logo elektroda
logo elektroda
X
logo elektroda
Advanced Search
logo elektroda

Sharp LC-55CFE6242E TV Issue: No Picture After Logo, Voltage Disappearance & Solution Options

baset 17154 11
ADVERTISEMENT
Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
Report a violation of the law
Reply | New topic
  • #1 17387143
    baset
    Level 17  
    Posts: 198
    Help: 31
    Rate: 98
    Hello.
    Sharp logo is shown when turned on, image fades out after a second. Voltage measurements on the t-tone at the time of switching on as described on the board, but after a while the AVDD voltage from the RT6929 system and VOFFE from the RT6930 system disappears. The remaining tensions remain normal all the time. What could be the cause of such a malfunction? T-con plate integrated with the LSC550HN02 matrix, so swapping is not an option. Maybe someone has datasheets for these scalers? Capacitors checked.
    Please, suggestions.
    Main board: T.MS6308.711
    Matrix: LSC550HN02
    Greetings.
  • ADVERTISEMENT
  • #2 17387391
    Indyczes
    Level 33  
    Posts: 3485
    Help: 185
    Rate: 268
    Do you have phonia, it responds normally to the remote control?
  • #3 17388114
    baset
    Level 17  
    Posts: 198
    Help: 31
    Rate: 98
    I tried to update with the software downloaded from Sharp, according to the instructions. The effect is that the LED has been blinking for several hours and nothing happens. No audio, no longer responding to the pilot. I didn't check the audio before the update, but it could be turned on and off from the remote control.
  • ADVERTISEMENT
  • #4 17388649
    lisek
    Service technician RTV  
    Posts: 39712
    Help: 6307
    Rate: 6802
    Sharp LC-55CFE6242E TV Issue: No Picture After Logo, Voltage Disappearance & Solution Options



    There are no datasheets available for these chips, so it's hard to say how they work with each other and the Controller on the T-con board. One is the QFN48 case / the other is QFN40

    From experience (with the described symptoms)> low voltages are present: 3.3 /1.8/1.2/12V
    - not with RT6930 -7.6 V / 11V
    - not with RT6929 17V and VGH / VGL / ...
    as I wrote in Link

    wine in:
    1.LVDS controler (?) 60%
    2. matrix


    ps
    LTF6280 (15Y_S40FF11MB7S4LV0.3 for matrix - LSY400HN01) Sony KDL-40RD453
    Attachments:
    • Tcon step by step RT6929.pdf (147.65 KB) You must be logged in to download this attachment.
  • #5 17389435
    baset
    Level 17  
    Posts: 198
    Help: 31
    Rate: 98
    Next week I will have my main board replaced. We will see if there will be changes.
  • ADVERTISEMENT
  • #6 17402314
    baset
    Level 17  
    Posts: 198
    Help: 31
    Rate: 98
    I replaced the main board, the symptoms remained the same. The diagnosis of my colleague Lisk is probably confirmed. Colleagues, does anyone repair such T-cones?
  • #7 18290783
    maly1108
    Level 11  
    Posts: 14
    Rate: 1
    Hello. I have the same t-con module in Sony. Identical symptoms, logo and black screen after a second.
    After disconnecting the connectors from the matrix, all voltages are correct. Second t-con module substituted and the same. Without the matrix, all the tensions are present, after soldering even one side, there is a half screen, half a logo and a black screen after a second.
    So what, it is known that the fault of the matrix.
    The matrix is complete, not damaged. The logo is perfect for a second.
    Anyone know what can cause this behavior of the matrix? Maybe she needs to be warmed up somehow ...

    I would like to add, gentlemen, do not be afraid of this t-con connector with the matrix. Homemade method, clean it well, liquid flux and normally it can be soldered.
    I have moved twice and everything works.
  • ADVERTISEMENT
  • #8 18602515
    audic5
    Level 12  
    Posts: 41
    Help: 1
    Rate: 52
    hello, it is 100% glass fault but I repaired two sons with kdl48w705
  • #9 18855895
    denyro
    Level 2  
    Posts: 2
    Rate: 12
    Hello guys!
    Sorry that I cannot speak polish.I got a sony kdl 48r555c with tcon board somehow the same,same ic´s rt6929 rt6930.Starting,sony logo comes and in a few seconds fade out.All voltages ok for few seconds,3.3,1.2,avdd,havdd,etc. then 0.Still backlight but no picture.After digging everywhere I cannot find a datasheet for rt6929.It seems that protection kicks in and stops all voltages.I resolved the issue by cutting MON_L , after trying with MON_R and no succes(I cutted first MON_R with no succes wich remained unsoldered! and then cutted also MON_L and voila!!!boom!!!) .Found a refference on youtube but I have no right to post the link.Hope that it will help someone.(Image is cortesy of those guys!)
    Sharp LC-55CFE6242E TV Issue: No Picture After Logo, Voltage Disappearance & Solution Options
  • #10 18855988
    lisek
    Service technician RTV  
    Posts: 39712
    Help: 6307
    Rate: 6802
    As for the model (kdl-48r555c) look at the page
    Link
    matrix eq. LSY480HN02-A01 or ?
    Quote:
    you have option Download the GN1S CHASSIS document in the archive (8.9 MB) *.zip

    Service Manual 126 pages /2015 г.
    Quote:
    KDL-32R500C, KDL-32R507C, KDL-40R510C, KDL-40R550C, KDL-40R555C, KDL-40R557C, KDL-48R510C, KDL-48R550C, KDL-48R555C, KDL-48R557C.

    Main look Link
    Quote:
    KDL-48R555C
    Board Number/ pcb: 1-894-094-22|173534122|A2066951B|A2066951C| A2066951D| A2066951A
    Manufacturer Part Number 1:Sony A-2066-952-B


    p.s
    RT6929- 1.2 V, 1.8 V, 3, 3V, 8.5 V, 17V
    RT6930- Vone

    Either damaged Matrix glass or ceramic capacitors on Matrix ears

    Sometimes it helped.
    Spoiler:
    Cut CKV1-4 and CKVB1-4 from the right side, connected them together from the glass side and through a 10K resistor to the body (without the resistor there was a horizontal strip).
  • #11 18885757
    denyro
    Level 2  
    Posts: 2
    Rate: 12
    Thank you very much!
  • #12 19113579
    Dusan23
    Level 1  
    Posts: 1
    Rate: 7
    Exactly mentioned problem with SHARP LC-55CFE6242E. The 17V and 8.5V voltages were lost immediately after switching on.
    Capacity OK. So I aborted MON_R. A vualaaa.
Reply | New topic
Report a violation of the law

Topic summary

✨ The discussion revolves around a malfunction in the Sharp LC-55CFE6242E TV, where the device displays the Sharp logo briefly before losing picture and voltage. Users report that after the logo appears, the AVDD voltage from the RT6929 and VOFFE from the RT6930 systems disappear, while other voltages remain stable. Suggestions include checking the T-con board and matrix connections, as well as potential issues with the LVDS controller or the matrix itself. Some users have successfully resolved similar issues by cutting the MON_L line, which appears to prevent voltage loss. The main board was replaced without resolving the issue, indicating a likely fault in the T-con or matrix. Users also express difficulty in finding datasheets for the RT6929 and RT6930 chips.
Generated by the language model.

FAQ

TL;DR: Sharp/Sony logo then black? 60% points to the LVDS controller; remaining to the panel. "There are no datasheets available for these chips." Diagnose RT6929/RT6930 rails; panel‑integrated T‑Con limits swaps. See practical workarounds below. [Elektroda, lisek, post #17388649]

Quick Facts

What causes the logo-then-black issue on Sharp LC-55CFE6242E?

Low rails (3.3/1.8/1.2/12 V) stay up, but panel rails drop. RT6929/RT6930 power down due to fault detection. Root causes skew toward LVDS controller (about 60%) or panel glass. "There are no datasheets available for these chips," which complicates diagnosis. Measure rails at power-on to confirm the shutdown. [Elektroda, lisek, post #17388649]

Which voltages should I check on RT6929/RT6930?

Check RT6929’s 1.2 V, 1.8 V, 3.3 V, 8.5 V, and 17 V outputs. Verify RT6930’s VONE/VOFFE generation. If these appear briefly then collapse, protection likely trips. Backlight may remain on while panel rails drop. Use a DMM with min/max capture to catch the dip. [Elektroda, lisek, post #18855988]

Why do AVDD and VOFFE drop after boot?

The T‑Con monitors panel load and trips protection when it detects a fault. This cuts AVDD/VOFFE and other panel rails after the logo. As one tech put it, "It seems that protection kicks in and stops all voltages." Backlight can stay lit, masking the shutdown. [Elektroda, denyro, post #18855895]

How can I tell if the panel or main board is at fault?

Disconnect both panel ribbons and power on. If all rails stay present, the panel is suspect. Connect only one side: a half‑screen logo that blacks out indicates a panel‑side fault. Swapping in another identical T‑Con showed the same behavior, reinforcing the panel diagnosis. [Elektroda, maly1108, post #18290783]

Does replacing the main board fix this Sharp issue?

Not in the reported case. The T.MS6308.711 main board was replaced and symptoms remained unchanged. That outcome pointed away from the main board and toward the panel/T‑Con glass assembly. Consider panel‑side diagnostics before ordering boards. [Elektroda, baset, post #17402314]

Can a firmware update fix it, or can it brick the TV?

A firmware attempt led to hours of LED blinking with no audio and no remote response. It did not recover the display. This is an edge case showing updates can leave the set unresponsive. Avoid firmware changes until hardware is verified. [Elektroda, baset, post #17388114]

How do I try the MON_L / MON_R isolation workaround?

This targets T‑Con protection feedback lines.
  1. Locate MON_L and MON_R on the panel‑to‑T‑Con connection.
  2. Isolate one monitor line and test for a stable image.
  3. If no change, restore it and isolate the other monitor line. One field report succeeded only after isolating MON_L. [Elektroda, denyro, post #18855895]

Did cutting MON_R actually fix a Sharp LC-55CFE6242E?

Yes. A user with the exact Sharp model had 17 V and 8.5 V drop at startup. After aborting MON_R, the image returned and panel rails stabilized. This confirms a monitor‑line driven protection trip on that unit. [Elektroda, Dusan23, post #19113579]

What other panel-side mods have helped in similar cases?

One advanced tweak: cut CKV1‑4 and CKVB1‑4 on the affected side, tie them together on the glass side, then add a 10 kΩ to chassis. This reduced artifacts and restored operation in a reported case. The author noted it only "sometimes" helped. [Elektroda, lisek, post #18855988]

Are datasheets available for RT6929/RT6930?

No public datasheets surfaced in the discussion. As stated by a contributor, "There are no datasheets available for these chips." Plan diagnostics by measuring labeled test points and comparing behavior between sides. [Elektroda, lisek, post #17388649]

Is it safe to re-solder the panel-to-T-Con connector?

A field tech reported success re-soldering that connector with liquid flux and careful cleaning. He did it twice and the assembly worked afterward. This can help if intermittent contact worsens protection trips. Use ESD precautions and fine tips. [Elektroda, maly1108, post #18290783]

Which other TVs show the same symptom pattern?

Sony KDL‑48R555C with RT6929/RT6930 showed an identical logo‑then‑black failure. All rails appeared for seconds, then collapsed, with backlight remaining. Cutting MON_L restored stable video on that unit. [Elektroda, denyro, post #18855895]

Is the panel glass always the culprit, and is repair possible?

One tech asserted, "it is 100% glass fault," yet he reported fixing two Sony KDL‑48W705 sets. Success depends on the defect and whether isolation or signal tweaks stabilize the panel. Results vary between units. [Elektroda, audic5, post #18602515]

What does a half-screen then blackout indicate during testing?

It points to a panel‑side fault. With one ribbon connected, you may see half a logo for a second, then black. When both ribbons are off, rails remain normal, reinforcing the panel diagnosis. Try side isolation and monitor‑line tests next. [Elektroda, maly1108, post #18290783]
Generated by the language model.
ADVERTISEMENT