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December 18, 2025
I had a Hisense 43H77G that had decided to call it quits, offering nothing but a red LED that blinks twice before plunging back into darkness. I’ll be the first to admit: I’m not experienced in TV repair, but every broken device is a learning journey and it wasn't working anyway, so I grabbed my multimeter and decided to dive into the belly of the beast.
Upon opening the set, I found a single PCB (model RSAG7.820.9829) acting as both the power supply and the mainboard. Without a service manual or schematics to guide me, I had to rely on old-fashioned detective work. Initial tests showed that the main filter capacitors were charging and power was reaching the secondary side of the board. I could see voltages appearing briefly before the system shut down. The diodes and resistors I tested looked within spec, but the rapid shutdown made it nearly impossible to get a steady reading of the power rails.
Some research suggested to me that Hisense TVs are notorious for eMMC (storage) failures, but before jumping to that depressing conclusion, I decided to check the electrolytic capacitors. Using an ESR (Equivalent Series Resistance) meter in-circuit can be tricky because other components—like inductors—can mess with the readings. I found one capacitor that read 12–13 ohms—suspiciously high. I pulled it and two "sister" capacitors from the same series for comparison. While the others sat at 2 ohms, the questionable one remained high. I looked up the datasheet, but instead of ESR, it listed "Dissipation Factor" which is measured at 120Hz instead of the 100kHz used by my ESR meter.
Math Note: You can technically calculate ESR from the dissipation factor but since most ESR meters test at 100kHz, the numbers rarely line up perfectly for an easy comparison.
I ordered a suitable replacement for the questionable capacitor, and a few other unique ones which I didn't have on hand just to be safe but I had a nagging feeling the problem lived elsewhere.
Sure enough, after receiving and swapping the suspicious capacitor there was no change.
I started probing the inductors again to see if I could identify which power rail was at fault. I noticed a 0V reading on inductor L44, which didn't seem right. The nearby components didn't seem to be the source of the perceived short, so I removed the inductor. Underneath I discovered there was a via that lead to an IC labelled CS602-A0G.
The L44 inductor which appear shorted.
The IC at the end of the path from L44.
I couldn't find a datasheet for the chip, but did find a pinout that someone had put together. The pin that was connected to the inductor was labelled LX1 on the diagram, and the pin definitely seemed to be shorted to ground. Was this by design? One way to figure that out would be to remove the IC and check to see if the pad was still connected to ground.
The CS602-A0G is a QFN-88 package and so removing it was not easy as it has a massive ground pad underneath that acts like a heat sink. In the process of removing it, I accidentally knocked a few neighboring tiny components loose. I reattached the bumped components and with the chip off, I realized the "short" LX1 that led to L44 was actually by design—the pin was tied directly to that massive ground plane. However, the removal allowed me to perform "DNA testing" on the chip itself using diode checks.
I probed the internal protection diodes of the CS602 and during that process you would normally expect a forward voltage drop between 0.4V and 0.8V. During the probing it felt like a red flag popped up in that the VGL (Voltage Gate Low) pin showed a voltage drop of 2.2V. Working further around the chip I found a dead zone.
Pins 24 through 44 which I believe are tied to the output stage were all reading OL This "dead zone" covers what I understand to be the critical high-voltage timing signals that drive the LCD panel rows.
CLK_OUT1–12: The clock pulses that scan the image down the screen.
STV_OUT: The "Start Vertical" signal telling the panel to start a new frame.
VSS: The reference point for the "Off" state of the gate.
The 2.2V drop on VGL and the other OL readings suggest the internal silicon junctions or bond wires "blew open" possibly during a catastrophic over-voltage event. Because the internal logic couldn't power itself, it couldn't respond to the CPU's "Hello" on the data lines (SDA/SCL), causing the system to abort the boot process.
It would seem the CS602-A0G was fried and while I likely found the culprit, I decided to stop there. Replacing a QFN-88 with my current equipment would be challenging and prone to solder bridging. Even if I successfully replaced the chip, there are some indications online that the chip can be programmed, and thus may need further unknown adjustments. On top of that there’s a possibility that the LCD panel itself was damaged when the chip went nuclear. Toss in the looming threat of a future eMMC failure, and the repair just doesn't make economic sense. It’s frustrating to hit the limits of your equipment or the "repairability ceiling," but knowing when to walk away is just as important as knowing how to use a soldering iron. This Hisense might be headed for the recycling center (minus a few scavenged parts) but the knowledge gained stays with me.
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