My BFL SC Single 60 went out in a puff of smoke - what next? - page 3.

Cranky4u

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Quote from: peterepeat on November 22, 2013, 03:39:50 AM

Hi All,
I had my SC Single running nicely at 64 GH until a few days ago when it stopped hashing. I thought it may have been the power supply, and tried a brand new Corsair GS800 PSU. Anyhow, once connected, I heard a "crack" sound, no fans spun and a fair amount of smoke exited from near the middle of the PCB from underneath the smaller black heatsinks (not the ASICS). I doubt BFL will be any help, and with shipping to Australia taking so long+expensive - anyhow, has anyone else experienced this, and any suggestions on what I can try to fix it?
Cheers

I am an Electrical Engineer located in Bendigo, Victoria, Australia. I would be happy to take a look at your SC single to see if it can be bought back from the dead...PM me if ur interested

jojo69

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diamond-handed zealot

yup, VRM

question now is, did they fail because the ASIC failed and presented them with a bad load? or did they take anything else out when they went?

peterepeat

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I took the heatsink off which reveals 2 failed components I'm guessing Q2 and Q4 have failed. I couldnt see the identifier on these components, however one in the next row is 014NE2LI which I think is a power MOSFET.
The image of the heatsink shows the magic smoke escape locations.....

peterepeat

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Quote from: lightfoot on November 22, 2013, 08:06:49 PM

Thank you for posting those. I hadn't seen the newer boards fully loaded, that explains a lot.

In a nutshell, that section is where the 12 volt to 1 volt FETs are. There are two sets per side, for a total of four sets per big board (the little_single and jalapeno have two sets). Each set consists of three FETs which gate the "high" half of the 1 volt supply, and three FETs which gate the "low" half. At any moment, half the FETs are on. The capacitors then smooth out the flow and the voltage sensor on the 1 volt side feeds the computer back information on how long to keep the FETs on/off to maintain a smooth 1 volt.

When a FET fails due to overload or whatever it usually shorts. This puts the high and low lines on the 1 volt bus at the same time which shorts out one of the low FETs and the fuses blow in the power supply. Putting a new supply on it just fed straight into the dead short and let out the smoke in a "poof".

I've worked on things like this except they were 400a 300 volt IGBTs that would short on electric car transmissions. Same results with a *LOT* more smoke before the 350 amp main fuse would blow with a BOOM. :-)

Chris

Thanks for your input lightfoot - I will see if a local place can rework it next week. Maybe still some life left in it yet!

lightfoot

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I fix broken miners. And make holes in teeth :-)

Thank you for posting those. I hadn't seen the newer boards fully loaded, that explains a lot.

In a nutshell, that section is where the 12 volt to 1 volt FETs are. There are two sets per side, for a total of four sets per big board (the little_single and jalapeno have two sets). Each set consists of three FETs which gate the "high" half of the 1 volt supply, and three FETs which gate the "low" half. At any moment, half the FETs are on. The capacitors then smooth out the flow and the voltage sensor on the 1 volt side feeds the computer back information on how long to keep the FETs on/off to maintain a smooth 1 volt.

When a FET fails due to overload or whatever it usually shorts. This puts the high and low lines on the 1 volt bus at the same time which shorts out one of the low FETs and the fuses blow in the power supply. Putting a new supply on it just fed straight into the dead short and let out the smoke in a "poof".

I've worked on things like this except they were 400a 300 volt IGBTs that would short on electric car transmissions. Same results with a *LOT* more smoke before the 350 amp main fuse would blow with a BOOM. :-)

Chris

peterepeat

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Quote from: lightfoot on November 22, 2013, 07:16:09 PM

Hm, neat! Let me take a look at that...

Question: Can you take a picture of the whole half of the board? And the whole board front and back?

Edit: Fast thought: Based on where that is, I'd say it's one of the FET clusters (push/pull) for the 1 volt power rail for the board. The little sc/jalapeno has two of them, I wonder if the 60 gh SC has four or eight...

C

Thanks for having a look

heres the other pics

lightfoot

legendary

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I fix broken miners. And make holes in teeth :-)

Hm, neat! Let me take a look at that...

Question: Can you take a picture of the whole half of the board? And the whole board front and back?

Edit: Fast thought: Based on where that is, I'd say it's one of the FET clusters (push/pull) for the 1 volt power rail for the board. The little sc/jalapeno has two of them, I wonder if the 60 gh SC has four or eight...

C

peterepeat

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So I took the covers off to try and get a closer look. It appears what ever is underneath the small black heatsink failed.

peterepeat

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Quote from: runlinux on November 22, 2013, 10:28:23 AM

Have you tried giving them a call during normal business hours? They have answered my calls in the past. With this possibly being a warranty issue, I can see them trying to take care of it.

Thanks. I'll try to get hold of them

runlinux

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Have you tried giving them a call during normal business hours? They have answered my calls in the past. With this possibly being a warranty issue, I can see them trying to take care of it.

cowandtea

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Quote from: peterepeat on November 22, 2013, 07:05:32 AM

thanks - it wasnt a loud crack, and it was white smoke that had a really acrid odour. I thought I saw something bubbling as well (maybe it was electrolyte from a cap?) - anyhow, I emailed BFL when it happened, but havent heard a peep from them, so I guess I will try and get the heatsinks off and have a closer look tomorrow. Ill try and get some pics

good luck, you can try sell it if you want.. im sure there are people who buy broken asic...

peterepeat

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thanks - it wasnt a loud crack, and it was white smoke that had a really acrid odour. I thought I saw something bubbling as well (maybe it was electrolyte from a cap?) - anyhow, I emailed BFL when it happened, but havent heard a peep from them, so I guess I will try and get the heatsinks off and have a closer look tomorrow. Ill try and get some pics

DrG

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Been there, done that. I was sitting next to mine fortunately when it blew. Heard a pop (probably a cheap cap) and white smoke out the back as the fans spun down.

Good luck with RMA, took me 2 weeks just to get attention of somebody on the BFL forums.

There are a few people who are doing mods like lightfoot - maybe he would want the dead device for a fee.

demonmaestro

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Mining for the hell of it.

puff of smoke. was it white smoke? and how loud was the pop?

Matumaru

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I am not a electronic expert... but "crack" sounds like some bug exploded. Talking about the plausible cause... I would bet for static electricity while manipulating the machine.

I would remove (CAREFULLY) the heatsink and review the PCB, even with a magnifier in order to locate the exact place and component.

Or you can post a picture of the PCB both front and back and wait till someone take a look.

peterepeat

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Activity: 237

Merit: 100

Hi All,
I had my SC Single running nicely at 64 GH until a few days ago when it stopped hashing. I thought it may have been the power supply, and tried a brand new Corsair GS800 PSU. Anyhow, once connected, I heard a "crack" sound, no fans spun and a fair amount of smoke exited from near the middle of the PCB from underneath the smaller black heatsinks (not the ASICS). I doubt BFL will be any help, and with shipping to Australia taking so long+expensive - anyhow, has anyone else experienced this, and any suggestions on what I can try to fix it?
Cheers

Topic: My BFL SC Single 60 went out in a puff of smoke - what next? - page 3. (Read 5763 times)