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1  Bitcoin / Mining support / Fixing Dragonmint T1 miners: Thoughts and observations on: February 14, 2020, 12:36:29 AM
So I've had a few requests to fix broken Dragonmint miners. These are.... interesting units and the boards seem to fail a fair bit. As usual there is little to no documentation on the hardware itself, so in order to fix it you kind of have to reverse-engineer the thing. What fun....

First up is to take a look at non-working boards and see what they do. Since we can't talk to them on the spi bus we have to use other tools. In my case I like to start with a watts up power meter on the supply (to monitor how much the board is pulling and when) and an infrared camera to see exactly what is warming up/pulling heat/shorted on the board.

To a fault, the first three bad boards exhibit the same symptoms: They start out pulling pretty much no current, then pull about 60-120 watts of current for a few seconds, then it drops back to zero. This correlates with the logs from the miner trying to initialize the bus and get it going. On a working board it will go to 120, then 250, then whatever the watts the board is tuned for (in the lowest power setting case around 355 watts).

Second was to take IR pictures of the bad boards. And I spotted something pretty quickly: When the board started up one chip on the control circuit got very hot, then the heat went away once the power draw dropped to zero. Like clockwork. I focused in on the chip and found it's an 8 pin SOIC chip with a part number of KBA6F1806
on two of the boards and KBA6F1752 on the third. Pin 8 goes to ground, two pins go to an RC circuit, and one pin goes to the crystal oscillator.

It doesn't seem to be a FET driver, I'm wondering if it is a scratchpad memory for the main processor circuit. However I haven't found anyhting on it, anyone know what it is? If it's overheating then we may have an answer to the problem: That chip goes bad and the board is dead.

Currently I am cooling down a working board in the fridge to see if that chip warms up when the board is first communicated with. On a hashing board it does not show any sign of excessive heat but at that point the copper planes in the board are conducting heat pretty uniformly.

Thoughts on what that chip might be? One way to test my theory is to remove the chip from the good board and swap one of the suspect chips in. Got to be something :-)

another board
2  Bitcoin / Mining support / Hacking Bitmain Antminers (S7 & S9) because man a lot of these break...... on: December 27, 2017, 01:51:41 AM
So although I have steered clear of Bitmain miners in the past I figured enough people have been having issues with these miners and it's time to figure out what the heck is going wrong with them. So I'm starting yet another thread on hacking these things to either fix them or at least figure out why they blow up.

This will be under my normal license: Information should be free, skills should be paid for. Therefore as I find out stuff about these miners I'll put it here. If anyone else has thoughts or technical specs please feel free to share them.

I'd rather this not turn into a general discussion on the merits of Bitmain, Bitcoin Crash, or anything else like that, will try to keep it to the technical bits.

The second post will be a FAQ of most interesting stuff, and the third post will be reserved for other administrivia.

On with the show. Or as I like to say:

"What's the worst that could happen?"
3  Bitcoin / Mining support / Hacking miners, general info on troubleshooting. on: November 07, 2017, 03:26:09 AM
Ok, after answering the same question a bunch of times about Avalon things, NotFuzzyWarm pointed out something:

There really isn't a good thread for general information about miners.

Common information like why do they run, why do they shoot flames out the front from time to time, and of course why did the power plugs melt on them. Or how about tips on making them run well, what to do with heat (send it out a window....), and common simple troubleshooting techniques that can get people mining again?

Since I fix these things and figure stuff out the old fashioned way (probes and a general understanding) I thought I would use this thread to post some of my findings and let others contribute to general knowledge. It will take me a few days to get stuff written down, so be patient and check back from time to time. If it gets good enough maybe it can be locked to the top page.

Anyway, on with the show. I'll update this thread regularly with new information as I learn it, hopefully this will help people.
4  Bitcoin / Hardware / Lightfoot at Defcon 25, anyone want to come to a talk? on: July 28, 2017, 06:25:42 AM
Well I'm here at Defcon taking a bit of a break. You can find me pretty easily, I have a mining board instead of a badge around my neck. Feel free to say hi, already have met a few people here.

I'm going to go down to the Hacking village on Friday and see if they would like me to do a talk. I've brought the bag of tricks with me, so I could do a presentation on how to spot and fix some common issues on bitcoin mining gear and how to figure out what's what. If so I'll probably do it Saturday, will check.

Anyone else here and want to hit a bitcoin machine for the hell of it?

5  Bitcoin / Meetups / Anyone want to meet up at DefCon? on: July 14, 2017, 03:55:14 AM
So it's time for me to drag myself out to Defcon and Bsides again. Partially to get out to Vegas, test the bitcoin machines, get drunk, and possibly teach some sessions over at the happy hardware hacking hall. Maybe I'll bring some toolz, will definitely be looking to improve my safe cracking skills.

Anyone want to meet up/grab a beer/have your miners fixed in person/etc? Should be around the 27-29th of July.

6  Bitcoin / Hardware / Fixing Avalon and other miners because people keep sending them in... :-) on: June 06, 2017, 02:24:49 AM
Hello all!

I'm Lightfoot, and this is my thread for fixing general miner problems with bitcoin miners.

I started with Jalapenos, then went to fixing Monarchs, Neptunes, have been enjoying a good run with KNC Titans and now I'm branching out into fixing other types of miners. Mainly because people have them, they need fixing, and I enjoy working for bitcoins and litecoins. Go figure.

Anyway, this thread will be similar to my other threads where I fix KNC stuff and the like. Same rules apply: I get stuff to fix, I post what I do, what I learn, and charge for my time and expertise to repair. The classic information is free, experience is rewarded thing.

As for myself, I have been fixing miners for about 4 years now and have gotten pretty good at it. Truth be told there are only so many ways to build a miner, and I've been able to troubleshoot a lot of problems without the help of things like schematics, vendor help, and the like. Not that I would refuse it, if a vendor wanted me to help I would be happy to, I just would write what works so other people can fix things too.

I have air tools, SMD rework tools and the almighty board pre-heater. Seriously if you want to fix PC board get a good pre-heater even if you're using a soldering iron. They warm the board up, allow the solder to properly flow, facilitate taking off components with ease, and most importantly allow you to reduce the temps on your iron which keeps the board from getting burned/traces lifted. There's no feeling quite like opening someone's miner to find that someone else took a blowtorch to the inside.

Anyway, on with the thread. Unlike my ones about KNC Titans and Neptunes, this will cover general bitcoin miners. If you have a question feel free to post. We'll start with an Avalon A6 which came in with toasted power plugs....

Lightfoot Labs
7  Alternate cryptocurrencies / Mining (Altcoins) / Hacking L3 Antminers because someone asked me to. on: February 03, 2017, 01:50:51 AM
Ok, new project: In addition to the Titans and GPUs, I was asked to take a look at an Antminer L3 that  appears to be dead on arrival. As is my custom I'll post my findings here and hopefully we will find a way to get them working without having to send them to China or wherever.

I'll post summaries of findings here, technical details below. Feel free to contribute thoughts, pictures, or comments.

8  Alternate cryptocurrencies / Mining (Altcoins) / Hacking GPU cards back into operation because I need something to do.... on: January 11, 2017, 02:38:36 AM
So I've been fixing Titans, Neptunes, Monarchs, Singles, Avalons, and a whole bunch of mining technologies over the years, but for some reason never really fiddled around much with GPU cards. They blow up too, and I see them on sale at Ebay all the time. I need a challenge, so I thought I would start a thread on my observations in fixing them if possible, developing techniques that can work, and figuring out how to tell one that can be fixed from a brick.

As normal, I will post my thoughts below and see what I can come up with. First up I need to find some dead cards to practice on....

Background: Years of doing SMD repair on electric car power controllers (400v/500a) as well as miners (.6 volts, 1000 amps) and other small things. I prefer to use hot air rework tools, and I like to use pre-heat to keep from roasting components. I don't use the toaster to repair boards. :-)

Let's see where this goes.
9  Economy / Services / Bitcoin and Litecoin miner repair services (for BTC/LTC) on: January 04, 2017, 07:31:06 PM
I realized after fixing these things for a few years that I should post something in this section, so here we go:

I've been fixing ASIC miners for a few years now on this forum and documenting my results in a number of threads. Currently I'm servicing KNC Titan/Neptune series miners, but I've also worked on Avalon, BFL, and a few other types of devices. Reflow/rework/fixing boards that caught fire, that sort of thing.

My main goal has been to help the bit/altcoin community to keep mining like hell, so I try to do reasonable prices for bringing things back to life.

If you need assistance, feel free to drop me a PM or post in this topic.

10  Alternate cryptocurrencies / Mining (Altcoins) / Hacking KNC Titan / Jupiter / Neptune miners back to life. Why not? on: December 10, 2015, 11:00:10 PM
Ok. So someone asked me if I could fix some broken Neptune miner boards that would not hash, partially hash, and so forth. I said why not and sure enough a box of junk appeared.

What this thread will be is a technical discussion on what is wrong with these miners, and how someone with medium SMD rework tools might be able to get them working again. I'll cover the basic boards, controller boards (got two of those too in unknown condition) and the like and see how far I get.

Second post will be pointers to things I have found, as trying to read through a hundred pages of KNC threads is a bit complex.

What's the worst that can happen?

(Edit: Fixed to Titans first since we're now in the ALTCOIN section)
11  Economy / Goods / Want to buy Aeron ass cradle on: September 30, 2014, 01:46:31 AM
So where can I buy an Aeron chair for Bitcoin? I need a top of the line ass cradle.

12  Economy / Services / If your BFL Monarch miner fails, I will service and fix it, gratis. on: September 24, 2014, 02:12:27 AM
Well, with BFL under this cloud of stupidity, I realized that there's nowhere to send RMAs. Given that I own a Monarch (bought on Ebay for 2btc) and have taken it apart a fair bit, I'll make this offer to the community:

If your Monarch shuts down, blows up, or ceases to hash post here and let me know. I'll send you my address, and I'll fix the thing for you. Right now what I can see failing is the FETs, which I can fix as I have pulled a lot of them on the 65mn gear.

I have the tools, I have the cred, and I want to help the people who have these units. Price is free or whatever you want to pay me for this. I'd rather help than scalp.

Post wherever, this is an open offer. Let's pull together and mine like hell.

13  Bitcoin / Hardware / Hacking BFL Monarchs and servicing them while times are weird. on: August 27, 2014, 11:27:20 PM
Ok, it looks like BFL's Monarch board is shipping, pictures are starting to pop up, and I'm looking at the one on Ebay and going "MMMMM It would be FUN to FIDDLE WITH IT". Yep. It looks very cool....

Edit: I just bought one on Ebay for $1k worth of Bitcoin. Yep, by Wednesday it will be MINE! BWAHAHAHAHAHAHAHAHA

Ahem. So I thought I would start a thread for people to post their pictures, thoughts, and the like. I really am not interested in whining posts, so I will attempt to moderate this thread specifically to technical discussions.

And in a "support the people who bought them and put my bitcoins where my mouth is" I've just sent 8 bitcents to an early owner so he can get a P3 meter and a temp sensor so we can see what they do and get some data.

Congrats to BFL for shipping, let's see what we have...

14  Bitcoin / Bitcoin Discussion / Prosletizing Vegas Prostitutes with Bitcoin on: August 06, 2014, 12:43:24 AM
Ok, so I'm here in Vegas, I've been walking the strip going to and from hotels, and I've been "talked to" by at least two young women wearing the tight jeans, cute, young, etc. While sweet and kind of flattering, no.

However I realized something: I chatted up someone on the plane flight over here and explained Bitcoin to him, he got it. Why not chat up the prostitutes and get them to start using Bitcoin for their transactions?

I mean Defcon is this weekend and there will be thousands of young hackers with bitcoin wallets that need lightening. What better way to help the hacker community and promote Bitcoin acceptance by explaining it to hookers?

How best can we do this? I'll talk to them; I talk to anyone with no problem, and I'd like to help as always.


15  Bitcoin / Hardware / Going to Defcon? I'm brinigng the happy hardware hacking bag..... on: August 04, 2014, 06:57:46 PM
Ok, since a few people are going to be there I'm going to bring my bag of hardware hacking tools to Defcon and setting up in the lobby or something. We can do demos, pull chips from 65nm miners, and chat/swap stories about how to make mining hardware faster.

Bring something to hack, and post a reply here if you want to attend. Then we can go out for booze and gambling or something.

Post here or in my meetup thread if you want to get together, and we'll arrange time/space.

16  Bitcoin / Meetups / I'll bring the hardware hacking tools to Defcon, let's meet and swap tips on: August 04, 2014, 06:56:43 PM
Ok, since a few people are going to be there I'm going to bring my bag of hardware hacking tools to Defcon and setting up in the lobby or something. We can do demos, pull chips from 65nm miners, and chat/swap stories about how to make mining hardware faster.

Bring something to hack, and post a reply here if you want to attend. Then we can go out for booze and gambling or something.

Post here if you want to get together, and we'll arrange time/space.

17  Bitcoin / Hardware / Defcon 22, will do a talk about hacking mining hardware for fun, fires, profit.. on: June 10, 2014, 01:33:51 PM
Good morning!

Well, Defcon22 is coming up soon in Vegas, and I thought I would host a talk about my experiences with hacking bitcoin miners to make them run faster/cooler/better. And meet people, it's always fun to meet people and talk about hacking things.

So I took my chatting and notes from the thread: Hacking BFL Jalapenos;topicseen, and the Hacking BFL singles thread, and turned it into a presentation called:

Hacking Bitcoin Miners for fun, flames, and profit.

Unfortunately the talking schedule is full, so they couldn't fit my talk in. Drat. However if there are people interested in hearing how to tweak I'd be more than happy to host a 1 hour discussion during the Con in the Con Suite, break room, etc to chat about Bitcoin.

I think it could be fun, and educational. If enough people sign up maybe we can take over a hotel or something. Hardware Hacking-Con!

So who is going to Defcon this year, and how shall we all meet up? Who can bring the beer for the bitcoins and whip up invites and logos for the get together?

I'll post a summary of my talk here in the next day or so. Also what's the best way to spread the word about this? It's a big community and I'd be interested in meeting you all.

See you in Vega$.

18  Bitcoin / Hardware / Rain and snow took out my miners.... on: April 16, 2014, 03:03:55 AM
Well, it was bound to happen. I have moved about 300gh of my mining power out to my solar powered shed to take some of the heat load off the house. Today we had massive rain and snow in MD, and in the afternoon I got a note that the shed miners were offline. Figured they tripped the GFCI.

Nope. Shed door had blown open and rain blew in. Got one of my Corsairs wet (had to be the 750), it's dead as a doornail. Not sure why. However when I moved a spare power supply in, two of the units didn't come up: My Chili and one of my 50gh Single boards.

The Chili is dead, barely starts the fans, no lights. The Single comes up but no USB. My guess is the power supply faulted and took out the FTDI chip somehow, which is odd since the PSU is grounded and everything is on GFCI's. Great, the 100gh of hashing and $80 power supply failed to protect the $5.00 GFCI socket.

Everything else is up and running again and I have latched the door. 32 degrees out now, I'm sure it will be in the 80's tomorrow. Gotta love climate change....
19  Other / CPU/GPU Bitcoin mining hardware / What is the worst motherboard I could buy for mining? on: February 14, 2014, 01:26:41 AM
Ok, in a moment of utter stupidity I bought a broken ATI Radeon 5770 card on Ebay. Yes, I know it's garbage and broken. Yes I'm bored so I will just fix it.

But I realize the only computer I have that might have a PCI/16 slot is a 2006 era Mac G5. And that's a bit... old... to compile anything on anymore.

So the question: What is the cheapest, most useless, most pointless board I can buy that I can plug into a Corsair and a cheap-ass IDE hard drive. Hell, I could probably find a 600mb ESDI drive in the junk pile. But the point is to run something simple, small, cheap, cheap, and did I mention cheap to plug this card into and get it running.

Because I just know my next step is going to be one of those spaghetti miners with 20 GPUs mining fucking DOGE 24*7 (*). So why not start at the utter bottom of the barrel.


* DOGE! TO DA MOON!!!!!!!!!!!! MORE HAZ COINZ!!!!!!!!!

20  Bitcoin / Mining / Hacking a BFL Single/25 to 48gh and beyond..... on: January 20, 2014, 06:13:54 PM
Ok, I've pretty much taken the Jalapenos to their max limit (32gh, with 6 added chips and a lot of cooling) so now it's time to take on the singles. Much bigger board, has possibilities, but also has some interesting limitations.

My goal is to bring a 25gh single up a bit power-wise, maybe to 48-50gh or so. The unit I will be working with here is a standard single/25 which was bought by me running at 23.5gh tops. Which was a bit slow. In checking it out I found the chips ran slow, and one of the chips was missing from BFGMiner's point of view.

Update: Added two sets of FETs, driver, capacitors, and 5 chips. Hashing very nicely at 48gh and temps of 72c with a speed reducing resistor on the output fan.

If you're curious about the other things I do, check out my jalapeno thread at:;topicseen

Here we go....
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