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

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.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.