Building SKBOWE Batch 1 - SKBOWE PWM filter

Long day of work (8AM – 7PM) but Batch 1 is nearly complete! Enjoy the pics…

Last night, I was able to get all the resistors and the flyback diodes (R1 and D3) installed and leads trimmed. I also got the wires soldered on, and ended with this lovely ball.

This is where I started this AM – a giant ball of wire… Each board has the five leads, R1 and D3.

This AM I got the primary wires trimmed, and capacitors stuffed, soldered, and trimmed… This is a lot of capacitors – 2,132,000uF aka 2.132 Farads to be precise.

All capacitors soldered to the boards — All 26 pairs with their caps soldered on. This is a lot of capacitors! (2,132,000 uF aka 2.132F to be precise).

Next came the diodes. As I had suspected laying out the new PCB, and confirmed when building #002, the heat sink (anode) of D2 does overlap the leads of D1. This shouldn’t be an issue if it’s assembled properly, but once the potting goes it it’s impossible to verify or adjust so I added some UHMWPE tape over the leads of D1 just to be safe.

diodes ready for stuffing — Diodes with leads bent and ready for stuffing. Note tape on leads of D1. This is not all of them, I had already done 16 or so when I remembered to take a picture.

By 3PM everything was soldered, trimmed, and ready to go. I have a lot of respect for the poor souls at Foxcon who do this all day, every day, with much smaller components. Wow.

Next I cut the wire pen into the enclosures. Took a little extra time to jig it up but it was well worth it.

Enclosures cut and ready to go — Enclosures cut for wire passthrough.

Finally, and this was the most physically exhausting part, assembling the PCB assembly, heatsink, and insulator into the enclosure. But 2 hours later, sweet victory:

SKBOWE batch 1 ready for potting. The insulator saves about 800mL of potting, a minimum of 1200mL will be required (assuming no leaks, spills, etc) to fill these boxes.

Also jigged up a workstation for potting so spills are easier to contain. Just a piece of plywood with the right shape cut out.

Jig for potting holds two SKBOWE units (one pair) and has disposable parchment paper on top to help contain spills & overflow.

As much as I want to jump in to the potting, I’m mentally wiped and will almost certainly make a mistake. Better to wait till tomorrow.

The 11 hours I was working today I left SKBOWE #002 running on the testbench, powering Morimoto XB55 at worst case DRL duty cycle (50%). The temp never broke 90°F (ambient +20°) anywhere on the enclosure. That’s really cool (excuse the pun), especially compared to the only other error eliminator that seems to (barely) work on 82Hz PWM, which had a +80°F rise after an hour at 80% duty. For comparison, the XB55 was hanging around 140°F

SKBOWE temperature after 11 hours of operation does not exceed 90F (+20° above ambient) anywhere on the enclosure. This is excellent.

XB55 after 11 hours, hanging around 130°F

One thought on “Building SKBOWE Batch 1”