In addition to collecting lighting related things, I also collect fire alarms (technically lighting related as well. Among my collection I have many devices that contain strobes. Most of them work, but I do have two that don't work that I would like to get working. Specifically, a Simplex 2903-9150 120V strobe plate, and a Space Age Electronics A32 white strobe plate. Does anyone on this site have experience in strobe circuits or repairing them?

I don't know about fire alarm strobes, but I have some strobe light drivers and I know how they work. Usually they consist of a small step up transformer, the primary of which is driven by the discharge of a small capacitor. This sends an HV pulse to the antenna outside the tube which discharges a larger capacitor through the tube. I would say the most likely thing to go wrong is in the triggering circuitry. This is sometimes done with a neon indicator, but could be more complicated with fire alarms if they are supposed to strobe synchronously. Usually they aren't that complicated, just start checking the different components until you find a bad one. Do you have a picture of the board?

@Ash , @Medved , and @RRK are the guys that would have a good idea of whats up..

Strobe circuits are usually pretty simple though.

You will need to post pictures of the PCB itself both front and back at minimum. Cant really tell whats going on from model number alone.

Small flashtubes are typically powered by discharging an electrolytic capacitor with circa 300V voltage.  Charge circuit is some kind of current limiter, voltage doubler I suppose in US with 120V mains, or a small step-up converter for DC or battery power. Like already was said, triggering is done with a small pulse transformer, generating short spikes of a few kilovolts by discharging a small circa 0.1 uF capacitor to transformer primary via some negative resistance element. Negative resistance may be a neon bulb, SIDAC, SCR etc.

You check ~300V at the capacitor first, if present, triggering circuit shall be verified to work. HV transformer may get shorted, obviously.