FAQ
TL;DR: For this Blaupunkt 32/1471‑GB no‑picture case, one LED on the backlight was dead; “one LED is off.” Replacing the LED strips restored the image. [Elektroda, stiff12, post #17118753]
Why it matters: If your 12 V and 5 V rails look fine but the screen is dark, check the LED backlight first.
Quick Facts
- Affected set: Blaupunkt 32/1471/GB‑5B‑HBKUP‑EW with TP.MSD309.BP85 mainboard. [Elektroda, stiff12, post #17020275]
- Diagnostic readings reported: 12 V and 5 V rails present during failure. [Elektroda, stiff12, post #16991956]
- LED backlight rail measured around 42 V on this unit. [Elektroda, stiff12, post #16992315]
- Strips are wired in series; one open LED can black out the screen. [Elektroda, stiff12, post #17119654]
- Final fix: replacing the LED strips (“slats”) restored the picture. [Elektroda, stiff12, post #17121885]
How do I fix “no picture” when 12 V and 5 V are present?
Treat it as a backlight fault. In this case, one LED on a strip was open, disabling the entire series string. Replace the faulty LED strip(s) or the bad LED if you have tools and skills. After replacement, the picture returned, confirming the diagnosis. [Elektroda, stiff12, post #17118753]
What are the exact model and board identifiers for this issue?
Model: Blaupunkt 32/1471/GB‑5B‑HBKUP‑EW. Mainboard: TP.MSD309.BP85. Sharing these identifiers speeds parts matching and forum help. [Elektroda, stiff12, post #17020275]
Are the LED strips in this TV wired in series or parallel?
They are in series. One open LED breaks the circuit and the entire backlight shuts off. This is why a single bad diode can darken the whole panel. [Elektroda, stiff12, post #17119654]
What backlight voltage should I expect on this set?
Approx. 42 V was observed on the LED backlight rail during troubleshooting. This indicates the driver was energized but the series string was open. [Elektroda, stiff12, post #16992315]
Can a single failed LED kill the entire screen?
Yes. With series wiring, one open LED interrupts current to all LEDs, producing a completely dark image even if other rails are good. “One LED is off.” [Elektroda, stiff12, post #17118753]
I replaced the JCS7N65FB MOSFET and still have no picture—what next?
Power‑stage swaps won’t fix an open LED string. In this thread, replacing a JCS7N65FB changed nothing. Shift focus to testing and replacing the LED strips. [Elektroda, stiff12, post #17089425]
What’s a quick 3‑step way to check the backlight on this model?
- Do a flashlight test on a dark screen to confirm image presence.
- Measure the LED rail at the connector for activity.
- Expose and test strips; replace faulty slats to restore light.
“Slats replaced and problem solved.” [Elektroda, stiff12, post #17121885]
Should I replace one LED or all strips?
Replacing entire strips is the most reliable field fix. It balances brightness and color across the panel and avoids repeat teardowns. Here, replacing the slats resolved the issue. [Elektroda, stiff12, post #17121885]
What voltage readings suggest the power board is alive?
Seeing stable 12 V and 5 V rails indicates the supply and mainboard are up. If the screen is still dark, suspect the LED backlight path next. [Elektroda, stiff12, post #16991956]
How should I share details so others can help faster?
Read labels and post model, product, serial, and board codes in text, not only photos. As one expert put it, write them “in letters!” [Elektroda, mirex, post #16992452]
Who should attempt this repair?
If board IDs and measurements confuse you, hand the job to a TV technician. “It’s best to have someone fix it” when you’re stuck. [Elektroda, mirex, post #17011517]
What confirmed the root cause in this case study?
After finding a single dead LED on the strip, replacing the LED slats restored the backlight and picture. That verified the backlight as the failure point. [Elektroda, stiff12, post #17121885]
