hi
hi ive been getting some help on more general points on this system,over on tech repair , for which im very grateful,
but i thought i,d give them a break, as this is a bit more straightforward and specific.

i have an op amp in circuit , it is reading. 4.1 volts on the inverting input.
4.37 volts on the non inverting input
and .zero volts on the output

thats with + 15.13 volts on the pos power supply pin and 14.3 volts 0n the neg power supply pin.

as its in a tricky place to get to, could someone please be kind enough to confirm that the op amp is faulty.
thank you.

 

I presume you mean -14.3V on the negative supply pin.
Either the amp is faulty or the connections or usage are incorrect in some way.
Which op-amp are you using?

 

hi
the op amp is the dual njm4580

forgot to mention --all voltages and signal voltages are dc,
and output not connected.

I presume you mean -14.3V

yes

 

The supply and input voltages are appropriate for this amplifier so we are back to a faulty chip or your connections to it. Check the pin connections in the datasheet for the particular package that you have and compare with your circuit. Check that your output is not short-circuited to ground.

 

A good op-amp in a defective circuit, the output usually sticks to one of the rails. That is, the output is stuck either to the highest or lowest voltage available. The exception is when they are oscillating. That makes most DC meters go a little crazy.

Check for oscillation. If it's all nice, clean DC, I'd say replace the chip. If the output is still wrong, then I was wrong.

 

what does "no output" mean?

 

TS said the output was 0V.

 

solved
put a new op amp in -working fine,
thank you

 

Triffic

 

solved.
changed opamp ,
good output now,
thank you