Topic: Simple S9 repair/overclock guide (Read 5912 times)

sub'ed / / / thx for the share OP

I will try the pencil trick on one of my S9's when I have some time. I'll have to find my good mechanical drawing pencils!
(It's a 600MhZ miner but in the last couple months must be set on 550 or there are X's scattered on two different boards.)
I will also check out the solder points you mentioned for fatigue or failure.

I'm assuming the pencil line will go left to right - as you are looking at the image above - and will only cover R10 within the oval.
Please correct me if I'm wrong.
Thanks for the information!!

This rocks. will try in the future. mark.

Do not remove the resistor.

Draw on it with a pencil. The pencil lead will lower the resistance and raise the output voltage. A small change in resistance can make a large change in voltage.

Have a bit of patience.

I've got 2 boards I can try this on. I'm pretty excited.

Edit: 9.15 on A board doesn't hash. any suggestions?

Save them, they might still be useful if everything goes fine with sidehack's S1 re-fit board (16nm Bitfury chips) project 

Yeah I had 16 AntMiner S1s at one time, sold off 8 and did the "pencil" trick with the other 8.  Man that was a rough two days!  Huge PITA to get the exact value needed, was really just trial and error!  The S1 was a bulletproof miner that would stay up for ages, after modding them about half of them would restart every couple days.  But hey, it dropped the power usage in half!

I still have those 8 modded S1s on a shelf in the garage.  I should probably toss em!

Ja. The resistor is about the size of a kernel of short-grained rice. When done, also be sure to carefully blow/brush off any graphite dust that might be around the area.

Just FYI for anyone who does this, those things are really tiny and you can't tell that from OP's super large images.  You are going to want a very sharp pencil.  I basically covered half of the resistor with graphite but it wound up being especially shiny along the edge since I was working without a magnifying glass and I am not exactly a surgeon.  But I took it apart and did it 3 times total to work up to a decent result.  Pretty pleased with how it is performing now.  Finally getting the advertised hashrate.

To OP:
Have you taken any resistance measurements of R10 before and after pencil tweak along with resulting output voltage to give us target values for the R10 mod?

edit: nvm... just looked back at OP and saw

As a Blast form the Past, here is the link to the original How to undervolt an s1 https://bitcointalksearch.org/topic/m.5838713 Dropped them from 1.19w/GHs to an amazing 0.89w/GHs Compare that to today's >7-8x lower efficiency. Woof!

Thought about doing it to the dozen s1's I had back then but -- each board had 4 regulators to tweak by hand and x2 per miner x12 miners.... just not worth my time to bother with.

Now with the s9 and 1 tweak per board and then only as-needed -- thass a while 'nother story. Thx for the info.

Thanks for this!  My batch 3 is running at stock freq without any X's for the first time ever.  The problematic hashboard still under-performs the other two slightly but it is getting higher hashrate then it ever has before.

It would be very uneasy to do it by rear fan hole, but it is possible.
Yes, it exactly helps hashboards which do not perform well at std frequency.

It was the s1 where the pencil mod was used.

'Lead' pencils are actually make of graphite and clay. Graphite makes the marks, amount of clay controls the hardness of the pencil. Point is, graphite is a form of carbon and is conductive.

Using a sharp #2 aka HB (soft) pencil to draw a line on the resistor essentially is putting a new resistor in parallel with R10 which lowers the resistance, in turn changing the Vref or Vfdbk applied to the regulator. Either way, it changes the regulators output voltage.

I remember some talk of a pencil mod back on one of the real early model antminers but I never did check it out so I am not sure what it is.  But let me see if I understand you, are you saying that drawing on the back of the R10 resistor with a pencil will increase the voltage of the chain and can help with hashboards that don't perform well at higher freq?  Does the graphite from the pencil conduct some small amount of charge across the resistor?  Also you are saying to be careful about it but having never done anything like this, what does a mark that would have a small effect even look like?

I am not sure where on the hashboard this is either, by any chance can you see this stuff without removing a fan?

Hello, it's been a while since my last hack. Now I am much more lazy, so no soldering tool will be used, but if you wish to, you are welcome.

This repair is intended for all batches of S9, except batch 17+ which I didn't tested yet. Main reason was that my S9 refused to work at full speed (550Mhz) and showed a lot of "xxx" chips. Lowering frequency helped to get all chips hashing well. My boards are out of warranty, so I suggest you to not do it while you have RMA period.

This guide also helps another issue with poorly soldered inductor and whole hash board disappearing from miner status.

Here is detailed hashboard with voltage converter:

http://www.pantin.cz/20161013.jpg

Firstly, look at your board and measure voltage across capacitor pins (mark A in the picture). It must be done while your miner is hashing (so at least 30s after booting). Voltage should be about 8.5-8.9V. If not, check carefully pins of inductor (mark B). If you see it is not fully soldered or you see some cracks, you will need to clean inductor wire and resolder it back.

And now, let's go to voltage adjusting hack based on LM27402 datasheet and tested my me:

measure resistor R10 resistance (mark C). Mine shows 4.86kOhm. Lowering this resistance increases voltage of whole chain, if you use pencil mod and draw on the top of R10, you will decrease its resistance. Be careful, small adjust will change voltage relatively high. Resistance of 4.5KOhm rise voltage to about 9.6V across chain.

If you want to use soldering tools, you can unsolder R10 and solder here serially connected 3.7kOhm resistor with 2.2kOhm multiturn potentiometer. This will allow you both over/underclock.

Pencil hack can be anytime reversed by cleaning R10.

My S9 which refused to work well at 550MHz, now works fine at 650MHz, but draws higher wattage. Highest voltage I tested was 10.5V, so it seems to be safe for decent OC.

This hack is at your own risk, I am not resposible for any damages you can do to your miner.