Skyworth LCD TV 32E60HR second time does not boot maintenance example - appliance repair - Huaqiang electronic network

Memory chip

Since I decided to start promoting some technical posts, I thought I'd share one of my own—maybe it's not the best, but I hope it can spark some useful discussions.

Recently, I worked on a Skyworth 32E60HR LCD TV. The indicator light was on, but the TV wouldn't power on properly. After some troubleshooting, I found that the power board was working fine, with all the output voltages—5V, 12V, and 24V—being stable. That meant the issue had to be on the motherboard, model number 5800-A8R650-0020.

I started by checking the DC-DC converter and LDO regulator on the motherboard. Soon, I noticed that the 1.8V output from U18LM1117-ADJ was unstable, only reading around 1.39V. The input voltage to U18, however, was normal. After replacing the faulty U18 with a new AMS1117-ADJ, the output stabilized at 1.82V.

Once the voltage was fixed, I powered the TV back on and sent a signal. The display worked perfectly. The 1.8V from U18 is used to power the DDR2 memory chip, W971GG6JB-18. If this voltage isn’t correct or stable, the main processor may misread the DDR data, leading to boot issues like no startup, slow booting, or even system crashes.

This repair taught me how crucial voltage stability is for memory components in modern electronics. Even a small failure in a low-voltage regulator can cause major problems. I hope this detailed breakdown helps others who might encounter similar issues with their TVs or other devices.

VOUT = 1.25 × (150 + 66) / 150