I'm building a rat, or rodent actually from GG, and im getting a DC voltage leak somewhere.. My 9v rail should is like 1.3V.. Ive taken out every major cap that goes form this rail to ground and it doesnt change anything. Whe i take measurements w/o the IC in the rail is 9V as it should be.. what does this tell me as far as debugging? that the circuit up to the opamp is ok i assume.. and after should be ok because theres a different 9V tap.. Does this mean my opamp is bad? i only have one cuz its a $4 chip.. LM308..
any other suggestions? thanks
anyone?
would it be feasable to take out caps? if the caps on teh power rail werent there what would happen?
anyone? im getting 1.2V on the 9V rail.. when i take the IC out it reads fine.. im testing at the 47ohm resistor. i treid taking out C7 to break the circuit to eliminate anythign down the line.. didnt help so i guess the problem is before C7..
sounds like a short somewhere...is the IC in the right way?
Johan
It sounds like you have either a bad opamp or possibly a wiring error. I wouldn't think it's a bad cap but I don't have the circuit in front of me. OK just looked it up... If you still get the same result after removing C7 (and testing without anything in that position), then It's almost surely a bad chip or a wiring error. If you have a 741 around, give that a shot in the socket, but make the test quickly because you could blow it out if there is a solder bridge somewhere.
Best of luck!
Take care,
-Peter
hrm i scrubbed the traces w/ contact cleaner to remove any flux, etc so its really neat and clean looking. no traces are touching..
it must be a bad chip. blast! $4 and a good week shipping down teh drain
can i find that 741 at ratshack?
Look at the board under a bright light.. with a magnifying glass.. at different angles.
I SWORE I had a perfect board on my EasyVibe.. but lo and behold... at a certain angle - I could just see the TINIEST bit of copper bridging 2 traces... scraped it with an Xacto... and voila.. vibin'
'-)