Hisense 58H6550E - Freezes/Won't turn on

tmhobadcap · 02-19-2023, 03:04 AM

Re: Hisense 58H6550E - Freezes/Won't turn on

As per Diah's suggestion, I should add heavy weight load to the chip while reflowing. Since it is so small, I could only think of pressing the chip with tweeters at the end of the reflowing. I tried several times (maximum temperature setting was 375°C but the results were just the same (Hisense logo appears for a few seconds). I found that the chip could not be moved at 375°C, so I thought may be the temperature was not high enough. I raised the temperature setting to 425°C and tried a few more times, but the results were the same. At 425°C, the chip could be moved and so I took the chip out hoping that cleaning the chip the pcb might help.

After removing the old solder, cleaning and adding new solder, I put it back. But the results were even worst, the tv could not be turn on (no Hisense logo, the standby light keeps red). Does this mean the chip has been damaged? Or putting back the chip must do "reballing" using solder balls and stencils as in some Youtube videos?

Attached Files

Diah · 02-14-2023, 01:28 PM

Re: Hisense 58H6550E - Freezes/Won't turn on

yes.. this is BGA gun

tmhobadcap · 02-14-2023, 01:21 PM

Re: Hisense 58H6550E - Freezes/Won't turn on

Originally posted by Diah

we dont know which kind of gun you are using... if its not for BGA rework. mean the hot air will be blowing with high pressure. and this matter caused shaking at the chip doesn't mater from top or from downside. thought the chip bed points distances between each less than 1/2mm . place weight will keep it in place however the air pressure high.
250-280° will be fine.

My heat gun is as shown on the photo. Is it suitable for BGA rework?

Attached Files

Diah · 02-14-2023, 07:06 AM

Re: Hisense 58H6550E - Freezes/Won't turn on

we dont know which kind of gun you are using... if its not for BGA rework. mean the hot air will be blowing with high pressure. and this matter caused shaking at the chip doesn't mater from top or from downside. thought the chip bed points distances between each less than 1/2mm . place weight will keep it in place however the air pressure high.
250-280° will be fine.

tmhobadcap · 02-13-2023, 08:52 PM

Re: Hisense 58H6550E - Freezes/Won't turn on

Originally posted by Diah

you caused BGA issue on emmc. try again with yours heat gun.. but you need to load heavy weight on emmc to keep it much it can stick at boards during the heat process,

I did the reflowing by blowing hot air from the top. You suggest to load some weight on the emmc. Then I think I should blow the hot air from the bottom side of the pcb (there is no components on the bottom side). What temperature do you suggest I should use? Will the heavy weight on the emmc absorb some of the heat and so temperature setting should be higher?

Diah · 02-13-2023, 07:36 PM

Re: Hisense 58H6550E - Freezes/Won't turn on

you caused BGA issue on emmc. try again with yours heat gun.. but you need to load heavy weight on emmc to keep it much it can stick at boards during the heat process,

tmhobadcap · 02-13-2023, 06:42 PM

Re: Hisense 58H6550E - Freezes/Won't turn on

Thanks for your suggestions and advice.

I have tried Diah's suggestion first using the hairdryer, but the tv still freezes after turning on.

Then I tried the reflowing using hot air station. I set the temperature to 375 degree celsius because in my past experience I need to set to this temperature in order to remove leds from the led strips. After that, when turning on, I only get the Hisense logo appears for a few seconds as in the video https://www.youtube.com/shorts/xohI-g_V-vM. Did I set the temperature too high and damaged the chip? Or should I try higher temperature?

Diah · 02-13-2023, 10:31 AM

Re: Hisense 58H6550E - Freezes/Won't turn on

use hairdryer to warm up the emmc.. warm to hot Temp will make him servent for you.. no freez... then log in service menu ( not normal user menu ) and from there look after "Clear Chip" this is hard reset. hope it will help.