Hey WileE, sorry for not responding sooner, I just moved to California and between that work, have had no time to hack... I'll get some more explicit instructions together.wileE wrote:I made before & after measurements with my Spyder. I would never claim to be able to see a difference of 20 nits.
How exactly would I do that? Dont assume that I know anything about what these parts I solder actually do. Complete dummy where electronics are concerned.xiphmont wrote:You can get the max brightness back by bumping down the sense resistance value a bit if you want.
That's worrisome. Some of the other boost kits need LEDs in groups of >=10, but Fancyboost should not be of them. If the LEDs were not going out, there was either some misassembly or damage to the driver chip. The Fancyboost has a ton of fault sensing on the outputs, but I'm not sure how well protected the input are...Having problems with the PWM mod on older fancyboost kits. Flicker is still visible after the mod.
1. Kit from 2013. Has the same layout as in the picture from FryPpy. Was also ordered for X61T, and delivered for X61.
When still on the X61 board this kit had the problem that the LED did not completely shut off when the charger was plugged in. When connected to a strip with groups of 8 and 9 LED, only the groups with 9 LED would turn off.
(as an example, I had a devil of a time in my designs with the TPS92510 because it turned out I had a transient coming in over the EN input that was over 5V for a few nanoseconds, and that was enough to damage the chip permanently. It _seemed_ to still work, but the CS input's bias current jumped from 100nA to a few hundred uA, enough to cause the circuit to malfunction slightly.)
Hm, if it stayed that way, I'd have thought 'oh, different rev of the driver, different behavior'. But having the problem magically disappear...This problem went away when I put the driver board on a inverter board that I modified myself. Never found out where the problem was.
A mechanic friend of mine used to say "Nothing ever fixes itself. Whatever broke either froze up, or fell off."
The mod changes the PWM frequency from 200Hz to 24kHz. So the flicker is still there, but the frequency is 100x faster, usually enough to pass even the pencil test. Is it actually running slower than that? Was this a kit that properly shut off LEDs before modding?Now I did the PWM mod, and the flicker is still visible, but also visibly faster. Not sure if it is better or worse now.
Oh, or do you mean flicker as in not PWM flicker, but brightness instability? Man, I wish I had a scope trace of the voltage across the sense resistors...
That does sound like something is going wrong. There's a lot of glare in your pic of the mod, hard to see the traces and connections clearly (though I do not see any obvious problem). I see above you've already done this mod successfully to other versions of the kit, right? It's just the 'older'/alternative layouts that are giving trouble?2. Kit from 2012. Has a completely different connection to the LED strip. And was delivered with a flexible LED strip with 36 LED.
Flicker was much less than with the 2013/14 kits.