LM4780 - ouput = 4.4v - PB! HELP!

aceditnanar · 25th June 2006, 08:25 PM

Hello,

I did two parallel LM4780 board like audiosector, and I have made the same schematic and the same composants, but when i put the current, i have 4,4v on the 2 outputs.. so it's a pb of composants? no?
(with the pcb of pinkmousse)

you can see my topic, and my schematic... I don't know what i must do now...

what is pb.??

help please..

http://www.homecinema-fr.com/forum/v...7311#169927311

thanks a lot for your help...

Netlist · 25th June 2006, 08:44 PM

Does the offset disappear with a dummy load as suggested at the other forum?
Also, measure every resistor and confirm their value is correct.

/Hugo

aceditnanar · 25th June 2006, 09:02 PM

ok, tank you, when I have a resistorI put it..

but this offset is not good normaly...
no?
I confirm that all resistors have good values

thank's for this suggestion...

others?

aceditnanar · 26th June 2006, 07:59 AM

does somebody know from where that can come? a value which influences the output in an abnormal way? thank you

Wynand · 26th June 2006, 08:52 AM

Can you maybe post a picture of your pcb so we can see?

aceditnanar · 26th June 2006, 11:51 AM

yes, I post a picture this evening...

aceditnanar · 3rd July 2006, 04:10 PM

hello everybody

It' was just a pb of starground and my input wasn't connected to the ground to test my systeme...

with my new start, I have 2.2mv and on the other board, 19.2mv...

it's all right...

I post my picture when I could..
and i want to changed my post to a post of my GC

by

25th June 2006, 09:02 PM	#3
aceditnanar diyAudio Member Join Date: Apr 2006 Location: neer lyon	ok, tank you, when I have a resistorI put it.. but this offset is not good normaly... no? I confirm that all resistors have good values thank's for this suggestion... others? __________________ "if it were necessary to build asylums for the idiots, you imagine the size of the buildings" - TaisToi! (french movie)

26th June 2006, 07:59 AM	#4
aceditnanar diyAudio Member Join Date: Apr 2006 Location: neer lyon	does somebody know from where that can come? a value which influences the output in an abnormal way? thank you __________________ "if it were necessary to build asylums for the idiots, you imagine the size of the buildings" - TaisToi! (french movie)

26th June 2006, 11:51 AM	#6
aceditnanar diyAudio Member Join Date: Apr 2006 Location: neer lyon	yes, I post a picture this evening... __________________ "if it were necessary to build asylums for the idiots, you imagine the size of the buildings" - TaisToi! (french movie)

3rd July 2006, 04:10 PM	#7
aceditnanar diyAudio Member Join Date: Apr 2006 Location: neer lyon	hello everybody It' was just a pb of starground and my input wasn't connected to the ground to test my systeme... with my new start, I have 2.2mv and on the other board, 19.2mv... it's all right... I post my picture when I could.. and i want to changed my post to a post of my GC by __________________ "if it were necessary to build asylums for the idiots, you imagine the size of the buildings" - TaisToi! (french movie)

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25th June 2006, 08:25 PM	#1
aceditnanar diyAudio Member Join Date: Apr 2006 Location: neer lyon	LM4780 - ouput = 4.4v - PB! HELP! Hello, I did two parallel LM4780 board like audiosector, and I have made the same schematic and the same composants, but when i put the current, i have 4,4v on the 2 outputs.. so it's a pb of composants? no? (with the pcb of pinkmousse) you can see my topic, and my schematic... I don't know what i must do now... what is pb.?? help please.. http://www.homecinema-fr.com/forum/v...7311#169927311 thanks a lot for your help... __________________ "if it were necessary to build asylums for the idiots, you imagine the size of the buildings" - TaisToi! (french movie)

25th June 2006, 08:44 PM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	Does the offset disappear with a dummy load as suggested at the other forum? Also, measure every resistor and confirm their value is correct. /Hugo

26th June 2006, 08:52 AM	#5
Wynand diyAudio Member Join Date: Mar 2005 Location: Cape Town	Can you maybe post a picture of your pcb so we can see?

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