[Lost81]

Hi guys/gals,

Is there a difference between mounting the rectifier / filter cap assembly right side up (spades pointing down) or upside down (spades pointing up)?

I have a heat sink attached to the center diode and since heat migrates upwards, won't the heat heat up the solder joint instead of migrating into the heat sink?

My friend, who is an EE engineer, told me it doesn't matter, but I just thought I will ask those who had done it.

FWIW, my rectifier boards are sawn in half (monoblock configuration), so I have to drill 2 holes somewhere to mount the boards.

Thanks!


-Lost81

[Occam]

Check the direction of rotation as you flush your toilet first!!!!
If it rotates clockwise you must mount the circuit bord right side up, if counter-clockwise upside down. This has to do with the Corioliss force, and you don't want your electrons spinning in the wrong direction....

  I'm just yanking your chain...
Your  friend is correct, though I must confess I've never done a scientific comparison. Stressing a diode is going to blow it up prior to it getting hot enough to melt solder, if thats any consolation. While heat by convection goes upwards (actually its the heated air that going upwards), but heat by conduction doesn't care; it simply goes from hot towards cold, all things being equal.
My 55 has its ps board mounted upside down, and I've not noticed any problems other than a tendancy for the upstairs toilet to flush strangely...

[Malcolm Fear]

I've built several 55 watt AKSA's. PCB is upside down, with components underneath.
Never a problem.

[Greg Erskine]

Hi Lost81,

My AKSA PSUs are all upside down and I haven't had a problem. I've used heatsinks on the centre diodes and they only get slightly warm never hot. I have a feeling the heatsink may not really be necessary (on the AKSA 55 anyway).

Greg