Rockford fosgate punch 45 no output

[Perry Babin]

That should be a solid trace there. Repair it and see if the voltage changes on pins 4 and 8 of those op-amps.

 

[chipper]

Perry! I made a bad, bad mistake on this! I repaired the trace and accidentally connected one of the speaker wires to mistaking it as the rem and fried
Something! Please help! I have a bunch of IRF3205's on hand and now the amp will not turn on! I'm really dumb!

 

[chipper]

Okay I'm not sure what went but the D40D8's are shorted which I assume are the drivers for the gets? And on both D44VH4's from gate to drain I get a reading of .530 ohms and drain to source I get a reading of .365 ohms are these no good?

 

[Perry Babin]

These are not FETs. They are BJTs. D44VH10s were typically used.

In place of the D40D8s (if they are shorted), you can use MPSA06s for testing.

Is the amp drawing excessive current?

 

[chipper]

WTF? So this is a BJT based power supply? Wow that's weird I thinking these were mosfets. I'm glad I know now I was about stick in IRF3205s ha ha.

Anyway a output burnt up so that's what made pop noise so I removed it and now the amp will turn on but the LED is very dim.

Also is the tab of the drivers for the power supply transistors connected to the middle leg of the transistor? D40D8? I removed the ps transistors and metered them and they tested fine but not sure on the drivers?

 

[chipper]

Oh yeah no excessive current draw.

 

[Perry Babin]

The tab of the driver is connected to the tab of the power supply transistor. The center legs are connected to the tabs for both transistors.

 

[chipper]

Hmm when I probed the center legs of the drivers I got a reading of .539 ohms and the other had no resistance I even probed the center legs to the center leg of the power supply transistor and got some resistance. I just want to find out why it's turns on but very dim. I have mpsa06 in TO-92 case will that one work?

 

[Perry Babin]

I was wrong. The center leg of the driver is the base. The 3rd leg is the collector which is connected to the tab.

The MPSA06 will work for testing.

 

[chipper]

Ohh so they are OK then? I got 'good' readings when I metered them. But what is making the amp turn on but with a very dim led?

 

[Perry Babin]

I don't know... yet.

Did you repair the trace and check the voltage on the op-amps again?

 

[chipper]

Right now I can't because it barely turns on... Yes I did fix the trace. I'll try switching ps driver tomorrow it's late.

 

[chipper]

I don't think it's anything with the drivers or the power supply transistors. I think something else fried and I can't find what's not allowing the amp to turn on. I've checked the ps transistors so many times and everything else in the power supply side. I need some help with this...

 

[Perry Babin]

Do the solder connections on the rectifier diodes look like they've overheated?

 

[chipper]

The ones near the transformer, right? If so no.

 

[Perry Babin]

Is the amp producing rail voltage?

Measure the DC voltage directly across the capacitors.

 

[chipper]

Orange / black wire side has 4.88 volts and the yelllow / brown side is not producing any voltage. Did I miss something?

 

[Perry Babin]

Remove all of the output transistors. Does it power up?