SPD3303X Hiccup

[ArcticGeek]

I tend to think that this might be a good candidate for a MOSFET-based bridge rectifier in order to reduce the heat dissipation, like what is shown here:

https://www.powerelectronictips.com/power-supply-circuit-mosfet-bridge-rectifier-gives-high-efficiency-for-low-voltage-high-current-ac-dc-supplies/

It would require a small PCB to be etched to hold the MOSFETs and other components.  I actually sold my SPD3303X-E some time ago, but if I still had it I would be tempted to make up a small board to replace the bridge.  This would get rid of the heat almost completely so you wouldn't have to worry about surrounding parts getting too warm.

Food for thought.

Cheers,

[tautech]

I tend to think that this might be a good candidate for a MOSFET-based bridge rectifier in order to reduce the heat dissipation, like what is shown here:

https://www.powerelectronictips.com/power-supply-circuit-mosfet-bridge-rectifier-gives-high-efficiency-for-low-voltage-high-current-ac-dc-supplies/

It would require a small PCB to be etched to hold the MOSFETs and other components.  I actually sold my SPD3303X-E some time ago, but if I still had it I would be tempted to make up a small board to replace the bridge.  This would get rid of the heat almost completely so you wouldn't have to worry about surrounding parts getting too warm.

Food for thought.

OTOH, any diode or bridge run near to max rating will produce heat.
Like most design these days components get pushed where once designers were much more conservative....which aided longevity/reliability.

Instead of a 2A rated bridge, latest HW runs an inline package of maybe double the rating...maybe pics I took of them display the device # IDK.

Edit to add
The updated inline bridge in a unit I have here is KBU1010, a 10A 1kV bridge.
https://www.mouser.com/datasheet/2/1451/kbu1010-3477620.pdf

[mawyatt]

We replaced the OEM rectifier with a 4A version that's in a flat plastic pack (like the new PCB version). Bent the leads to arrange them like the OEM version and fit directly to PC. This is higher off the PCB but should give better thermal results than the smaller circular OEM bridge rectifier.

Getting the OEM rectifier out was the most difficult part, everything else wasn't difficult. These things are built like tanks and not difficult to disassemble. The banana sockets are solid chunks of metal bolted directly to the PCB, looks like they could handle 100s of amps, it's a shame they didn't get the socket depth and spacing correct. Hopefully the new 4000 series fixed this, but hope they kept the massive metal shaft that bolts to PCB connection. 

Results are OK so far, will let run for a few days/weeks.

Best,

[tautech]

We replaced the OEM rectifier with a 4A version that's in a flat plastic pack (like the new PCB version). Bent the leads to arrange them like the OEM version and fit directly to PC. This is higher off the PCB but should give better thermal results than the smaller circular OEM bridge rectifier.

Yes this was the HQ recommended rework method that while very achievable, is an ugly bodge IMO and very never keen on it, so have always fastened the bridge remotely and made a short wire loom to it.

Others might like to see any pics Mike unless it's already a closed case......

[mawyatt]

Didn't look that bad. It's all closed up now and back on rack.

Best,

[mawyatt]

Okay, took the supply down and reopened.

BTW ran overnight without a Hiccup

Rob, here's a few images of the Bridge Rectifier replacement.

These supplies take a lot of flack, and mostly justified IMO (banana terminal spacing and plug engagement, quirky UI, and now the rectifier issue), but do provide a good, stable, clean, accurate output that is really good in this price class, and really like the bright display with crystal clear large numerics.

Once calibrated they produce accurate stable outputs in both current and voltage, after all that's what a good supply is supposed to do!! In fact what led us to rediscover the "Hiccup" was a dead garage door opener, we had replaced the battery recently and now dead again. First suspect was bad battery, yep it was dead but why as just replaced? Hooked up 3303X set to 3.0 volts and 10mA current limit to battery holder, the 3303X showed a 1mA current drain when Opener was OFF?? Checked current with KS34465A to verify 3303X 1mA reading, yep was ~1mA. Tried cleaning the Opener, but same 3303X 1mA reading OFF state result and no need to verify with DMM.

Still believe these are the best value at this price (especially with "expansion"), sure there are "better supplies" like the GPP-4323 and new SPD4000 series, however these are higher priced.

Best,