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Black screen on Sinumerik 840D, PCU50, Win4.0NT - probably PCU50 mainboard is damaged

Created by: xavery at: 8/20/2009 12:14 PM (9 Replies)

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8/20/2009 12:14 PM	Rate (0)
xavery Posts: 3 Rating: (0)	Hello. During loading the system screen suddenly went black. No warnings, no errors - nothing butpower LEDwas still ON.I tried buttons, trackball - no luck. After restart situation is the same. I tried also service mode, windows without HMI, system check- no luck. I have replace hard drive with imageand situation is the same - black screen after about 30-60 s (random)from the powering on the PCU. All cables connections are OK. I noticed the tops of the capacitors on the main board are fat and they look like the electrolyt went out of the capacitor (yellow dry markings on the top). The PCU is about 3 years old and the machine was workin 24/7 for the last year. Have you ever had this kind of problems with PCU50? Have any of you tried repleacing the capacitors? Cheers, Xavery Attachment PCU50-capacitors.jpg (727 Downloads)
xavery Posts: 3 Rating: (0)
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8/20/2009 1:48 PM	Rate (0)
Gebhardt Karl Platinum Expert Joined: 7/16/2006 Last visit: 12/20/2022 Posts: 1502 Rating: (175)	Hi What are the LEDs on the MSTT are do ? Can you switsch to AUTO, JOG, REF-Modus ? If Yes, can you move the Axis ? If yes, take a light, make lighting into Monitor. Do you see the information off the "Monitor" If all yes --> backlight is defekt.
	Karl
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8/20/2009 5:53 PM	Rate (0)
xavery Posts: 3 Rating: (0)	Thanks for reply! "What are the LEDs on the MSTT are do ?" - they are not blinking, some of them like JOGare ON but I can't select or change the axis. "Can you switsch to AUTO, JOG, REF-Modus ?" - I can't I think the screenbacklight is OK. I have chenged BIOS setting to "max power saving" and started Windows without HMI. I've tried it before like 30 timesandi've hadblack screen but surprisingly it worked.When Windows stopped loading data i started HMI from desktop icon. Everything was working, machine was running.Because of power saving mode the screen was going into blank (black screen)but whenI've moved the track ballI could see normal HMI screen. Unfortunatellyafter about 4 hours suddenly monitor went black again, machine stoppedand the only thing I could dowas to shut it down. Next I had problem to start it again. Black screen just after blue WinNT loading screen or during SINUMERIK840D background screen (with jet engine turbine) or just after selecting "Win without HMI" from service menu -just like before. PCU is acting very strange and random.
xavery Posts: 3 Rating: (0)	Last edited by: xavery at: 8/20/2009 5:54 PM
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8/21/2009 5:29 AM	Rate (0)
Jason. Experienced Member Joined: 7/13/2008 Last visit: 11/10/2022 Posts: 106 Rating: (9)	Occasionally, machine builders take advantage of the Screen Darkening and Key Disable bits in the interface from the PLC to the HMI, this is why the system probably appears to boot normally, but then goes dark as soon as the HMI software starts to run up. If you could, while the screen is dark, take a look at the plc bit. DB19.DBX0.1 for screen darkening. or DB19.DBX0.0 for screen bright. Normally, you can do this from the HMI, but not this time. You will have to use step 7 on an external pc. Another interesing one in the same area is KEY DISABLE DB19.DBX0.2. Usually there is a button on the machine control panel, or some other handy place that can be pressed to re-enable the screen, but like turning off the screen, it is builder specific. Occasionally, I come across a machine that for unknown reasons, the plc program contains code to make the screen dark. As for not booting...do you see the bios screen? PCU50's don't break that often in my experience. Maybe you need a new one. It never hurts to buy a couple of spares to put on the shelf.

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8/21/2009 7:31 AM	Rate (0)
RAM81 Silver Member Joined: 3/3/2008 Last visit: 2/20/2023 Posts: 333 Rating: (51)	hi normally on the pcu50 there isa VGA port available, can you try to connect a external monitor and find whether you are getting the windows or HMI area. is you are able to get the screen then problem could be with the OP , if there is no display then we have check the hard drive or PCU 50. may be we if you have a ghost image try to reload and check. with regards ram

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8/28/2009 7:21 PM	Rate (0)
xavery Posts: 3 Rating: (0)	Thanks for reply! RAM81: I did all test you mentioned - no success. Jason: It's very interesting what you wrote - I have to check it. "As for not booting...do you see the bios screen?" - Yes, I could access BIOS without any problems PCU50 was replaced with new one due to Siemens specialists opinions. Machine is running but a few days after PCU50 exchange machine acted very strange again. HMI software (it's Liebherr Gear Hob)started but there was no data for text messages and descriptions on the screenlike ablank form. After closer look into the problemsome of the files were missing. After loading those files everthing is running up to this day. Like I wrote before, HD was replaced, image was put (image 100% OK), PCU50 was replaced - everything should be OK.. I'm wondering what happens next.
xavery Posts: 3 Rating: (0)
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9/10/2009 11:44 AM	Rate (0)
ildus Posts: 1 Rating: (0)	Hi As I remember there must be 13 capacitors on the main board of the PCU-50, so change them all to have your PCU workable
ildus Posts: 1 Rating: (0)
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9/17/2009 7:52 AM	Rate (0)
CNCX Posts: 9 Rating: (0)	I agree with Ildus. You have to replace all the capacitors. That's the reason why your screen is blanking the screen the capacitor can not store voltage anymore.
CNCX Posts: 9 Rating: (0)
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3/23/2018 4:33 PM	Rate (0)
orrsti Posts: 1 Rating: (0)	Thanks. This was useful even more than eight years later. I replaced 12 capasitors in the PCU for a Poreba machine today with the same symptopms. Stig Orre Attachment 20180323_142854.jpg (426 Downloads)
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2/19/2020 10:59 PM	Rate (0)
Mtoolgrind Posts: 1 Rating: (0)	I am having a similar issue where the screen "turns off" and the machine shuts down. When it first happened, the only way to get it back on was to cycle the main power switch. Then one time I just happened to unplug and plug back in the power to the MPI interface board and the green start button on the front panel started blinking. I was able to hit this button and the machine came back on. What I realized is the machine wasn't actually shutting off, but going into power saving mode or sleep mode. (I can make the exact thing happen by hitting the red "power" button on the front panel) The only difference is, that if I put the machine to sleep with the red button, I can then "wake" it with the blinking green button. If the machine goes to "sleep" randomly (as it was doing), the green button won't wake it, and I have to cycle the power on the back of the MPI interface board. After talking with the tech at Siemens, I have ordered a new MPI board to see if that fixes it.
Mtoolgrind Posts: 1 Rating: (0)
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