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Old 04-18-2018, 09:41 AM   #1
bootlegger17
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Default Ms7817 (msi h81m-e34)

Hi,

I have a troublesome motherboard. It will not start. PSU I believe is OK, and have swapped for like PSU and system still fails to power up, leading me to believe its a motherboard fault.

No activity from power switch invokes the PSOK/PON line on the ATX.
If I short the ATX green line to GND (for PON), the CPU and PSU fan spin briefly, then stop. There is a constand 5VSB line from the PSU into mboard.

It is very difficult to trace anything on the mboard, but I have found what I think are two suspicious things;

1) the 3.3v lines on the ATX connecter on the mboard all seem to be grounded - the 5V and 12V lines are not - I assume this is incorrect.

2) I have found a SOP-8 chip that seems to have two grounds, one on pin 5 which is correct, and also on pin 7, which is supposed to be the VOut - I assume this is incorrect? This is close to the USB pin outs section.

I dont think the two can be tied together - a vout and 3.3 line in would compete, so is there something common that could link the two which could be grounding them?

Regards
Jason
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Old 04-18-2018, 04:59 PM   #2
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Default Re: Ms7817 (msi h81m-e34)

Having read a post of similair nature on about another board on this forum, i have removed the realtek network controller, but the same fault still exists.
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Old 04-19-2018, 02:49 AM   #3
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Default Re: Ms7817 (msi h81m-e34)

anybody know where i can maybe get hold of a schematic for this mboard.
I have searched google and found about three references so far, but all go off to foreign (vietnam/thailand/phillipennes) based websites which I can not understand, and I think they are subscription sites that you need to pay for releasing the files.
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Old 04-19-2018, 05:06 AM   #4
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Default Re: Ms7817 (msi h81m-e34)

Schematics attached (hope it's the right one).
Can you take a picture of the SOP-8 chip and its surroundings? What is its part number?
What is the actual resistance you measure between this Vout and ground, and between the 3.3V line and ground?
Attached Files
File Type: pdf ms-7817 v1.0.pdf (691.3 KB, 28 views)
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Old 04-19-2018, 07:41 AM   #5
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Default Re: Ms7817 (msi h81m-e34)

thanks for the schematics.
However seeing on the last page the PCB1, that is not my PCB
FYI its this one;https://www.bhphotovideo.com/c/produ...therboard.html

As for the SOP, its by the realtek, and I have removed it, and tested pins and the two are not grounded to each other when off the mboard so I dont believe the realtek or this sop8 were at fault. I cant recall the sop8 ID so would need to have a look at it again, but this doesnt seem important now
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Old 04-19-2018, 04:42 PM   #6
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Default Re: Ms7817 (msi h81m-e34)

The sop8 was a uP0104S pgp51w. It was pins 8 and 6 grounded not 7 and 5 as previously mentioned
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Old 07-24-2018, 11:41 AM   #7
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Default Re: Ms7817 (msi h81m-e34)

I have a H81M-E33 which is a MS-7871 ver 1.2 which won't start.

Installing a PCI-E post card, no 3.3vsb was present.

Quote:
Originally Posted by bootlegger17 View Post
The sop8 was a uP0104S pgp51w. It was pins 8 and 6 grounded not 7 and 5 as previously mentioned
If you look at p24 of the schematic you'll see pin 6 and 8 are grounded. You'll also note that it shows that U16 has 9 pins not 8 - pin 6 is listed twice.

On my board, tracing from the 10K resistor then pin 6 should be Vout.

My board is also missing EC22 (see attachment0 and the pads for this are shorted too.

Can't find a datasheet for up0104s.
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File Type: jpg msi_7187_v1_2.jpg (84.3 KB, 8 views)
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Old 07-24-2018, 11:48 AM   #8
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Default Re: Ms7817 (msi h81m-e34)

Quote:
Originally Posted by bootlegger17 View Post
tested pins and the two are not grounded to each other when off the mboard so I dont believe the realtek or this sop8 were at fault.
Missed that first time round.

Last edited by Per Hansson; 07-29-2018 at 07:40 AM..
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Old 07-25-2018, 09:52 AM   #9
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Default Re: Ms7817 (msi h81m-e34)

Quote:
Originally Posted by brutech View Post
U16 has 9 pins not 8 - pin 6 is listed twice..
Or 9 is the pad on the back
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Old 07-25-2018, 03:24 PM   #10
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Default Re: Ms7817 (msi h81m-e34)

If +3VSB is shorted it's usually the Ethernet controller.
Check if it's heating up.
Otherwise, inject voltage, and search for the component that's heating up.
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