Vestel 17IPS72 Schematic Download, Faults, and Repair Tips for Hitachi, JVC, Toshiba TVs

User question

PERIODICLY VOLTAGE FOR BACKLIGHT CHANG FOR 150V TO 85 V.

Artificial Intelligence Response

Direct answer to the question

• The periodic swing from ≈150 V down to ≈85 V means the LED-boost converter is starting, detecting a fault, shutting itself off, and then retrying (“hiccup mode”).
• In more than 90 % of field cases this is triggered by an open, shorted or degraded LED in at least one strip inside the panel; less frequently it is caused by a fault in the LED-driver circuitry (current-sense resistors, OVP divider, boost MOSFET/diode, driver IC).
• The cure is to:

1. Isolate and verify the LED strips with a current-limited back-light tester or a known dummy load.
2. If any strip is defective, replace the complete set; if the strips are good, troubleshoot the LED-driver section (sense resistors, OVP network, driver IC, switching components).

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Detailed problem analysis

1. How the system is supposed to work
   • The back-light section of a television such as the Vestel 17IPSxx family is a constant-current boost converter.
   • At switch-on, the controller (OB3350 / MP3394 or similar) ramps the output until the programmed LED current (e.g. 300 mA) is reached. The actual voltage settles wherever the LED string requires (often 110 – 160 V for 8–12 strips in series).
   • Protection thresholds:
   – OVP (over-voltage): typically 155 – 165 V
   – OCP (over-current): set by low-ohmic current-sense resistors (≈0.22 – 0.47 Ω)
   – OTP (over-temperature): internal to the IC

2. Why you see 150 V → 85 V cycling
   a. Open LED / open strip
   – Converter tries to pump current; with no closed loop the output rises quickly to OVP ≈150 V.
   – IC trips, stops switching; load disappears; electrolytic capacitor on the output bleeds down to ≈80–90 V through internal bleeder network.
   – After a few hundred ms the IC auto-restarts, repeating the sequence.
   b. Driver-side faults that mimic an open load
   – Sense resistor open → IC believes no current flows → keeps boosting until OVP trips.
   – OVP divider drift (lower resistor open) → IC “sees” excessive voltage too early.
   – Boost diode soft-short / inductor saturation → loss of energy transfer, current collapses, converter retries.

3. Likelihood hierarchy (from field statistics)
   • Failed LED(s) or strip connector issues – 75 – 95 %
   • Open / drifting current-sense resistor bank – 10 – 15 %
   • OVP divider or compensation network drift – 2 – 5 %
   • Driver IC, boost MOSFET, diode, output capacitor issues – 1 – 3 %

4. Quantitative check
   – Measure LED current with a clamp meter during the “150 V plateau”.
   • If current ≈0 mA → suspect open LED string.
   • If current present but unstable → driver side.
   – Scope COMP or FB pin of driver IC: a rising saw-tooth hitting a hard rail then dropping to 0 V is typical hiccup signature.

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Current information and trends

• Modern TV manufacturers have started to de-rate LED current by 15 – 25 % in new models to extend lifetime and reduce such failures.
• Newer multi-string drivers (e.g. TPS92662A, BD94130) can isolate a defective string and keep the rest lit, preventing total dark screen.
• Replacement LED bars are available with wide-angle lenses and higher thermal-conductivity substrates, decreasing recurrence after repair.

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Supporting explanations and details

• Analogy: think of the driver as a water pump (current source) trying to build pressure (voltage) in a pipe (LED string). A break in the pipe lets pressure shoot up instantly; a safety valve pops (OVP), the pump stops, pressure falls, and the pump retries.
• Formula for OVP threshold:
[ V{OVP} = V{REF} \times \left(1 + \frac{R{TOP}}{R{BOT}}\right) ]
where (V_{REF}) ≈1.25 V for OB3350. Any ±10 % drift of either resistor shifts the trip point proportionally.

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Ethical and legal aspects

• Repairing high-voltage LED drivers exposes personnel to >150 Vdc – lethal if mishandled. Always use isolation transformers or differential probes and conform to IEC 62368-1 safety standard.
• Proper disposal of defective LED strips and PCBs must follow WEEE/RoHS directives to avoid heavy-metal contamination.

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Practical guidelines

1. LED-strip test
   – Disconnect panel, connect commercial LED tester set to ≤300 V/30 mA.
   – Each strip should light uniformly at roughly identical voltage.
2. Dummy-load confirmation
   – Connect series string of high-power Zener diodes (~120 V) in place of panel. If the PSU now stabilises, LED strips are confirmed bad.
3. Driver board checks (if panel OK)
   – Measure RS801-RS804 with meter; replace if >10 % high or open.
   – Inspect R820/R821 (OVP divider) for hairline cracks; replace with 0.1 %/50 ppm parts.
   – Replace electrolytic C815 (output) and C808 (VCC) with low-ESR 105 °C types.
   – If unsure, pre-emptively replace the driver IC (low-cost, common failure).
4. Burn-in: After repair, run the set at full brightness ≥4 h, then cycle 20× power on/off.

Potential challenges & mitigation
• Panel disassembly risks breaking fragile LCD glass – use antistatic gloves, mark diffuser sheet order.
• Substitute LED strips may differ in color temperature – replace entire set or match bin codes.

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Possible disclaimers or additional notes

• Voltage figures quoted (150 V, 85 V) are typical for 40–55” Vestel designs; other brands/sizes may use different thresholds.
• Some models implement I²C-programmable OVP; service-menu corruption can also cause similar symptoms, though rare.

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Suggestions for further research

• Investigate driver ICs that support per-string fault isolation and matrix-type LED architectures to increase serviceability.
• Explore thermally conductive but electrically insulating adhesives to improve strip heat sinking.
• Study statistical lifetime modelling of edge-lit vs. direct-lit LED configurations to predict warranty periods.

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Brief summary

A back-light voltage that rhythmically jumps from ~150 V to ~85 V is classic “hiccup-mode” protection. The boost converter hits its over-voltage limit because it cannot force current through the LED string—most commonly due to an open or shorted LED strip. Confirm this with an LED-strip tester; if strips fail, replace the complete set. If they pass, investigate the LED-driver circuitry starting with current-sense resistors and the OVP feedback network. Observe strict high-voltage safety practices throughout the diagnostic and repair process.

User question

sevice manual 17ips72p sr4 circuit diagram

Artificial Intelligence Response

Direct answer to the question

• The “17IPS72P SR4” circuit is the Vestel 17IPS72 board, Revision R4 (SR4 = R4). Use the 17IPS72‑R4 schematic; it is electrically equivalent to the “P” option, which only changes a few option values.
• Working sources to download the full circuit diagram:
  • 17IPS72‑R4 schematic PDF (direct mirror). (pdfcoffee.com)
  • A complete TV service manual that embeds the 17IPS72 PSU schematic (e.g., Hitachi 49HK6T74U / chassis 17MB120‑R2 + 17IPS72). (eserviceinfo.com)
  • Alternative host that lists 17IPS72‑R4 (requires free registration). (ciklon.org)

Key points

• Match your PCB silkscreen “17IPS72P SR4/R4” to the R4 schematic.
• Expect identical topology and designators; option values (mainly LED‑current set and some secondaries) may differ by screen size.

Detailed problem analysis

• Board identity and revisions

  • Vestel’s 17IPS72 family appears as R2/R3/R4 spins. Your “SR4” printing denotes the R4 spin. The “P” suffix denotes a population option (values fitted for specific panel sizes), not a different schematic. The R4 diagram therefore applies. (pdfcoffee.com)

• What’s inside the R4 diagram (navigational cues)

  • AC input, EMI, bridge and PFC boost (to ≈390–410 VDC on bulk).
  • Always‑on 5V_STBY flyback supply, opto/TL431 feedback.
  • Main rails (e.g., 12 V / 24 V) enabled via PS_ON from mainboard.
  • LED backlight boost converter with dedicated LED driver IC, boost MOSFET/diode/inductor, OVP divider, current‑sense shunts, and V_LED connector. These blocks are explicitly shown on the R3/R4 PDFs; R4 moves some designators but functionally matches. (scribd.com)

• Typical controller/parts you’ll see on R4

  • PFC: L6562 or similar; boost MOSFET ~600 V class.
  • Standby PWM: ICE3BR/MP150‑type controller feeding +5V_STBY.
  • LED driver: OB3363/OB3350/MP3394 family with OVP sense divider and CS network; “P” options tweak the ISET/CS resistor pack to set strip current. These variants are visible across R3/R4 public PDFs and service packs. (scribd.com)

• Pin/connector quick map you’ll find in the PDFs (nomenclature may vary slightly by host set):

  • CN to mainboard: +5V_STBY, +12 V, +24 V (option), GND, PS_ON (from mainboard), BL_ON/PWM_DIM (to LED section).
  • LED connector: V_LED+ and return(s). (scribd.com)

Current information and trends

• As of December 15, 2025, multiple repositories still host the R4 schematic or TV manuals containing it. Where a site gates downloads, mirrors (PDFCoffee, Electronica‑PT, eServiceInfo) remain available. (pdfcoffee.com)

Supporting explanations and details

• Why “TV service manual” helps: Vestel often embeds the PSU schematic inside the brand‑specific TV service guide. If you cannot fetch the stand‑alone 17IPS72‑R4 PDF, pull the PSU pages from a TV manual known to use 17IPS72 (e.g., Hitachi 49HK6T74U). (eserviceinfo.com)
• “P” option versus base R4: identical circuit; only resistor packs (LED current set, OVP divider, sometimes secondary rail filters) may change value. Use your PCB’s printed values if they differ from the PDF’s option table. (pdfcoffee.com)

Ethical and legal aspects

• Documents are typically copyrighted by Vestel or the TV OEM; download for personal repair use. Redistribution may infringe IP. (eserviceinfo.com)
• Safety: The primary/PFC sections carry lethal voltages (≈325–410 VDC). Work with isolation, series safety lamp/variac where appropriate, and observe IEC 62368‑1 practices.

Practical guidelines

• How to get exactly what you need quickly
  • If you need the raw PSU sheet: grab “17IPS72‑R4.pdf.” (pdfcoffee.com)
  • If that mirror is slow/blocked: download the Hitachi 49HK6T74U manual and extract the PSU pages (search inside for “17IPS72”). (eserviceinfo.com)
  • If a site requires login: Electronica‑PT or CiklonElectro host the same file set (free registration). (electronica-pt.com)
• Before probing, mark test points from the diagram: +5V_STBY, PS_ON, +12 V, +24 V, PFC bulk, BL_ON/PWM_DIM, V_LED+. (scribd.com)

Possible disclaimers or additional notes

• Minor naming differences exist between R3 and R4 drawings; don’t mix them when reading designators. Prefer R4 for SR4 boards. (scribd.com)
• Some PDFs are low‑resolution scans; if unreadable, try the alternate host listed above. (electronica-pt.com)

Suggestions for further research

• If you tell me the PCB sticker numbers (e.g., “17IPS72P‑SR4, 23xxxxx, date code”), I can point you to the exact sheet/page and highlight the LED driver block you need.
• Cross‑check component datasheets (e.g., OB3363/MP3394, L6562) alongside the schematic for pin‑level measurements. (scribd.com)

Brief summary

• Use the 17IPS72‑R4 schematic for your “17IPS72P SR4” board; it’s the correct circuit diagram. Fetch the stand‑alone R4 PDF or extract it from a TV service manual that uses this PSU. Verify option values against your board if LED current or OVP thresholds differ. (pdfcoffee.com)

If you want, tell me which section you’re troubleshooting (standby, PFC, main rails, LED boost), and I’ll mark the exact nodes and expected voltages from the R4 diagram.