

[Perry Babin]

Ok but not until Monday some time.

 

[seankane]

No problem, thanks again.

 

[seankane]

Hey Perry not sure when or where you want to start on this one, I guess I will leave that up to you. If you want to do one at a time I totally understand.

 

[seankane]

Ok here we go again..............

All pots and switches are fully functional moving them full range of motion.

Have good supply and remote voltage inside amp.

All op-amps have -13.40 vdc on pin 4 and +14.40 vdc on pin 8.

Rail voltage is 74 vdc, blk prb center leg of CR1 rd prb center leg of CR2

I have -21.00 vdc on R- bridging terminal.

I have 0.405 vdc on gate leg of P/S FETS.

LM339 reads as follows:

pin1: 4.96 vdc
pin2: 4.96 vdc
pin3: 14.55 vdc
pin4: 0.001 vdc
pin5: 1.998 vdc
pin6: 4.39 vdc
pin7: 4.94 vdc
pin8: 4.94 vdc
pin9: 5.35 vdc
pin10: 4.94 vdc
pin11: 8.25 vdc
pin12: 0.001 vdc
pin13: 4.96 vdc
pin14: 15.18 vdc

The TL494C reads as follows:

pin1: 2.320 vdc
pin2: 2.316 vdc
pin3: 0.023 vdc
pin4: 0.024 vdc
pin5: 0.025 vdc
pin6: 0.025 vdc
pin7: 0.027 vdc
pin8: 14.55 vdc
pin9: 0.315 vdc
pin10: 0.316 vdc
pin11: 0.020 vdc
pin12: 0.020 vdc
pin13: 0.019 vdc
pin14: 0.019 vdc
pin15: 0.019 vdc
pin16: o.001 vdc

Q225 gate to source voltage: 2.745 vdc
Q218 gate to source voltage: 2.745 vdc
Q219 gate to source voltage: -0.030 vdc
Q224 gate to source voltage: -0.026 vdc

Q225 drain voltage: -21.66 vdc
Q218 drain voltage: -21.66 vdc
Q219 drain voltage: -21.66 vdc
Q224 drain voltage: -21.66 vdc

This should be a good start, why am I getting the negative voltage on the bridging terminal?

 

[Perry Babin]

I think you lost one of the probe connections on the 494 but it's not important here since it's producing rail voltage.

Lift Q209 and Q211. Does that eliminate the DC?

 

[seankane]

I think you lost one of the probe connections on the 494 but it's not important here since it's producing rail voltage.

Lift Q209 and Q211. Does that eliminate the DC?

Not totally but it does drop down to -1.556 vdc from -21.00 vdc

Thats quite a bit.........thoughts??