PPI a600 channel

carlinux · 2nd June 2011, 07:46 PM

Hi I have a problem on a channel of this amp when I switch it on you hear a noise like fries accompanied by a slight hiss, which does not bother to play, but raising the maximum volume that the sound always almost tears while 'other channel has no problems playing the whole, I was advised to move the ceramic plates and acting on bias but nothing 's gonna change, I have no diagrams or other in order to understand what the problem is, anyone can' help me in this?
Thanks to all

Perry Babin · 2nd June 2011, 08:18 PM

Look at the attached image (link). You see two resistors. Place the meter (set to ohms) on the end points of each resistor. What is the resistance for each?

Do this with no power applied.

http://www.bcae1.com/temp/ppidriverb...roverlay01.swf

carlinux · 3rd June 2011, 06:51 AM

tnx Perry for quick reply i try this and write here a soon possible, but is possible this problem is a bad ground on car ?

carlinux · 3rd June 2011, 08:59 AM

hi i have tested the ceramic card my digital multimeter is to 20K and measure is 12.98 and decrease the same at other channel in the same points to pics you have post here..

Perry Babin · 3rd June 2011, 03:39 PM

It's not likely a ground problem if one channel works flawlessly unless the problem is a grounded speaker wire.

If the meter isn't auto-ranging, set it to the lowest resistance scale and measure across those points again.

carlinux · 4th June 2011, 09:36 AM

i have set the digital multimeter to 200 ohm and the measure point indicate to your image is 98 ohms the same measure is in the other card/channel

Perry Babin · 4th June 2011, 10:36 AM

If you read ~100 ohms, the resistors are likely OK.

Do you have an oscilloscope or a way to monitor/listen to the audio at various points in the circuit?

carlinux · 4th June 2011, 11:16 AM

sorry i not have a oscilloscope . but exist any way to test this ?

Perry Babin · 4th June 2011, 04:07 PM

If the problem is noise, you need to be able to either listen to the signal at various points in the signal chain or you need to be able to see the waveforms to see where the noise is being introduced.

Are you sure that the noise isn't due to dirty contacts or bad connections on the switches, potentiometers or RCA jacks?

carlinux · 11:27 AM

hi Perry i have solved this, i have reweld the pins to channel card/board ( your photo see a few weldind pins and maybe not make a good contact)and transistor and for now noise is vanished, now i test for 2-3 day, i hope is all ok .
tnx 4 u help, maybe one day i disturb you again for oscilloscope signal , first i buy a oscilloscope

.
tnx again

2nd June 2011, 07:46 PM	#1
carlinux diyAudio Member Join Date: Jun 2011 Location: Novi Ligure	PPI a600 channel Hi I have a problem on a channel of this amp when I switch it on you hear a noise like fries accompanied by a slight hiss, which does not bother to play, but raising the maximum volume that the sound always almost tears while 'other channel has no problems playing the whole, I was advised to move the ceramic plates and acting on bias but nothing 's gonna change, I have no diagrams or other in order to understand what the problem is, anyone can' help me in this? Thanks to all

2nd June 2011, 08:18 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Look at the attached image (link). You see two resistors. Place the meter (set to ohms) on the end points of each resistor. What is the resistance for each? Do this with no power applied. 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

3rd June 2011, 03:39 PM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It's not likely a ground problem if one channel works flawlessly unless the problem is a grounded speaker wire. If the meter isn't auto-ranging, set it to the lowest resistance scale and measure across those points again. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

4th June 2011, 10:36 AM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If you read ~100 ohms, the resistors are likely OK. Do you have an oscilloscope or a way to monitor/listen to the audio at various points in the circuit? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

4th June 2011, 04:07 PM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the problem is noise, you need to be able to either listen to the signal at various points in the signal chain or you need to be able to see the waveforms to see where the noise is being introduced. Are you sure that the noise isn't due to dirty contacts or bad connections on the switches, potentiometers or RCA jacks? __________________ 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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3rd June 2011, 06:51 AM	#3
carlinux diyAudio Member Join Date: Jun 2011 Location: Novi Ligure	tnx Perry for quick reply i try this and write here a soon possible, but is possible this problem is a bad ground on car ?

3rd June 2011, 08:59 AM	#4
carlinux diyAudio Member Join Date: Jun 2011 Location: Novi Ligure	hi i have tested the ceramic card my digital multimeter is to 20K and measure is 12.98 and decrease the same at other channel in the same points to pics you have post here..

4th June 2011, 09:36 AM	#6
carlinux diyAudio Member Join Date: Jun 2011 Location: Novi Ligure	i have set the digital multimeter to 200 ohm and the measure point indicate to your image is 98 ohms the same measure is in the other card/channel

4th June 2011, 11:16 AM	#8
carlinux diyAudio Member Join Date: Jun 2011 Location: Novi Ligure	sorry i not have a oscilloscope . but exist any way to test this ?

6th June 2011, 11:04 AM	#10
carlinux diyAudio Member Join Date: Jun 2011 Location: Novi Ligure	hi Perry i have solved this, i have reweld the pins to channel card/board ( your photo see a few weldind pins and maybe not make a good contact)and transistor and for now noise is vanished, now i test for 2-3 day, i hope is all ok . tnx 4 u help, maybe one day i disturb you again for oscilloscope signal , first i buy a oscilloscope . tnx again Last edited by carlinux; 6th June 2011 at 11:27 AM.

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