Topic: Dragonmint T1 16TH/s hashrate goes down after boot up (Read 72 times)

Hello!

I apologize if this topic has been covered previously, I have looked everywhere but I couldn't find something related to my problem.

I recently bought a second hand Dragonmint T1 16TH/s miner. It worked fine for 1 day then the problems began.

After boot up, the hashboards work at max hashrate, as shown in the picture: https://imgur.com/a/v3pTXh9  but that's only for 1-2 mins.
Then the fun part happens.

If all the hashboards are connected or recognized by the control board (meaning they have that red light on), it starts strong, at a 16-18TH then one board dies slowly: https://imgur.com/a/jwjgGa5  it goes from 4Th, to 3Th then all the way to 0.1TH (as you can see, this is just 1 minute later). But it would continue to work fine at 10-11TH/s, only 2 boards hashing properly.

Now the funny thing is, there was a power outage, no electricity for 5 mins, and now only 2 boards are seen from the start by the control board. And the process explained above happens again, after 2-3 minutes, one of the boards starts going down to 0.5TH/s.

I want to mention that these are different hashing boards. The middle one is not being seen by the control board and one of the remaining ones (chain 2) starts dropping in hashing rate, till it gets to 5-7 TH/s: https://imgur.com/a/KgGT0DS

That one time when all the boards had the red light, the latest firmware was used 15th May 2018, 060842. But I think it was by pure luck because previously the same firmware was on it but still only 2 hashboards were shown.
I tried an older firmware, still 2 boards, then got back to the latest one, and all 3 were shown.

I have tried everything:
     1)older firmwares (some of them didnt show anything, others still only 2 boards. I tried only Dragonmint T1 firmwares, I did not try Braiis OS, mostly because I dont have a SD Card slot and I don't feel that confident doing that)
     2)changing the pin connectors, from the power supply and from the control board
     3)changing the power supply
     4)rebooting it countless times
     5)trying different performance settings, the time when it picked up it was at Balanced, so I left it there
     6)Factory resets
     7)I unplugged it for 2 days, still nothing (I read someone had unplugged it for 3 days then it worked, perhaps I'll try 3 days then)
    
I don't think the boards are faulty, since they worked at full hashing rate for the first 1-2 minutes (back when all of them were visible). I hope they aren't the issue.

This is the load voltage for when the 3 boards were visible, but started going down, I hope it helps in a way:  https://imgur.com/a/1QjYUrK

The control board version is g19 and I only used Antpool, I haven't tried any other pool as I don't see how that would have any effect.


If anyone knows what might be the issue and possibly an easy fix, that would be great. Warranty is no longer an option since it had been opened up previously.

P.S.: I did clean it with compressed air and put in a warm room for any possible water vapors to evaporate before installing it, it's in a dust free room. The temps on the board were 73,75 and the one going down in hashrate was always around 63-65 degrees Celsius.