RL151s are tough diodes

[Trinite]

I have an old power brick in which the device it was attached to shorted out, taking the power brick with it. Or at least I thought. It was a bad short too, as you can see from the melted tip in the pics. When I opened it up, all the rectifying diodes (RL151) had gotten so hot that they had desoldered themselves from the PCB. The all tested good, so I resoldered them all and tested the unit. Got 12V on the output just as specified. Looks like some seriously tough components, especially compared to some you see today.

[Wizard]

Re: RL151s are tough diodes

Reason diodes did not short out is transformer's impedance is high that won't transfer enough current to cause silicon diodes to breakdown and short out.

Cheers, Wizard

[Trinite]

Re: RL151s are tough diodes

Well, looking at impedance, looks like the transformer can put out about 3A max, so that is about double the diodes' rated current. You're right, probably not enough to blow them, but still pretty impressive that they held up to high enough temps to desolder them from the PCB (200°C+ I'm guessing).

[kc8adu]

Re: RL151s are tough diodes

diodes have to be able to survive high temps.otherwise soldering would kill them.now if you want impressive heat survival an original p60 in an alr desktop.glued on heatsink fell off.got hot enough to melt solder and drop out of the board.socket and all.i cleaned it up,soldered the socket back in and it worked just fine!it was given up for dead by a local shop.got it free.

[Scenic]

Re: RL151s are tough diodes

pretty funky looking cap vent