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Dell Precision is a series of mobile and fixed computer workstations designed for professional consumers and CAD/Architecture/CG professionals, or as small-scale business servers.

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M7750 Display LCD Monitor appears dead

My M7750's LCD is out. However, the external HDMI and Display Port are working fine. I have replaced the internal LCD and Display cable that connects the motherboard to the LCD and Camera but, I still get no display on the LCD. That said, it would appear the NVIDIA board is working fine. The motherboard - as far as the LCD/Camera connector - appears to have no damage. When I installed the new LCD, does it need to be initialized within the EUFI BIOS? If so, how can I get into the BIOS when the external display does not show the bootup process on the external monitor? Again, the Operating System UI can be viewed on the external monitor only. I can not see the bootup process messages on the external; and I see nothing whatsoever on the internal LCD.

Update (09/28/2022)

Wow ... you are absolutely correct! I went into a dark room, and could see the logon screen when shining a light at an angle. Since there seems to be no shortage of what appear to be model numbers on the motherboard (I wouldn't know what area may contain what I need to identify), would the DELL Inventory list for the laptop help? Actually, I believe you could view the same by inputting the service Tag (12JM6G3), or the Express Service Code (2330662179) on DELL's Support page. In case you are not familiar, here is the link --> DELL Support Page . Since it doesn't appear I can upload a document, here is the text version of the inventory list -->

Component Part Number Description Quantity

817-BBBB : Custom Configuration W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

800-BBGH : BTO Standard Shipment (EL) 35CNK "INFO,INBOUND,AIRSHIP,XLGE" 1

780-BBFE : No RAID W9M89 "INFO,NO RAID,DIESEL" 1

658-BESN : Intel Sensor Solution H1R74 "INFO,INTEL,SW,ISS3P0,XLOB" 1

TJ0GC "SRV,SW,ISS5P4,RIALTO" 1

658-BEOK : Dell SupportAssist OS Recovery Tool 0GRTY "SRV,SW,EXCAL,WIN-CMPNT,CMRCL" 1

G08KV "SRV,SW,EXCAL-SOS/DDRE,BASE,CMR" 1

658-BDVK : Dell Power Manager 2PGXF "SRV,SW,DPM" 1

658-BCSB : No Microsoft Office License In cluded 7M1KY "SRV,SW,OFFICE,OPK" 1

HR8X9 "INFO,WINRE-ADDR,3,GB-PTN" 1

658-BBRB : Waves Maxx Audio M3C3H "INFO,RYLTY,WAVES-MAXX,AUD,PRO" 1

"658-BBMR : Dell Client System Update (Upd ates latest Dell Recommended B IOS, Drivers, Firmware and App s)" 9WV3G "INFO,.NET@V,35000,SP1" 1

CPWK1 "SRV,SW,DCU,APP,UWP" 1

GFGV0 "SRV,SW,DCU,APP" 1

650-AAJS : No Security Software 864KE "Information,PLACEHOLDER PIECE-PART" 1

640-BBSC : Dell Optimizer for Precision NRGNR "SRV,SW,APP,STD,DO" 1

R649X "INFO,RYLTY,RIVET,XPRSSCON" 1

640-BBLW : Dell(TM) Digital Delivery Cirr us Client C2N45 "INFO,SW,CRRS,UPDATE" 1

YR2T2 "SRV,SW,CRRS,MUI" 1

631-ACMV : System Driver for Mobile Preci sion 7750 P0R4D "SRV,DRVR,HID,INTEL,7X50" 1

RJWFV "SRV,DRVR,INTELTBT,7X50" 1

TVCJ7 "SRV,DRVR,LAN,TRINITY,TB16" 1

WXM2C "SRV,BIOS RECOVERY 2" 1

M7V88 "SRV,APP,WAVEMAXXAUDIO,7X50" 1

R1CGP "SRV,UTILITY,PPM,EPP,X10/X11" 1

81HXT "SRV,SW,MS,RMTDT" 1

137KG "SRV,DRVR,DPTF,7X50" 1

57154 "Service Charge,Software, Windows 98,Fully Integrated System Test" 1

19GP8 "SRV,DRVR,DCNTD,STDBY,WITH,UI" 1

57RPF "SRV,APP,IGFX,HSA,7X50" 1

83F5D "INFO,IRST,META-PTN,5M" 1

8F1PD "SRV,SW,SERIALIO,7X50" 1

9JTWW "SRV,DRVR,AUDIOTRINITYTB16,WD15" 1

C107G "SRV,DRVR,INTEL,IRST,7X50" 1

F2R68 "SRV,TBT,APP,7X50" 1

H9DKT "SRV,SW,MEM-CARD,MPWS,7X50" 1

HKHTT "SRV,DRVR,CHIPSET,MPWS,7X50" 1

HWGWM "SRV,DRVR,INTEL,LAN,7X50" 1

KFF2R "SRV,SW,AUD,MPWS,7X50" 1

NRTV4 "SRV,SW,INTL,IRST,APP,7X50" 1

NXY1G "SRV,SW,VID,INTEL,UMA,7X50" 1

631-ACMU : Intel vPro Technology Enabled 4WDG6 "INFO,RYLTY,VPRO/ME,RIALTO" 1

57Y07 "SRV,SW,ME14P0MB,RIALTO" 1

5M9J4 "SRV,APP,IMSS,RIALTO" 1

H738F "LBL,STNG,MGMT,AMT/VPRO,1" 1

VY54T "INFO,MGMT,INTEL,VPRO" 1

620-AALW : OS-Windows Media Not Included 864KE "Information,PLACEHOLDER PIECE-PART" 1

"619-ANUL : Windows 10 Pro English, French , Spanish" 0RR64 "SRV,SW,JUMPSTART,W10" 1

2H21J "SRV,SW,W10,XBOX,TOAST" 1

C3TDG "SRV,SW,PARTNER-PROMO-TOAST" 1

D6KX0 "INFO,WINDOWS,10" 1

GYTDF "SRV,SW,WIN10,RDX" 1

NGC17 "SRV,WINDOWS,REG,PWR" 1

X7V4Y "INFO,RYLTY,W10,DOLBY5.1,CODEC" 1

9NGMV "LBL,GML,MS,OS,WINDOWS" 1

GMFF7 "INFO,WIN,PRO" 1

8GM0D "DPK,W10P,HE" 1

025K3 "SRV,OS,WIN10,64,MUI,E/F/S" 1

0616F "INFO,BOOT,GPT,OVERRIDE" 1

C858J "INFO,XTRA-LANG@V,SPN" 1

D6KX0 "INFO,WINDOWS,10" 1

G174J "INFO,XTRA-LANG@V,ENG" 1

G424J "INFO,XTRA-LANG@V,FR" 1

HNX8N "INFO,IE@V,110000" 1

J471G "SRV,OS,MUI,INSTALLER" 1

KYWGW "INFO,.NET@V,46000" 1

PJ289 "INFO,VPEPR" 1

PY79K "INFO,.NET@V,50000" 1

T2673 "Service Charge,Operating System,Windows XP OCA-MARKER" 1

TM318 "INFO,SLP2,ENABLE,WINDOWS" 1

W728F "SRV,OS,IE,INSTALLER" 1

X0601 "INFO,BYPS,UPTN" 1

X278C "SRV,OS,DOTNET,INSTALLER" 1

XP9T9 "INFO,BOOT,CNTNR,GPT" 1

"583-BGIN : Internal Single Pointing Backl it Keyboard, US English with 1 0 Key Numeric Keypad" 713DM "KYBD,99,US,ENG,M19IXA-BS" 1

R9T05 "INFO,KYBD,BLIT,XLOB" 1

X903C "INFO,RYLTY,KYBD,BLIT,XLOB" 1

583-BGIK : Keyboard Lattice for 99 key an d 100 key keyboard XPPM7 "SHRD,KYBD,99,100,7X50" 1

570-AADK : No Mouse W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

556-BBCD : No Mobile Broadband Card 864KE "Information,PLACEHOLDER PIECE-PART" 1

555-BFTF : Intel(R) Wi-Fi 6 2x2 (Gig+) an d Bluetooth 5.2 JTYGJ "LBL,REG,WRLES,AX201,WW,BC" 1

XVV0P "CRD,WRLES,M.2,INTEL,AX201,NEW" 1

555-BFSH : Intel AX201 2x2 + Bluetooth 5. 1 Driver 083TW "SRV,DRVR,WRLES,M.2,AX201,RT" 1

H2RV9 "SRV,DRVR,WRLES,BT,AX201,RT" 1

KW6NT "SRV,HTML,WRLES,INTEL,AX201" 1

525-BBCL : SupportAssist 334CH "SRV,SW,APP,SACLIENT" 1

7CVVR "SRV,SW,APP,SACLIENT,W10S" 1

K53RM "INFO,RYLTY,SACLIENT" 1

492-BCXD : 240W E5 Power Adapter (EPEAT) 8YT3V "ADPT,AC,240W,LTON,7.4,EPT,E5" 1

"490-BFVC : Thermal pad for for Quadro RTX 4000,5000" FRNMW "ASSY,HTSNK,W/FAN,EQ3+5+G3R,775" 1

490-BFUY : NVIDIA Quadro RTX 5000 w/16GB GDDR6 0GF2K "CRD,GRPHC,NV,N19E-Q5,DGFF3" 1

9GK9G "SRV,SW,DRVR,NV,N19E-Q5,DGFF3" 1

C5MHH "SRV,SW,DRVR,NV,HSA APP" 1

DC2K8 "SRV,SW,DRVR,NV,WIN32UX" 1

NGRJG "Assembly,Connector,Board To Board,DGFF,7X30" 3

VYNYM "CBL,DGFF,PWR,EQ3/5,7750" 1

451-BCQE : 6 Cell 95Whr ExpressCharge Cap able Battery CR72X "BTRY,PRI,95WHR,6C,LITH,BYD" 1

450-AHDL : E5 C13 Power Cord 1M for North America M2PNC "CORD,PWR,125V,10A,1M,C13,E5,US" 1

430-XYGV : Resource Media not Included N4265 "INFO,NO-RESOURCE,CD" 1

401-AAGM : No Additional Hard Drive W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

400-BDWQ : M.2 1TB PCIe NVMe Class 40 Sol id State Drive 2HMFM "INFO,C DRIVE,PCIESSD" 1

3N94F "Solid State Drive,1TB,P34,80S3,Technical Sheet,XG6" 1

"391-BFHY : 17.3-inch, UHD, 3840 x 2160, 6 0 Hz, Anti-Glare, Non Touchscr een, 100% Adobe, 500 Nits, HDR 400, WVA" 44TRN "LCD,17.3UHD,HDR400,AUO" 1

1DP1N "INFO,RYLTY,PRRT,PRMR-CLR,6.0NB" 1

5NCC9 "SRV,SW,PREMIER,COLOR,6.0" 1

5TMH8 "INFO,SWSI,LCD,17.3,NON-TCH" 1

RJ77X "SRV,SW,WALLPAPER,7X50" 1

389-DVNR : Not EPEAT Registered W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

389-DUIK : Intel Core i9 Label for vPro NDY6H "LBL,INTEL,CI9,VPRO,10,SML" 1

389-DQBW : FCC Label RVD8N "LBL,REG,FCC,STATEMENT,9380" 1

389-BEYY : Regulatory Label included W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

389-BCGW : No UPC Label 2CVKK "INFO,NO,UPC,LBL" 1

387-BBDO : Not ENERGY STAR Qualified 864KE "Information,PLACEHOLDER PIECE-PART" 1

"379-BDWR : Intel Core Processor i9-10885H (8 Core, 16MB Cache, 2.40 GHz to 5.30 GHz, 45W,vPro)" W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

"370-AFGT : 64GB, 2X32GB,DDR4 2933Mhz Non- ECC Memory" P6FH5 "DIMM,32GB,3200,2R,16G,DDR4,NS" 2

354-BBCM : Bottom Cover with Smart Card D oor Opening VC3G3 "ASSY,DOOR,BTM,W/SC,7750" 1

346-BGIV : Palmrest with Smart Card only 185D2 "INFO,SC,CONTACT" 1

1XWFN "INFO,RYLTY,CV,KLC,PLTFRM" 1

46GV3 "SRV,DRVR,USH,7X50" 1

56XFV "ASSY,PLMRST,SC ONLY,7750" 1

NJKF4 "INFO,RYLTY,BRCM,CV3,SC" 1

WCRND "INFO,MDIAGS,USH FW FLASH" 1

340-CRET : Mix Model Packaging 2J81W "INFO,MIN-CONFIG,NB,BIZ,DAO" 1

43T1W "SHP MTL,UPAD,87X85X325,RIALT17" 1

DMW4K "SHP MTL,CSHN,MPP,T/B,RIALTO17" 2

FPWRT "SHP MTL,BAG,NBK,14.5X20,HDPE" 1

PPP52 "SHP MTL,BOX,MCF,551X94X344,BB" 1

TR2C9 "INFO,RYLTY,SI,TPM-MIDDLEWARE" 1

2J81W "INFO,MIN-CONFIG,NB,BIZ,DAO" 1

K9JDW "LBL,REG,COO,CHINA,CKS,7750" 1

22KHW "INFO,SHUTTLE,NB,BIZ,DAO" 1

HW105 "SHP MTL,BOX,ACC,17XX" 1

K9JDW "LBL,REG,COO,CHINA,CKS,7750" 1

TR2C9 "INFO,RYLTY,SI,TPM-MIDDLEWARE" 1

DMW4K "SHP MTL,CSHN,MPP,T/B,RIALTO17" 2

FPWRT "SHP MTL,BAG,NBK,14.5X20,HDPE" 1

1CVHX "SHP MTL,BOX,SHTL,466X94X341,BB" 1

22KHW "INFO,SHUTTLE,NB,BIZ,DAO" 1

Y364G "INFO,DIRSHP,CMPL,KUNSHAN" 1

340-CPYE : Quick Setup Guide for Mobile P recision 7750 YH3FH "PLCMT,QSG,PRECISION,7750,WW" 1

340-CKSZ : No AutoPilot W21JJ "INFO,GNRC,OEM,TRACKING,PN" 1

340-AGIK : SERI Guide (ENG/FR/Multi) WH67C "GDE,PROD,MUI,SERI,DAO" 1

"329-BFCF : Intel Core i9-10885H (8 Core, 16MB Cache, 2.40 GHz to 5.30 G Hz, 45W,vPro)" 7CCGK "INFO,TYPE C,AR/TR" 1

0K2XV "ASSY,BASE,7750" 1

68RR1 "PLT,THRM,PCH FOR CPU,7750" 1

6C9TK "PWA,PLN,I9-10885H,V,T,7750" 1

88N8F "BRKT,EDP CBL,7750" 1

GXR0R "ASSY,FRM,INNER FRM,7750" 1

J6M97 "CBL,BATTERY,7X50" 1

JY64N "Bracket,NGFF,Antenna,Connector,HOLD,7350" 1

PTVJW "BRKT,DC-IN,7X50" 1

XPX4V "CBL,I/O,PWR,DC-IN,7750" 1

"325-BDSS : IR Camera, Mic, Non-Touch beze l" 0XMGG "Assembly,Camera,1M,RGBR,Universal Serial Bus,2MIC,Form Factor" 1

25W60 "INFO,IR CMRA,FOR WBT CHECK" 1

4K81V "SRV,SW,OS,HELLO,IRLED,LIDCLOSE" 1

FTDDV "BZL,LCD,F/UHD,IR,CMR+MC,7750" 1

"320-BDUB : UHD Panel Cover, Non-Touch" 37YVY "CVR,HNG CAP,LOGUP,7750" 1

K5D5F "ASSY,CVR,UHD,IR,WL,7750" 1

210-AVUS : Mobile Precision 7750 CTO BASE J8PH2 "INFO,CHAIN,CUSTODY" 1

8D007 "LBL,SVC TAG,20X6MM,R0.5,BLK,AQ" 1

N0K6G "INFO,SWSI,NB,STD,MPWS,7750" 1

4P9FX "INFO,HASH,BIOS" 1

H82C5 "INFO,HASH,ENABLE,VERIFY,RGD" 1

XPRGW "INFO,UEFI-CL3" 1

009-9961 : Total Includes Shipping and Ha ndling 9 "Information,Generic,Part Number" 1

Update (09/29/2022)

Hi Jayeff,

You sound like someone who either does this stuff for a living, or have extensive experience in fixing these types of problems. Let me ask this: Assuming the schematic gives me a clue where to find the connection point, are we talking about some kind of physical switch with perhaps and electrical wire, or is this more like some kind of IC that logically gates the On/Off backlit function? If the latter, I'd further assume it could also be a circuit board trace that could've been scratched or "opened". Again, with the latter situation, are we talking about some component level de-soldering of the motherboard, or possibly re-soldering the trace that is broken? If so, I don't think I'd be comfortable doing that. Although I'm educated in Electronics Engineering, I worked more at the macro level as far as PCs and servers are concerned. In other words, I'd swap-out a card, or pull a hard drive but, replacing bad ICs on a printed circuit board is beyond anything I've done. Sure, I know the theory but, in practice there are other considerations like heat, and potentially screwing something else up. But, I'll stop there and hopefully get a hint at exactly what we are talking about here as a potential fix. Worse case, you've helped me tremendously with identifying the cause. Heck, the old LCD may have never been bad. In which case, I've thrown that money out the window because, I don't think the vendor would take it back. I'd be more comfortable taking to a repair shop but, I'm not sure there are many folks that can do component level repairs either. In which case, I'd probably be looking at replacing the motherboard. In any case, hopefully you can give me some idea but, if not thank you for pointing me in the right direction.

Answer this question I have this problem too

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Hi,

Try shining a torch at an angle close to the laptop's screen and check if you can detect any images at all when the laptop is on and there should be a display i.e. toggle the display to be either laptop only or both external and laptop and not external only.

They will be very faint if they are there so trying this in a darkened room may help.

If you can detect images you have a LCD backlight power problem.

Since you have replaced the LCD screen it seems that the problem is on the motherboard.

With a lot of laptop's e.g. HP, Lenovo, Dell etc, they're designed so that there is always backlight power being supplied to the screen from the motherboard but it is turned on and off in the screen by a signal voltage being turned on or off on a backlight enable lead from the motherboard.

What is the make and model number of the motherboard (printed on motherboard)?

Knowing this will make it easier to hopefully find the schematics for the board to find out what's wrong.

Update (09/28/2022)

Hi,

I was hoping that there may have been something like Wistron??? or Compal LA- ??? printed somewhere on the board.

Dell doesn't make boards. Boards are made to order for it by specialist board manufacturers.

Unfortunately all the info you provided are Dell part numbers, not the board manufacturer's part numbers.

You could try this schematic and see. I couldn't find one for your exact model. Select the appropriate model i.e. Schematic diagrams > Dell > Precision > 7740 (I'm assuming this is an M7740)

The model number is very close to yours so hopefully the only difference would be minor. Unfortunately you have to buy it. Hopefully you have a DMM (digital multimeter) and can read schematics ;-)

Note: To upload images/documents etc to your QUESTION in ifixit, click on Options > Edit (to the right of your question) and then place the mouse cursor where you want to enter the text etc and then click on the envelop icon in the header bar at the top of the edit and follow the prompts.

Update (09/29/2022)

Hi,

Without seeing a schematic the following is only a guess as to what it might be.

a). Best case it that there is an onboard smd (surface mount device)fuse in the backlight supply and that it has blown. Fuses on the board are marked with an F designation. Maybe check for any fuses in the vicinity of the video cable connector on the board.However in saying this there's always a reason why a fuse blows so if you find one that has you have two problems - i). knowing its specifications and ii). finding out why it blew in the first place. That's where the schematics come in handy as it gives the specs or model number of all the components on the board. Also the wiring diagram etc.. It may well be that there was a problem in the original LCD panel that caused it to blow.

b). There is no fuse but there's an IC (usually a mosfet) that is in the supply path and it has failed, either due to component failure - rare but it does happen or again some other problem caused it to fail - LCD panel problem hopefully.

Looking at images of your board online it seems to have a protective cover over most of the board so it was difficult to see the board but if you're keen you may want to remove that cover (detaches somehow?) and check for any obvious component failures e.g. burnt out IC etc - you can't see a blown fuse unless it was a spectacular failure so you'll need a DMM (digital multimeter) to test them for continuity.

It may be that there are reputable, professional laptop repair services in your location that can fix it. Perhaps check if there are any who state that they handle Dell products (authorized repairer?) as they usually have access to the schematics and/or experience with what may have caused this to occur.

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Thank you for your help

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Mark Gilchrist will be eternally grateful.
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