Opamp not working properly

[ants]

Yes the 555 output was being shorted. I can't actually see it in the schematic but I just checked the board layout. The error Eagle gave me was 'overlap'. I had an air wire which for some reason was connected when it wasn't actually supposed to be there at all.

I've sent for another board along the same lines, there are no overlap errors. I'm fairly confident I will have the 555 timer and opamp working now, but I've also added a DC-DC booster so I'm expecting trouble with that the next time

 

[keith1200rs]

I don't know about the overlap error - you should be able to find it from the coordinates, but you have a fundamental logical error with the pot as it is drawn. When you turn the wiper to the ground end it will short out the 555. You need to change it as I described earlier.

Keith

 

[ants]

I'm hoping the overlap and logical error are the same thing. I've attached a pic of the layer as I'd have preferred it. Is there a good way of taking unwanted traces off a board?

Thanks,

Ant.

 

[keith1200rs]

No, you still have the logical error - pot wiper to the 555 output instead of the opamp input.

To rip up tracks - use the 'rip' command, either from the command line or there is an icon on the left. However, in this case you need to fix the schematic first.

Keith

 

[ants]

Ah yes. I see that now. The same error is on the next board I've ordered from PCB Pool too. I'll have to do without the volume control and fix it on the revision after.

I think the technique for fixing boards is a scalpel to break traces and a silver pen to make traces. Doing that will be interesting

Thanks for the input.

Ant.

 

[keith1200rs]

It is easy enough to fix with a couple of track cuts. I use a small bladed craft knife (small Stanley knife) to cut tracks - genuine scalpals can get easy to snap. Then use single core insulated wire to make the proper connections.

Keith

 

[ants]

I've got that. Thanks.