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Old 08-15-2015, 10:37 AM   #21
behnam92
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Default Re: Siemens 840D PCU50 Industrial Computer

can you help me identify the component that i marked in the attachment?
i thought it's cap and i bought smd cap with 157 marking on it but it isnt work properly .

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Last edited by Per Hansson; 03-09-2019 at 05:11 AM.. Reason: Offsite image uploaded
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Old 08-15-2015, 10:45 AM   #22
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Default Re: Siemens 840D PCU50 Industrial Computer

probably a diode, compare it to one of the others.
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Old 08-15-2015, 11:39 AM   #23
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Default Re: Siemens 840D PCU50 Industrial Computer

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Originally Posted by stj View Post
probably a diode, compare it to one of the others.
i compared it to the other ones , it doesnt act like a diode when i test it with multimeter it act more like a cap, i mean in diode testing mode i hear only small beep and then nothing in both ways ,
the marking on it is something like "150 j " .

Last edited by behnam92; 08-15-2015 at 11:46 AM..
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Old 08-15-2015, 11:54 AM   #24
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Default Re: Siemens 840D PCU50 Industrial Computer

well "157" would be 150uf - do you have a cap meter?
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Old 08-15-2015, 12:12 PM   #25
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Default Re: Siemens 840D PCU50 Industrial Computer

no i dont have one , but as i said i about 150uf caps but with different voltage rating(16v) and it didnt work , when i put it's own cap i have 3.3v output but when i use the one that i bought the voltage gets to 1.3 and it's not stable ,do you think the difference in the voltage rating could cause this problem?
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Old 08-15-2015, 02:03 PM   #26
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Default Re: Siemens 840D PCU50 Industrial Computer

no.
if the original gives 3.3v then isnt that correct?

where does the input to this "part" come from?
if it's the transformer then it is a diode - probably a fast or schottky type.
if that is the case then your cap is passing current and would explain things - need someone like budm to chime in on this!
i'm a digital expert, not an analog guy!
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Old 08-15-2015, 03:53 PM   #27
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Default Re: Siemens 840D PCU50 Industrial Computer

Quote:
Originally Posted by stj View Post
no.
if the original gives 3.3v then isnt that correct?

where does the input to this "part" come from?
if it's the transformer then it is a diode - probably a fast or schottky type.
if that is the case then your cap is passing current and would explain things - need someone like budm to chime in on this!
i'm a digital expert, not an analog guy!

yeah it's correct but i run it with just one of those caps or diods the other one that i showed in that picture was short circuited so i had to desolder it and even if it is working with just one of those i had to find a replacement .
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Old 08-15-2015, 04:14 PM   #28
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Default Re: Siemens 840D PCU50 Industrial Computer

o.k.
you have a set of 3, and a set of 2.
so i assume the psu has 2 output voltages.
what are the output voltages and currents?
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Old 08-16-2015, 02:36 PM   #29
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Default Re: Siemens 840D PCU50 Industrial Computer

i think i found the problem about why my system isnt booting up , as i said before this power supply creates some kind of power good signal for starting up the system,i've showed this figure in the pic below that i crop from siemens manual.
so i realized when i connect my power supply to 24V input it make somethine like beep buzz sound and it's from trans and i checked my outputs with osilloscope and i saw a voltage ripple in sync with the buzzing sound on all the outputs ,so i think this ripple affecting this power good signal and cause my system not to boot up , any idea on how can fix i this ? please help me i dont have much time for repairing it .



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Old 08-16-2015, 03:48 PM   #30
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Default Re: Siemens 840D PCU50 Industrial Computer

so why does the input voltage fail?

also, the output that diode is related to, what voltage and current rating is it?
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Old 08-16-2015, 10:23 PM   #31
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Default Re: Siemens 840D PCU50 Industrial Computer

no i didnt mean that the input gets fail, i meant when i connect the power supply to 24V ,the siemens power supply act like that so i have ripple on its outputs ,

Last edited by behnam92; 08-16-2015 at 10:24 PM..
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Old 09-09-2015, 01:38 PM   #32
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Default Re: Siemens 840D PCU50 Industrial Computer

Did you resolve your issue. I've got a similar issue, PC won't power on. Not sure if its the power supply or MB.

Could you let me know what your resolution was?
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Old 09-10-2015, 10:28 AM   #33
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Default Re: Siemens 840D PCU50 Industrial Computer

yeah i solved my problem recently ,
does your fans starts or your system is totally dead?
if the fans start and your system isnt booting up you have to check two things, first check the north bridge as other experts mentioned it in previous posts, you can try to apply pressure to it by your finger and then push the restart button to see if you have any output on your screen ,
if that's not the problem you have to check the signal good from the power supply by an osilloscope,
i fixed my problem by changing the ic on the power supply that was responsible for creating the power good signal ,

Last edited by behnam92; 09-10-2015 at 10:29 AM..
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Old 02-01-2016, 11:52 PM   #34
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Default Re: Siemens 840D PCU50 Industrial Computer

hello experts , hope it helps for my future problems
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Old 04-23-2019, 11:29 PM   #35
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Default Re: Siemens 840D PCU50 Industrial Computer

Hello,

I have two motherboards with that northbridge issue. Would anybody have some of this bracket A5E01040392 left, or knows a supplier? Siemens service is not able to supply it.

Any help is highly appriciated.

best regards,

Horst
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Old 04-24-2019, 12:46 PM   #36
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Default Re: Siemens 840D PCU50 Industrial Computer

I have one however it will not help you.
The board needs to be reballed, I've had one done successfully by forum member Th3_uN1Qu3.
That said this is a difficult board to reball because it uses black glue under the chipset.
I have also had success with eBay seller hicomp-gmbh, however the price is about 10 times higher.
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