Hisense tc2100sa was killed by lightning

[GIDEONELECTRO]

I need help. I am repairing a Hisense tc2100sa was killed by lightning. I checked the primary smps and the voltages at the switching transistor are 312vdc at the collector leg and-1.4 at the base leg. I checked and changed all the bad components in the primary smps and the voltages are low on the secondary smps. I changed all bad components in the feedback circuit and secondary smps and all voltages are still low.

Main IC LA76810A
IC LC863328B
IC LC863328B

 

[BradtheRad]

It sounds as though your unit is an uninterruptible power supply, or a power inverter, or battery charger.

The IC's are vulnerable of course. It's hard to be sure whether they're still good. Get many ohm readings across pairs of pins (Use highest ohm range because it sends through the least current out through the leads). Identical ohm readings suggest the IC's innards are fused together.

* Can you run individual tests on smps #1 and smps #2?

* Can you determine whether voltage drop is due to smps #1 inability to sustain a load?
Or is the fault with smps #2?

* Can you disconnect smps #1 from smps#2? Can you connect a light resistive load to smps #1, and read output voltage? Then, reduce ohm value and watch to see whether smps #1 output voltage suffers. Whether it overheats, etc.

* Can you construct a power supply of 312V? And apply it to smps 2? Watch to see if it wastes power, overheats, etc.?

 

[nnaveli]

hi,disconnect all secondary output diodes and horizontaloutput transistor(hot)leaving only the high voltage (ht)diode connected to load(60/100watt-filament bulb and ground.power the set ,measure ht voltage acrossyour load..1)is any votage?ifnotgo to urprimary side mostlikely failing parts fuses,ptc,diodes ,resistors smps ic or transistors and optocouplers.If got voltage check is 110/130v depending on the screen size,then put back other diodes one by one still monitoring ht voltage.