Rectifier Lead Length

[Logistics]

I just found a couple more Antec PP-303X supplies in my garage, which I will recap and use in my vintage PC's, but one of the things I noticed was that the bridge rectifiers (that is what they are, correct?) are raised off the PCB quite a ways, and it was always my understanding that in a discrete bridge rectifier (made with actual Schottky's, for example) you had to be very critical about lead-length to make it work optimally.

So it stands to reason that the integrated unit should sit right AT the PCB, rather than way up in the air, plus cock-eyed so some leads are longer than the others. Or is this by design and serves a purpose?

I've uploaded an old pic of a PP-303X I recapped, the bridge-rectifier in question.

[stj]

Re: Rectifier Lead Length

that's the mains input, the frequency is only 60Hz so the lead length means nothing.

having said that, if you look close you will see that they did that because the holes in the board are slightly more spaced out than the rectifier they fitted.

long leads help keep any heat from reaching the soldering anyway.

[goontron]

Re: Rectifier Lead Length

I just found a couple more Antec PP-303X supplies in my garage, which I will recap and use in my vintage PC's, but one of the things I noticed was that the bridge rectifiers (that is what they are, correct?) are raised off the PCB quite a ways, and it was always my understanding that in a discrete bridge rectifier (made with actual Schottky's, for example) you had to be very critical about lead-length to make it work optimally.

So it stands to reason that the integrated unit should sit right AT the PCB, rather than way up in the air, plus cock-eyed so some leads are longer than the others. Or is this by design and serves a purpose?

I've uploaded an old pic of a PP-303X I recapped, the bridge-rectifier in question.

What do you think this is, a tuned circuit? It's a mains rectifier, not a ham radio..... Heck, it's not even being used as a reference source! It doesn't care if you feed it DC, 60hz, 120hz, 400hz, 800hz, the ass end of a blown generator, or the bizarre half wave colorado was running off of during fire season a couple of years ago after too many lines went down.

[Logistics]

Re: Rectifier Lead Length

What do you think this is, a tuned circuit? It's a mains rectifier, not a ham radio..... Heck, it's not even being used as a reference source! It doesn't care if you feed it DC, 60hz, 120hz, 400hz, 800hz, the ass end of a blown generator, or the bizarre half wave colorado was running off of during fire season a couple of years ago after too many lines went down.

I can see by the tone of your post that you belong in FYAD.

[mariushm]

Re: Rectifier Lead Length

Like others said ... the long leads don't matter on mains rectifier. It matters a lot on output capacitors or anything running at high switching frequency, where the leads can act as super tiny inductors messing things up.

One one hand, the longer leads can act as tiny heatsinks dissipating some heat from the rectifier and maybe if the rectifier is higher it's in a better area for airflow, keeping it cooler. But on the other hand, if the copper traces on the pcb are wide enough, the traces themselves can act as a better heatsink than then leads so then it makes sense to have the leads shorter.
In this application, the rectifier won't heat up enough to matter either way how you solder it.

I would just bend the rectifier a little to point away from the mains capacitor, no reason why you'd subject one of those caps to additional heat if it's possible to avoid that.

ps. Short leads would also matter if you're dealing with high currents. With high currents, thin leads may act as fuses and may burn up, or there may be shorts if the power supply eventually becomes so dirty that dust deposited on the leads would cause electric arcs between leads. Not the case with the 1-3 A currents such bridge rectifiers see on average.

[goontron]

Re: Rectifier Lead Length

I can see by the tone of your post that you belong in FYAD.

No, im being a wtftmnswse
(WhatTheFuckThatMakesNoSenseWhatSoEver)

[budm]

Re: Rectifier Lead Length

'One one hand, the longer leads can act as tiny heatsinks dissipating some heat from the rectifier and maybe if the rectifier is higher it's in a better area for airflow' +1.
Look at the NOTES in the spec sheet regarding to Thermal resistance and lead length, heat sink, Ta, If, etc..