Help please! GGG Rodent build question-what's going on here?

[Russ]

I just finished assembling a GGG's Rodent pcb and encased it, and have been unable to get it to fire up. I built it without the Mill. bypass components on the board- I'm using a 3PDT switch. BTW, before I continue, the wiring and componentry are 100% correct- I've checked and rechecked as well as retouching all the solder joints.
The problem is that the IC chip (a socketed LM308 from Steve at Small Bear) is getting hot. Is there the possibility that I've gotten a bad chip? It's about the only thing I haven't a spare to try. Any ideas?
Thanks, Russ

[aron]

Hmmm.... there's some kind of short. Obviously you are getting power to the thing.  Somewhere there's a short. I guess remove the chip and power down and then use your multimeter to see if any traces are connected which shouldn't be.

Also triple check your component values.

[Mark Hammer]

The GGG board for the Rodent is not the sort of layout that is ripe for solder bridges (at least not as ripe as some of the Tonepad layouts for the more component-intensive circuits), but it has a number of pads where there are several possible installation points for the same cap, depending on what size of part you want to use or can get.  Is it possible that you inadvertently connected some parts to the wrong places?

[R.G.]

"opamp getting hot" is almost always one of two things - either opamp plugged into socket backwards or output shorted.  Occasionally you'll get an opamp oscillating at ultrasonic frequencies and getting hot, which is a possibility if you used an LM301 and did not include the compensation cap or if the compensation cap is not well connected.

There are others, but those three will cover about 97% of cases.