Dragonmint B52 Fan speed issue.

[Jellyman]

Hello All,

Hopefully someone can help as I'm completely lost with my B52 Fan issue.
I have 2x B52's running with latest S11 firmware (not sure if this is a good idea or not although when I got the miners second hand they already had an older S11 firmware installed. Anyway I don't know how to downgrade.
So I had to change the fans as the old ones where making horrid sound so to be safe I replaced them with some spare new 4pin fans I have.
The B52's seemed to work ok until I tried to push them passed efficiency mode. As soon as I did this the hash boards overheated and shut down.
After investegating why I've found that when the software increases the fan speed it actually decreases the fan speed.
So when the fan is reporting 100% in the miner software the fan is 0% and when the software reports the fan as 10% the fan is running full speed.
I've tried fans from other miners and I've also done a factory reset but still I have this issue.
I have checked the fan wiring and it's correct (as said I've used working fans from my other miners) although they are not B52's.
This is affecting both my B52 miners.
I'm out of ideas can anyone help or has anyone experienced anything like this before.

Thanks

[Jellyman]

Ok... So after investigating more and comparing control boards between my B52's and my working S11 I see one noticeable difference.
My B52's look like they have been modified.. certainly the soldering does not look like anything a mining manufacturer would do.
2x additional components are soldered to the board.

I have no idea why this has been added and if it's this that's causing the fan speed issue.

My next question is how easy is it to fix the fan speed to say 60% on the dragonmint B52's SGminer software.

Thanks