It's just so dissappointing, we tried a lot and got nowhere. Hitting a brick wall every step of the way..
In any case, I'm really grateful that you took the time to help out. Thanks a bunch mate
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Anzezaf
Member
Last Activity: 12-13-2021, 03:37 PM
Joined: 03-18-2016
Location: Ljubljana
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Re: Sapphire HD 7870 possible short
It's just so dissappointing, we tried a lot and got nowhere. Hitting a brick wall every step of the way..
In any case, I'm really grateful that you took the time to help out. Thanks a bunch mate...
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Re: Sapphire HD 7870 possible short
TBH I'm quite fed up with these GPUs, plus i dont have such a mobo. If any other kind of possible solution crosses your mind, please say so - if not, i will just sell it and see how much i can get....Leave a comment:
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Re: Sapphire HD 7870 possible short
Hey, sorry for the late reply. Did some googling and some guys are saying that on a MSI r9 290x, the LED shows the "powerstate?" and/or something called "ULPS".
Another guy from that same thread is saying
"I have 2 290's from MSI and saw the same green light. The light comes on because of AMD's "ZeroCore" technology. When the GPU isnt being used/outputting to a display it effectively turns off, the fan stops etc. The light must be to show that the GPU is still actually on and working...Leave a comment:
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Re: Sapphire HD 7870 possible short
Eh, I measured at the points you wanted, but there isnt any voltage on any of them, all 0V. May be due to the fact that i ran it on a only 420W PSU (and as a result, the PSU didnt supply the GPU because its too weak) but i doubt it - consumption while not under load should be small. Also, the fan of the cooler didnt spin up, but there is an LED on the board thats shining.
Goddamn, was I pissed when trying to solder anything on the mentioned spots, couldnt get a nice solid joint no matter how I tried. I think I must have spent at...Leave a comment:
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Re: Sapphire HD 7870 possible short
Right, I now checked all polymer caps on the first GPU, and the only ones showing a short were those 4 blue lined ones near the RAM chokes. Removed them, but they all turned up normal.Leave a comment:
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Re: Sapphire HD 7870 possible short
Will remove them and report back.
I didn't measure it for more than a few seconds, so it could be some caps filling up, but i checked again this morning (surely any caps would empty in ~12 hours)and the multimeter again showed an open circuit.. A mystery indeed
Here's the pic of the area mentioned.
Notice there is only one differential trace to be seen,and it leads to/under a RAM IC/chip. Everything else is routed through vias on the three big pads. It might...Last edited by Anzezaf; 04-17-2016, 05:57 AM.Leave a comment:
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Re: Sapphire HD 7870 possible short
Nope, removed the buck controllers, and resistances are the same.
Looks like i'm gonna have to chuck in the trash, don't really know what else could be causing the problem? I think we pretty much isolated the whole power section of the card, and the short is still there.
EDIT: Say, momaka, are you willing to have a look at the 2nd card? Looks like the first one is a goner, but there might still be a chance for this one. Comparing to the first one, I think this one is a bit more promising - some higher resistances measured....Last edited by Anzezaf; 04-16-2016, 01:26 PM.Leave a comment:
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Re: Sapphire HD 7870 possible short
Hey guys, i'm back. Finally got the hot air gun and went to work. Removed all the tantalum caps which were all ok - showing open circuits. I then removed both the RAM and GPU lower fets and they were also fine, every single one of them.
Next, I measured the following resistances:
-GPU lower fet's source to GND ~0.6ohm
-GPU lower fet's drain to GND ~0.9ohm
-RAM lower fet's source to GND ~0.6ohm
-RAM lower fet's drain to GND ~1.5ohm
It really bummed me out when I saw every fet is OK. Is there anything...
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Re: Sapphire HD 7870 possible short
I tried removing the 470 capacitors with a 30W iron on one side and a 100W on the other and they wouldn't budge. The board is incredibly efficient at cooling so I'm waiting for a friend to lend me some kind of hot air fan, I might be able to something with that. I should get it this week and hopefully I will be able to report back during the weekend
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Re: Sapphire HD 7870 possible short
Right, thanks for taking the time again.
Now, I don't have an SMD hot air soldering station, and it's quite expensive to buy one, so I'm wondering if it's safe to desolder the FETs with a normal iron applied to the case? Since there's no plastic to be seen, I think this could actually be possible. But, on the other hand though, there might be plastic filler inside the case itself, which could present a problem. (By plastic i mean the bakelite or some kind of similar material that IC's are encased in)
...Leave a comment:
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Re: Sapphire HD 7870 possible short
Small bump. Having nothing better to do, I "mapped" some IC's on the board. Figured it might help.
[LIST=1][*]78M05G 500mA voltage regulator[*]PL25LD010 SPI flash[*]SL1601 clock generator[*]CHiL CHL8228G multi phase buck controller[*]Bank of CHL8510 gate drivers[*]PL25LD010 SPI flash again[*]MC74VHCT125A quad bus buffer[*]pair of CHL8510 gate drivers[*]CHiL CHL8212 Multi-Phase Buck Controller [/LIST]- Re: Sapphire HD 7870 possible short
Small bump. Having nothing better to do, I "mapped" some IC's on the
Last edited by Anzezaf; 03-30-2016, 10:57 AM.Leave a comment:
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Re: Sapphire HD 7870 possible short
....Leave a comment:
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Re: Sapphire HD 7870 possible short
I also wanted to check the buck/phase controller (the large IC on the far right side of the card, near the fan headers) for any shorts, but I cannot make any sense of the pinout in the datasheet - can't find any grounds. The IC is CHL8228G and here's the datasheet. [url]https://cdn.badcaps-static.com/pdfs/e7b4b4be233b893ab8abc917738a7af4.pdf[/url]Re: Sapphire HD 7870 possible short<..., but I cannotLeave a comment:
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Re: Sapphire HD 7870 possible short
Hey guys, a quick bump.
I really really dont want to be ungrateful for all the advice already given, but I am kinda in a hurry to get this sorted ASAP, if even possible.Leave a comment:
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Re: Sapphire HD 7870 possible short
Thanks to everyone for the input and correcting me on the power supplies
@momaka
The fans in the computers spin normally.
I now measured the GPU and RAM voltages but i get nothing. 0 volts on RAM inductors, and weirdly consistent 0.03V on GPU inductors... The GPU itself does get hot though, pretty fast at that. How the hell is this possible, 0V yet the GPU is getting power..
It's a slim chance... but could the 0 volts be due to the fact that the card doesn't boot properly in the few seconds i had...Last edited by Anzezaf; 03-21-2016, 05:54 PM.Leave a comment:
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Re: Sapphire HD 7870 possible short
Hey, my first time here but i already see there are plenty of guys here that know what they're talking about. Anyhoo, I'm reviving this thread because i seem to have a similar problem. I have an R9 280X gpu that fell victim to what i think was a short circuit on the external PCIe power connectors. Here are the pictures of the card.
[url]http://imgur.com/a/t94Da[/url]
I tried the card in several computers and none of them boot up (one of the PCs had a loudspeaker and beeped a GPU error, so it's certain that the card is faulty)....Leave a comment:
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