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Vestel 17IPS72 Power Board Won't Turn On: No 5V-STBY, Common Faults, Repair Tips

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User question

17IPS72 не включается

Artificial Intelligence Response

Direct answer to the question

  • Symptom “17IPS72 does not power up/no standby” is most often a failure of the standby SMPS on the PSU itself, not the TV mainboard.
  • First confirm mains in, fuse OK, and ~320–340 VDC on the primary bulk capacitor. If present but there is no 5V-STBY at the output connector, focus on the standby PWM section: the small VCC electrolytic (typically 22–47 µF / 50 V, often marked C313/C316), the startup resistors (megaohm range), the optocoupler/TL431 feedback, and the standby PWM IC (commonly ICE3BR1765J on many 17IPS72 variants; some revisions use MP150GJ).
  • Shorted secondary Schottky on the 5 V rail is another frequent cause; check and replace if shorted.

Detailed problem analysis

  • Architecture overview

    • 17IPS72 is a Vestel flyback-based SMPS with a dedicated always-on standby converter producing 5V-STBY, plus main rails (e.g., 12 V/24 V) enabled via PS_ON from the mainboard. The standby converter runs from rectified mains (~325 VDC with 230 VAC input) and must be healthy for the front LED/microcontroller to wake the set.
    • Controller variants:
    • Many 17IPS72 revisions use Infineon ICE3BR1765J (CoolSET) as the standby PWM/MOSFET combo.
    • Some revisions use MPS MP150GJ or similar 8‑pin PWM. The exact designator and pinout differ by board revision; component IDs like C313/C316 for the VCC electrolytic are common but may vary.

  • What to measure and why 1) Primary side input

    • Mains fuse (F): must be continuous. If open, do not bridge; find the short (bridge rectifier, primary MOSFET inside CoolSET, or an NTC/inrush issue).
    • Bridge rectifier: diode-test for shorts. If OK, power via series bulb/variac and measure bulk capacitor: expect ~320–340 VDC (230 V mains) or ~160–170 VDC (120 V mains). For a “no-standby” fault the PFC, if present, is normally idle (you will not see 380–400 V until the set starts). 2) Standby VCC generation
    • Startup path: one or more high-value resistors (typically 1–5 MΩ total) feed the PWM VCC from the ~325 V rail for initial start. Opened resistors = VCC never reaches the start threshold.
    • VCC electrolytic: a small 22–47 µF/50 V cap near the PWM IC stabilizes VCC. High ESR/low C causes undervoltage lockout cycling (tick/no start) or dead start.
    • PWM thresholds (typical): ICE3BR1765J starts around 17–18 V VCC and turns off near 9–10 V. If you see VCC rising to only 10–12 V and collapsing, suspect the startup network or the VCC cap. 3) Secondary side (before suspecting the PWM IC)
    • Check 5V-STBY rail at the output connector (cold ground reference). A dead short (≈0 Ω/continuous beep) indicates a shorted Schottky diode on the 5 V rail or a failed low-voltage electrolytic. Lift one leg or remove the diode to confirm.
    • TL431 + optocoupler feedback: a leaky TL431 or failed PC817 can hold the primary off or force bad regulation. Replace if suspect. 4) Controller device health
    • If secondary is not shorted and VCC is correct but there is no switching, the controller is likely bad (ICE3BR1765J/MP150GJ). Also inspect the primary snubber (RC/TVS) around the transformer; a shorted snubber component can kill the controller. 5) Soldering/mechanics
    • Heavily stressed joints at transformer pins, power resistors, inductors, and connectors often crack; resolder as needed. Carbonized PCB/tracks around hot parts can create leakage paths—clean and seal.

  • Decision tree (practical)

    • Fuse blown → test bridge and primary switch (inside CoolSET or discrete MOSFET). Replace blown parts and check snubber/feedback before reapplying power.
    • Fuse OK + ~325 V on bulk + no 5V-STBY:
    • Check 5V rail for short. If shorted → replace Schottky/capacitor.
    • If not shorted → measure PWM VCC. If VCC never reaches start threshold → replace VCC cap (C313/C316) and check/open startup resistors; verify ~1–5 MΩ from bulk+ to VCC node.
    • If VCC reaches ~18 V but no drive → replace controller IC; check optocoupler/TL431.
    • 5V-STBY OK but set dead → shift focus to mainboard (local regulators, PS_ON logic, firmware).

Current information and trends

  • Field reports on 17IPS72 commonly point to the small VCC electrolytic (22–47 µF/50 V, often labeled C313 or C316) as the dominant failure, followed by open startup resistors and shorted 5 V Schottkys. Many successful repairs simply replace the VCC cap with a low-ESR 105 °C grade and, if needed, the ICE3BR1765J controller.
  • Multiple board revisions exist; ICE3BR1765J is prevalent, though MP150GJ is seen on some runs. Always verify your exact board print and IC type before ordering parts.

Supporting explanations and details

  • Why the tiny VCC cap matters: On cold start, the PWM charges its VCC via a tiny current through high-value resistors. A dried-out VCC cap cannot hold charge; the IC falls below UVLO, shutting off before secondary bias can sustain VCC. The result is a dead supply or faint ticking.
  • Secondary short behavior: A shorted 5 V Schottky clamps the flyback energy, the primary detects overcurrent and latches or hiccups, often with no visible LED.
  • Optocoupler/TL431 role: They close the feedback loop. If open/leaky, the primary either never starts or runs erratically and shuts down.

Ethical and legal aspects

  • Safety: Primary side carries lethal potentials. Use an isolation transformer and a series incandescent limiter for first power-up after repair. Discharge the bulk capacitor and verify <10 V before handling.
  • Don’t bypass protective devices (fuse, NTC, safety capacitors). Use certified replacement parts with equal or higher voltage and temperature ratings. Observe creepage/clearance; restore any charred board areas properly.

Practical guidelines

  • Replacement recommendations
    • VCC electrolytic: 47 µF/50 V, low-ESR, 105 °C; replace proactively.
    • Startup resistors: measure out of circuit; replace any drifting >10%. Consider series parts totaling the original megohm value at 0.5–1 W rating depending on layout.
    • Optocoupler: PC817 or specified equivalent; TL431 as per datasheet (use reputable brands).
    • Schottky on 5 V: match current/voltage/thermal specs; ensure proper heatsinking.
    • Controller IC: ICE3BR1765J or MP150GJ per your PCB; replace with antistatic handling; inspect/snubber parts at the same time.
  • Test method
    • With mainboard/backlight disconnected, bring up the PSU via a 60–100 W series bulb. Verify stable 5V-STBY. If stable, add a dummy load (e.g., 100–120 Ω, 2–3 W) on 5V to check regulation.
    • If you have a lab supply: feed the controller VCC pin at its operating voltage limit (per datasheet, typically 15–18 V max) through a resistor to see if the PWM starts; do this only if you’re certain of the pinout and isolation boundaries.
  • Common pitfalls
    • Replacing only the blown controller without curing root causes (bad VCC cap/snubber) leads to repeat failures.
    • Misidentifying grounds: measure secondary rails against cold ground only.

Possible disclaimers or additional notes

  • Component designators (C313/C316, IC type) can vary between 17IPS72 sub-revisions; verify on your exact PCB.
  • If the bulk capacitor never reaches ~320–340 V on 230 VAC, the fault is upstream (fuse, input filter, bridge, NTC, cracked traces).

Suggestions for further research

  • Obtain the exact schematic/boardview for your 17IPS72 revision to trace the startup network and confirm designators.
  • Review the controller datasheet (ICE3BR1765J or MP150GJ) for UVLO thresholds, soft-start behavior, and typical application circuits to guide measurement points.
  • Study field repair threads specific to your TV model paired with 17IPS72 for variant-specific tips (connector pinout, typical shorts).

Brief summary

  • For “17IPS72 doesn’t turn on,” verify mains and bulk ~325 V first. If present but no 5V-STBY, concentrate on the standby flyback: replace the small VCC electrolytic (22–47 µF/50 V, low-ESR), check/replace open startup resistors, test the 5 V Schottky and the PC817/TL431 feedback, and replace the PWM IC (ICE3BR1765J or MP150GJ) if VCC is correct but there is no switching. Use a series bulb and isolation for safe bring-up.

If you can, share: whether the front LED ever lights, the measured bulk voltage, VCC on the PWM IC at power-up, and resistance of the 5 V rail to cold ground. With those four data points I can narrow the fault to a handful of parts and give you exact test pads/designators for your revision.

User question

When everything is connected the tv starts up but the backlight never turns on. The backlight turns on with a working power supply. I have the version with MP150GJ. The 5V rail is unpopulated (Q18 and componets around that area) and is supplied by the tv main board instead. I only have the power supply available at the moment so I can not meassure with everything hooked up. How would I trick the board into starting up from standby without the 5V rail?

Artificial Intelligence Response

Direct answer to the question

You generally cannot bring that 17IPS72 variant fully out of standby with only a jumper if the onboard 5V section around Q18 is not populated. In your version, the main board provides the housekeeping/control rail, so on the bench you must inject an external low-voltage supply on the secondary side and then assert the control pins. Vestel service documentation for related chassis shows the same general control scheme: standby/control rails on the main board side, plus logic lines such as STBY_ON/OFF, BACKLIGHT_ON/OFF, and BACKLIGHT_DIM/PWM. (vestelservice.com)

Practical method:

  • Use an external 3.3V to 5V DC source, current-limited.
  • Connect its negative to cold ground only, not primary ground. Vestel documentation distinguishes cold ground on the secondary/output side from hot ground on the primary. (elektroda.com)
  • Feed that external logic supply into the node that the main board normally uses to provide the missing housekeeping rail.
  • Then drive:
    • PS_ON / STBY_ON-OFF
    • BL_ON / BACKLIGHT_ON-OFF
    • DIM / PWM / BACKLIGHT_DIM
  • Do not put 12V on any of those logic pins. They are logic-level controls, not power rails. Vestel manuals show these as signal nets associated with standby/backlight control, not as supply outputs. (vestelservice.com)

The most important correction to the sample answers is this: on your board revision, the missing 5V rail is the reason a simple PS_ON jumper is not enough. You need to recreate the external housekeeping logic supply first.

Detailed problem analysis

Your board variant uses MP150GJ, which MPS identifies as an offline primary-side regulator. That tells us the controller itself is part of the AC-DC power architecture, but it does not automatically mean your specific Vestel sub-revision generates all needed secondary-side logic rails locally. In your case, the depopulated Q18 area strongly indicates Vestel made a board revision where the main board supplies the low-voltage control rail instead. (monolithicpower.com)

That leads to an important distinction:

  1. Main PSU startup

    • The power board must be told to leave standby.
    • That is typically done by a logic input such as PS_ON or STBY_ON/OFF.

  2. Backlight startup

    • Even if main rails come up, the LED driver usually still needs:
      • BL_ON / BACKLIGHT_ON-OFF
      • DIM / PWM / BACKLIGHT_DIM
    • Vestel main board schematics explicitly show these backlight control nets. (vestelservice.com)

So if you want to bench-run the PSU and see the backlight section act alive, you usually need more than one signal.

What this means electrically

Because your onboard 5V standby section is absent:

  • The secondary-side control transistor network may be unpowered.
  • The opto/logic interface that interprets PS_ON may be unpowered.
  • The LED enable/dimming interface may also be unpowered.

Therefore:

[ \text{No external housekeeping rail} \Rightarrow \text{PS_ON may do nothing} ]

That is why the right bench method is:

Bench-start sequence

  1. Identify cold ground

    • Use the secondary/output connector ground.
    • Do not reference anything to bulk-cap negative or primary heatsink unless you are intentionally measuring the hot side. Vestel repair guidance explicitly separates hot and cold grounds. (elektroda.com)

  2. Inject external low-voltage supply

    • Start with 3.3V if you are unsure.
    • If the control rail is clearly labeled 5V from main board, use 5V.
    • Set current limit initially around 100mA to 200mA.

  3. Assert the run command

    • Apply the same logic rail to PS_ON / STBY_ON-OFF through about 1kΩ to 4.7kΩ.
    • Do not hard-short unknown pins until you trace them.

  4. Assert backlight enable

    • Apply the same logic rail to BL_ON / BACKLIGHT_ON-OFF through 1kΩ to 4.7kΩ.

  5. Provide dimming command

    • Many LED driver DIM pins will respond to:
      • PWM, or
      • a DC level for a quick test
    • For bench testing, a steady 2.5V to 3.3V through a resistor is often enough to request nonzero brightness.

  6. Keep the LED load connected

    • If the LED strips are disconnected, the boost converter may briefly rise and immediately trip OVP.
    • In that case a DMM may show nothing steady even though the driver is trying to start.

Why the symptom matters

You stated:

  • TV starts up with everything connected.
  • Backlight never turns on with this PSU.
  • Backlight turns on with a working PSU.

That strongly suggests one of two things:

  • Control path problem on the suspect PSU:

    • BL_ON / DIM interface not being interpreted correctly.
    • missing pull-up/pull-down / small transistor fault around those inputs.

  • LED driver section fault on the suspect PSU:

    • open feed resistor/fuse to LED driver
    • shorted boost MOSFET
    • bad boost diode
    • failed LED controller IC
    • bad current-sense network

In other words, even if you learn how to force it on, that may only confirm the likely conclusion: the backlight power stage on that board is faulty.

Current information and trends

MPS currently lists MP150 as an active offline primary-side 2W regulator, consistent with its use in low-power AC-DC housekeeping functions. (monolithicpower.com)

Current Vestel service manuals for related chassis still show the same design pattern:

  • logic rails such as 5V_STBY / 3V3_STBY
  • control signals such as STBY_ON/OFF
  • backlight control signals BACKLIGHT_ON/OFF and BACKLIGHT_DIM. (vestelservice.com)

The practical trend in these boards is that revisions differ. A method that works on one 17IPS72 revision may fail on another because:

  • PSU-side 5V standby may or may not exist
  • PS_ON polarity may differ
  • LED driver controller part may change
  • connector naming may remain similar while implementation shifts

So for your exact board, do not assume pin polarity from another revision. Treat the Vestel documentation as architecture guidance, then verify on your PCB.

Supporting explanations and details

Safest way to “trick” it on

If you have only the PSU on the bench, do this:

Step Action Notes
1 Find cold ground Secondary ground only
2 Inject 3.3V or 5V to the missing housekeeping input Current-limit supply
3 Drive PS_ON/STBY_ON-OFF via 1k–4.7k Try logic-high first
4 Drive BL_ON similarly Needed for LED section
5 Drive DIM/PWM with 2.5–3.3V or PWM For a quick test, DC is acceptable
6 Leave LED strings connected Otherwise OVP can shut it down instantly

If you do not know PS_ON polarity

Use this method:

  • Measure resistance from PS_ON to ground with board unpowered.
  • Measure resistance from PS_ON to the injected logic rail.
  • If it appears already pulled low, it may want a high signal.
  • If it appears already pulled high, it may want a low signal.
  • When testing, use a series resistor so a wrong guess does not directly short anything.

A good conservative first attempt is:

  • inject 3.3V
  • feed PS_ON through 2.2kΩ
  • feed BL_ON through 2.2kΩ
  • feed DIM through 2.2kΩ

That is much safer than hard-bridging.

What not to do

  • Do not inject voltage into the MP150 VCC pin on the primary side.
  • Do not connect your bench supply negative to the primary bulk capacitor negative unless you are deliberately working on the hot side.
  • Do not bridge logic pins to 12V or 24V.
  • Do not expect steady LED output with no LED load attached.

Ethical and legal aspects

  • This is mains-powered equipment; the primary side carries hazardous voltages.
  • Use an isolation transformer if available, especially for oscilloscope work.
  • Respect creepage/clearance and do not defeat isolation barriers.
  • If this repair is for resale or customer return, final testing should include electrical safety checks, insulation integrity, and thermal soak.

Practical guidelines

What I would do next, in order

  1. Trace the connector pins

    • Identify:
      • GND
      • main-board-supplied low-voltage rail
      • PS_ON or STBY_ON/OFF
      • BL_ON
      • DIM/PWM

  2. Bench inject the missing logic rail

    • 3.3V first if uncertain
    • 5V if the board labeling clearly indicates 5V input from main board

  3. Assert run + backlight signals

    • Through resistors, not hard wires

  4. Check whether main rails appear

    • 12V / 24V as applicable

  5. If main rails appear but backlight does not

    • Fault is likely local to LED driver section

  6. Power off and test the LED stage statically

    • MOSFET D-S short
    • boost diode short/open
    • low-ohm feed resistor/fuse open
    • sense resistors open
    • controller VCC short to ground

Likely fault locations on the bad board

Given your symptom, I would prioritize:

  • LED boost MOSFET
  • series feed resistor or fuse into LED driver
  • boost diode
  • LED controller IC
  • solder cracks around LED transformer/inductor or hot components

Possible disclaimers or additional notes

  • I cannot guarantee PS_ON polarity from the information provided alone.
  • I also cannot guarantee whether your board needs 3.3V or 5V on the control rail without seeing the connector labels or tracing the net.
  • If you send a clear photo of the connector area and the Q18 unpopulated section, I can usually tell you exactly where to inject voltage and which pin to drive.

Suggestions for further research

To finish this cleanly, the best next steps are:

  • obtain the exact 17IPS72 revision schematic
  • photograph the main-board connector silkscreen
  • identify the LED driver controller marking
  • trace which connector pin feeds the missing Q18-area rail

A continuity map of 5–6 connector pins would likely be enough to remove the guesswork.

Brief summary

For your MP150GJ / no-onboard-5V version, the correct answer is:

  • A jumper alone is not enough.
  • You must externally recreate the missing housekeeping rail on the secondary side.
  • Then assert PS_ON/STBY_ON-OFF, BL_ON, and usually DIM/PWM with logic-level voltage through resistors.
  • Keep the LED load connected, or the LED driver may pulse and shut down on OVP.
  • If the board still will not light the backlight while a known-good PSU does, the defect is very likely in the LED driver section, not just standby logic.

If you want, send:

  1. a photo of the connector labels, and
  2. a photo of the unpopulated Q18 area,

and I will mark the exact bench-start connections.

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