How to Repair a Vestel 17PW20-1 SMPS

How to Repair a Vestel 17PW20-1 SMPS

A Vestel 17PW20-1 is a switch mode power supply (SMPS) that is used in many LCD TVs. It has a resonant PFC circuit that converts the AC input voltage to a high DC voltage, and a sync circuit that generates the PWM signals for the output voltages. The SMPS also has various protection features, such as overvoltage, overcurrent, and overtemperature.

vestel 17pw20 1 smps schematic diagram a

If you have a Vestel 17PW20-1 SMPS that is faulty, you may be able to repair it by following these steps:

• Check the fuse F800 on the primary side of the SMPS. If it is blown, replace it with a new one of the same rating (3.15A).

• Check the rectifier diodes D800 and D801 on the primary side of the SMPS. If they are shorted or open, replace them with new ones of the same type (GBU4M).

• Check the electrolytic capacitors C800 and C801 on the primary side of the SMPS. If they are bulged or leaking, replace them with new ones of the same value (33uF 50V).

• Check the PFC MOSFET Q807 on the primary side of the SMPS. If it is shorted or open, replace it with a new one of the same type (MTP6N60E/SSP7N60A).

• Check the PFC diode D809 on the primary side of the SMPS. If it is shorted or open, replace it with a new one of the same type (STPS_3P_10L60CFP).

• Check the PFC controller IC802 on the primary side of the SMPS. If it is damaged or burned, replace it with a new one of the same type (SG2525A).

• Check the resonant MOSFETs Q813 and Q814 on the primary side of the SMPS. If they are shorted or open, replace them with new ones of the same type (MTP6N60E/SSP7N60A).

• Check the resonant diodes D815 and D816 on the primary side of the SMPS. If they are shorted or open, replace them with new ones of the same type (STPS_3P_10L60CFP).

• Check the resonant controller IC807 on the primary side of the SMPS. If it is damaged or burned, replace it with a new one of the same type (IRF7314).

• Check the output voltages on the secondary side of the SMPS. They should be +5V, +12V, +24V, +33V, and +400V. If any of them are missing or incorrect, check the corresponding output circuits for any faulty components.

You can find more details about the Vestel 17PW20-1 SMPS schematic diagram in these sources[^1^] [^2^] [^3^].

The PFC circuit is responsible for boosting the DC voltage to around 400V and maintaining a high power factor. It uses a boost converter topology with a PFC inductor L802 and a PFC capacitor C819. The PFC MOSFET Q807 is switched on and off by the PFC controller IC802, which senses the input current and the output voltage. The PFC diode D809 conducts when the PFC MOSFET is off, transferring the energy stored in the PFC inductor to the output capacitor C819. The PFC controller IC802 also monitors the output voltage and adjusts the duty cycle of the PFC MOSFET to keep it within a safe range.

The sync circuit is responsible for generating the PWM signals that control the resonant MOSFETs Q813 and Q814. It uses a sync transformer TR804 that isolates the primary and secondary sides of the SMPS. The sync controller IC807 receives the feedback signals from the output circuits and compares them with the reference voltages. It then generates two complementary PWM signals that are sent to the primary side of the sync transformer TR804. The secondary side of the sync transformer TR804 drives the gates of the resonant MOSFETs Q813 and Q814 through two gate drivers Q811 and Q812.

The resonant circuit is responsible for converting the 400V DC voltage to various AC voltages that are fed to the output transformers. It uses a resonant capacitor C836 and a resonant inductor L810 that form a series resonant tank. The resonant MOSFETs Q813 and Q814 are switched on and off by the PWM signals from the sync circuit, creating a high-frequency AC voltage across the resonant tank. The resonant diodes D815 and D816 rectify this AC voltage and provide a DC voltage to the primary windings of the output transformers TR801, TR802, TR805, and TR806. e0e6b7cb5c