Rockford Punch 800a2

[seankane]

Hello Perry while I am replacing the output fets on the bd15001 I thought I would pic your brain on the punch 800a2. It powers up fine does not draw excess current but has no output. Not so much as a sound or anything. Any thoughts on where to start?? The board number is PC-2038-C I dont think the output fets are faulty maybe check some op-amp voltages??

 

[Perry Babin]

Post the DC voltage on all of the pins of the LM339.

IC#
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:

 

[seankane]

Post the DC voltage on all of the pins of the LM339.

IC#
Pin 1: 20.46 vdc
Pin 2: 5.07 vdc
Pin 3: 19.78 vdc
Pin 4: .164 vdc
Pin 5: 2.412 vdc
Pin 6: 4.92 vdc
Pin 7: 5.46 vdc
Pin 8: 4.35 vdc
Pin 9: 4.92 vdc
Pin 10: 4.92 vdc
Pin 11: 8.24 vdc
Pin 12: .001 vdc
Pin 13: 5.07 vdc
Pin 14: 5.07 vdc

 

[Perry Babin]

What's the voltage across R206 and R306?

Have you checked for audio on the output pins of the op-amps?

 

[seankane]

What's the voltage across R206 and R306?

Have you checked for audio on the output pins of the op-amps?

I cannot locate R206 and R306?

I have not checked the op-amp pins for audio would that be pin 8 on all of them?

 

[Perry Babin]

See attached.

Look for signal on pins 1 and 7. Also confirm that they all have the ±15 on the power supply pins.

 

[seankane]

The amp draws like 1/2 amp at idle like its not fully turning on. An amp that size should draw a little current huh? Every once in awhile something clicks on the board then when I disconnect power it clicks again but very queitly and does not do it everytime. Strange.............

 

[seankane]

R206 and R306 read 0.00 VDC

 

[Perry Babin]

Is the amp producing rail voltage?

 

[seankane]

Is the amp producing rail voltage?

Yes -56 vdc on the gate and source of all IRF640 and +56 vdc on the gate and source of all the IRF9640

 

[Perry Babin]

Did you check the regulated voltage on the op-amps?

 

[seankane]

Did you check the regulated voltage on the op-amps?

No I did not.

Correct me if I am wrong

Pins 1 & 7 are audio in and out ?

Pins 4 & 8 are the power supply pins ?

Pins 2 & 3 and Pins 6 & 7 are the regulated voltage ?

 

[Perry Babin]

The voltage regulators feed the power supply pins (4 and 8). 1 and 7 are the outputs. The rest are the various inputs.

 

[seankane]

The voltage regulators feed the power supply pins (4 and 8). 1 and 7 are the outputs. The rest are the various inputs.

So checking the regulated voltage I would test pins 4 & 8 which are the power supply pins? Those need to have at least +/- 15 vdc ?

 

[seankane]

Pin 4 on all the op-amps have 3.5 vdc and pin 8 on all the op-amps have 18 vdc.

 

[seankane]

Pins 1 & 7 of all the op-amps except 2 have 18 vdc

The other 2 op-amps have 3.5 vdc on pins 1 & 7

 

[seankane]

I must have some shorted fets because upon adjusting the gains to max I have full rail voltage on the speaker terminals??

 

[seankane]

I have full + rail voltage on one channel and full - rail voltage on the other channel. What do you think about that??

 

[seankane]

I changed all the output fets just to be sure and still full rail voltage on speaker terminal, could a bad op-amp give the speaker terminals full rail voltage? What regulates the voltage to the op-amps?

 

[Perry Babin]

You need to determine why you don't have negative 15v on pin 4 of the op-amps. Check the LM337.