# What Diode have I here?

I am trying to figure what is with my broken power adapter (230V AC -> 12V + 5V DC at both 2A).

After checking the fuse, now I extracted two heavily cooled diodes, which could be the cause. But I simply can't figure out what diodes that are.

They are standard shaped (black cylinder, one end has the silver mark), 9mm long and 5 mm diameter, the connector wire is 1.1 mm diameter. On it I find two lines:

SR 8D

SB 54.0

I have performed some quick measurements, which are confusing me. I found a 3300 ohm resistor and plugged them at 2.7V. The voltage drop at the diode was 0,16V ( 2.7V if reversed) With another 220 ohm resistor it was similar.

Maybe the resistor values I am using are too high (the voltage is too low) to make useful tests...

How can I find out if they are OK or broken, and what type of diode do I have here?

If you look at the graph, in the link I posted, named: FIG. 3, you can see that the forward voltage of 0.16V is correct for the ammount of current through it: $I=\frac{2.7}{3300}\approx 1mA$.