I was able to duplicate these results on 2 units by paralleling a 2.2k across the resistor between VFB and Vout for each TPS53355 switcher (8 per board). That's all I did, I didn't upgrade my firmware or change voltage settings in firmware (not available in mine and read that the setting doesn't do anything anyway). I tested efficiency at different frequencies and the best results I achieved are:
Unit 1: 0.645 J/Gh @ 193 MHz
Unit 2: 0.625 J/Gh @ 175 MHz
At $0.13/kWh and current BTC price I'm profitable again, but just barely.
I have 3 more S3+ units to convert and did notice that one of the boards is a different (newer) version. I don't see the TPS53355 switcher on it or a voltage divider circuit that I can modify to change the hashing chips voltage. Any info on the newer board appreciated. I can post pictures of mod and detailed drawing if anyone is interested.
I've got a dozen (12) S3's and a similar amount of C1's.
Need to do this mod on all of them.
I have strong electronics and soldering skills.
So soldering in a 2.2K 1% 1/8W metal film resistor across the 2.088K SMD resistor isn't an issue. A time consuming PITA, but easily doable.
Understand everything (and the theory behind it) in the post except the "HW .003 20 ment. idle".
Is that a S/W configuration thingy?
WTF over? LOL.
Thanks in advance.
I think the "HW .003 20 ment. idle" is referencing the hardware error rate/typo. I also used 1/8 W resistors and it is a PITA. I had a friend who works with me and is a certified solderer do using his soldering station with microscope setup. He said it was more difficult than he expected and had to tin the leads and really clean the boards to get the solder to take. Since then also modified 2 more units; best efficiency depends on frequency setting and they range from 125 to 193 MHz and of course they generate a lot less heat.
