Opamp DC offset

jnxw2 · 21st May 2003, 05:04 PM

As a simple project I decided to so a simple preamp using high speed unity gain opamps as line drivers. One channel seems to work fine but on the other one there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct, can anyone think of what the problem might be? Could it be that the chip is somehow damaged?

Any suggestions greatly appreciated

jnxw2

Tube_Dude · 21st May 2003, 05:44 PM

Quote:

there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct,

Are you sure that this 7 volts are not in the source that is driving the + Vin pin?

If not...

Quote:

Could it be that the chip is somehow damaged?

yes...that's possible...

Cheers

jnxw2 · 21st May 2003, 06:06 PM

Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input.
Also dont know if it is important or not but it is a current feedback opamp

jnxw2

Tube_Dude · 21st May 2003, 06:28 PM

Quote:

Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input

And the inverting input is at 0 Volts?

jnxw2 · 21st May 2003, 06:41 PM

Thats right, the inverting input is at 0V as is output.

jnxw2

janneman · 21st May 2003, 06:45 PM

We are really groping around in the dark here. A schematic (even rudimentary, hand drawn) would help YOU immensely.

Jan Didden

Tube_Dude · 21st May 2003, 06:47 PM

Sorry...bad news...the Ic is dead!

It will rest in peace!!!

Amen!

janneman · 21st May 2003, 06:53 PM

Not to spoil your party, but how do you rate the chance that the new opamp you put in will also die untimely? Where's the f<]u*#c*#k@i^%n@!g schematic??

Jan Didden

jnxw2 · 21st May 2003, 07:15 PM

Yeah i was kind of coming to that conclusion aswell

Here is the diagram.

jnxw2

Werner · 22nd May 2003, 07:01 AM

You connected the - input to ground???

21st May 2003, 05:04 PM	#1
jnxw2 diyAudio Member Join Date: Sep 2002 Location: London, UK	Opamp DC offset As a simple project I decided to so a simple preamp using high speed unity gain opamps as line drivers. One channel seems to work fine but on the other one there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct, can anyone think of what the problem might be? Could it be that the chip is somehow damaged? Any suggestions greatly appreciated jnxw2

21st May 2003, 06:45 PM	#6
janneman diyAudio Member Join Date: May 2002 Location: Where Germany, The Netherlands and Belgium meet Blog Entries: 6	dc offset We are really groping around in the dark here. A schematic (even rudimentary, hand drawn) would help YOU immensely. Jan Didden

21st May 2003, 06:47 PM	#7
Tube_Dude diyAudio Member Join Date: Mar 2002 Location: Aveiro-Portugal	The dead Ic... Sorry...bad news...the Ic is dead! It will rest in peace!!! Amen! __________________ Jorge

21st May 2003, 06:53 PM	#8
janneman diyAudio Member Join Date: May 2002 Location: Where Germany, The Netherlands and Belgium meet Blog Entries: 6	offset Not to spoil your party, but how do you rate the chance that the new opamp you put in will also die untimely? Where's the f<]u#c#k@i^%n@!g schematic?? Jan Didden

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21st May 2003, 06:06 PM	#3
jnxw2 diyAudio Member Join Date: Sep 2002 Location: London, UK	Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input. Also dont know if it is important or not but it is a current feedback opamp jnxw2

21st May 2003, 06:41 PM	#5
jnxw2 diyAudio Member Join Date: Sep 2002 Location: London, UK	Thats right, the inverting input is at 0V as is output. jnxw2

22nd May 2003, 07:01 AM	#10
Werner diyAudio Member Join Date: Jan 2002 Location: Belgium	You connected the - input to ground???

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