PPI PCX-2400

brandes.cm · 23rd November 2011, 01:35 AM

Working on this amp, right channel has +19Vdc on it and the left has -17Vdc. The left channel has the top part clipped off. The right channel has a signal riding on a dc level.

Reading other threads I found a schematic for the ceramic boards, what should the signal coming into pin 3 and 4 be.

Attached is a photo of the pc board. Are the drivers Q9, Q10 on the ceramic board?

Perry Babin · 23rd November 2011, 01:47 AM

Measure the voltage again but this time, place the black probe on one of the non-bridging speaker terminals.

The signal on pins 3 and 4 should be audio with essentially no DC.

Do you have the proper supply voltage on both power supply pins of the op-amps?

Do you have the proper supply voltage on both power supply pins of the driver board?

Do you read 100 ohms for each placement (A and B) on the following image?
http://www.bcae1.com/temp/ppidriverb...roverlay01.swf

brandes.cm · 23rd November 2011, 02:01 AM

+20Vdc on right channel
-4Vdc on the left
L+ to R- is the bridged terminals I believe.

+-13 on the op-amps

+-60 on pins 1 and 15

The right channel has no 100 ohm readings and the left channel "B" reads 100 ohms only.

Perry Babin · 23rd November 2011, 02:19 AM

Install a 100 ohm resistor as is shown for the open resistor.

You can determine which ones are the non-bridging terminals by finding the ones that read 0 ohms between them.

brandes.cm · 23rd November 2011, 02:49 AM

The left channel is functioning now.
The right channel is sitting with 55Vdc on it and the ceramic module is getting extremely hot. This channel has the signal riding on a dc level on pins 3 and 4 also.

Perry Babin · 23rd November 2011, 02:59 AM

Check the small predriver transistor on the top right corner of the driver board. Is it shorted or leaking?

Compare to the other board if you can't tell if it's leaking.

Have you checked the large transistors on the driver board?

brandes.cm · 23rd November 2011, 03:06 AM

Looking at the pic you sent, the two directly above the large transistors? Comparing between the two boards, 3 of 4 measure shorted from B-E(two pins on same side). I could have the probes touching though.

brandes.cm · 23rd November 2011, 03:26 AM

MMBTA06 and MMBTA56 should sub fine for these parts, correct?

Perry Babin · 23rd November 2011, 04:46 AM

Yes. I've used those as subs.

brandes.cm · 23rd November 2011, 12:26 PM

Would hot air with solder paste be the best way to solder these down?

23rd November 2011, 01:47 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Measure the voltage again but this time, place the black probe on one of the non-bridging speaker terminals. The signal on pins 3 and 4 should be audio with essentially no DC. Do you have the proper supply voltage on both power supply pins of the op-amps? Do you have the proper supply voltage on both power supply pins of the driver board? Do you read 100 ohms for each placement (A and B) on the following image? http://www.bcae1.com/temp/ppidriverb...roverlay01.swf __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

23rd November 2011, 02:19 AM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Install a 100 ohm resistor as is shown for the open resistor. You can determine which ones are the non-bridging terminals by finding the ones that read 0 ohms between them. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

23rd November 2011, 02:59 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Check the small predriver transistor on the top right corner of the driver board. Is it shorted or leaking? Compare to the other board if you can't tell if it's leaking. Have you checked the large transistors on the driver board? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

23rd November 2011, 04:46 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Yes. I've used those as subs. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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23rd November 2011, 02:01 AM	#3
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	+20Vdc on right channel -4Vdc on the left L+ to R- is the bridged terminals I believe. +-13 on the op-amps +-60 on pins 1 and 15 The right channel has no 100 ohm readings and the left channel "B" reads 100 ohms only.

23rd November 2011, 02:49 AM	#5
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	The left channel is functioning now. The right channel is sitting with 55Vdc on it and the ceramic module is getting extremely hot. This channel has the signal riding on a dc level on pins 3 and 4 also.

23rd November 2011, 03:06 AM	#7
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Looking at the pic you sent, the two directly above the large transistors? Comparing between the two boards, 3 of 4 measure shorted from B-E(two pins on same side). I could have the probes touching though.

23rd November 2011, 03:26 AM	#8
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	MMBTA06 and MMBTA56 should sub fine for these parts, correct?

23rd November 2011, 12:26 PM	#10
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Would hot air with solder paste be the best way to solder these down?

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