Deciphering Asymmetric Power Distribution on Speedo 402 Brown Line

kdthomas · Oct 10, 2014

OK, so above is the power distribution diagram from the unit. This thing is making me crazy. Nuts ... I'm literally up nights with this thing. I'm like Richard Dreyfus in Close Encounters ... You may think I'm kidding. I'm not.

The symmetrical thing is not a problem. All the juice is divided across all the lights. 400 w/s total, 2 lights ... 200 w/s per light. 4 lights, 100 w/s per light. Got it.

Asymmetric though, I don't get. Look at the 2-light row, first example. 200 w/s shared among plugs 1&2, then 100 w/s on 3 or 4 ... where'd the other 100 w/s go? Also, we get 2x200 on plugs 1&2 (that one actually makes sense). But then 2x100 on plugs 3&4 where the other 200 w/s go?

Am I crazy? What am I missing? What mathematical model is this based upon?

tirediron · Oct 10, 2014

Don't worry about the math model, just accept it. Seriously. I have no idea where the "lost" power goes, I just read the chart and move my lights accordingly. The idea is that it allows you to have different power outputs on your lights without having to move them.

Derrel · Oct 10, 2014

The D402 has mulitiple capacitors inside, not just one, big single capacitor, so if one has two lights plugged into outlets 3 and 4, and the power distribution switch is set to Asymmetrical mode, the system distributes only a total of 200 Watt-seconds to the "back channel". The capacitor can store up to 400 Watt-seconds' worth of energy, but it does not need to "dump" all of it with every firing. There is no "lost" power. I'm not sure what you are talking about, really.

I own a couple D402's, as well as a D202, a D604, and a D1602. The D1602 is a nice pack to own. It has full, half, and also the old-school 200 Watt-second "Low" option, which means that of 1600 total, stored Watt-seconds, the pack can siphon off a mere 200 W-s, or 1/8 power, allowing even an old-technology pack to fire at blistering speed when in Low mode.

With the D402, there really is no "lost" power in Asymmetrical mode. If you want 200 W-s each from two heads, plug them into outlets 1 and 2; if you want only 100 Watt-seconds from 2 heads, plug them into outlets 3 and 4.

The other, unstated aspect here is that when symmetrical or asymmetrical also affects the MODELING LIGHT brightness, which gives you options. If you want two lights at 100 W-S, you can ALSO turn the pack to Half power, and use outlets 1 and 2 in Symmetrical mode, and keep the modeling lights BRIGHT....OR, you can plug the same lights into outlets 3 and 4 and go to Asymmetrical, which drops the modeling lights down.

There is no mathematical model you are missing, you're just not familiar with the way the system actually works. When you combine a WEAKER pack with a higher-power pack, or use three or four lights, THEN the modeling lamp brightness options start to make more visual sense,and are actually pretty useful in gauging lighting ratios by sight.

This system was designed around 40 years ago,more or less. It's just old-school. It's very basic and reliable and straightforward.

kdthomas · Oct 12, 2014

Studying manual one more time. Then .... wait ... I literally sit bolt upright in bed (I swear I'm not making this up)

the theme from 2001 starts playing:
BUM-BA BUM-BA BUM-BA BUMMMMMMM
daa ... Daaaa .... DA DAAAAAAAAAAA !!!!!!

I start grunting and hopping around the monolith and screeching.

All the possible combinations are right there -- on the diagram -- for 4 lights spread across 2 sets of two plugs!!!

I fling the bone in the air! I have opposable thumbs! I can make tools, and space shuttles, and lawn furniture!

Yes ... Yes! ... we can have zero, one or two lights plugged into a set ... that's three possibilities per set, and two sets, three squared is nine, and they omitted the case of zero and zero.
1 and 0
0 and 1
1 and 1
2 and 0
0 and 2
1 and 2
2 and 1
2 and 2