Caravan 15 inch TV Turns on but keeps re-booting - Page 1
Forum section: electronics / repair

author: jonovid
author_rank: Super Contributor
timestamp: May 15, 2022, 04:03:57 pm
content: brand GVA. model GVALEDJ15 15.6 HD LED TVred LED is the normal standby mode. when I normaly power up the 15 inch television with the remote, the red standby LED changes to green and in 2 seconds the input menu will show on the screen. this is normal.however an odd re-boot fault has appeared after not been in use for a year. otherwise had very little use as a spare television.the red LED is the normal standby mode. when I now power up the TV with the remote, the red standby LED changes to green and in 2 seconds starts switching cycling between red and green in one second changes.also the TV remote and all other buttons fail to work. the TV screen shows the GVA logo but will Not change to the input menu.I have no choice but to remove the power from the TV at the AC power adapter. as all buttons including the TV remote, are bricked by this re-boot fault.is this corrupted firmware? or a common fault for this type of TV? does anyone know if this is a common known fault? like a bad electrolytic capacitors?or is this a case of beyond economic repair as any replacement pcb would cost more then the TV itself.I am unable to find a schematic diagram for the pcb. so without knowing the pcb voltages I am lost.here is an image of it. any suggestions? the GVA 12volt 15 inch LED television cost $100 (on sale) in 2017.GVA 15 inch LED television model GVALEDJ15 user manual.https://gvaproducts.com.au/uploads/GVA15GLED-15.6%E2%80%B3HD-LED-LCD-TV.pdfI need repair and service information.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 15, 2022, 04:59:37 pm
content: Check my topic here:https://www.eevblog.com/forum/repair/(solved)-hungchang-lcdled-tv-boot-loop-repair/msg3775598/Same manufacturer, different model, could give you some ideas.

author: David_AVD
author_rank: Super Contributor
timestamp: May 15, 2022, 10:52:17 pm
content: Are you sure that the power supply is not buckling under load as it starts up?

author: jonovid
author_rank: Super Contributor
timestamp: May 16, 2022, 12:00:06 am
content: I will investegate your suggestions more, befor considering abandoning the project to the scrap bin.GVA15GLED is not GVALEDJ15as I am a lazy individual with more then one weekend project on the go at a time . I will get back to you in time.probing pcb voltages on boot/start up would seem like a good place to start. maybe.blow air, tapping, wriggling and look for dry joints or bad electrical contacts. also.a model GVALEDJ15 schematic diagram would help .if anyone knows. thank you for your suggestions.

author: james_s
author_rank: Super Contributor
timestamp: May 16, 2022, 12:02:47 am
content: Capacitors are the first thing I'd suspect for a problem like that, especially with those surface mount electrolytics, those are notorious for failing.

author: strawberry
author_rank: Super Contributor
timestamp: May 16, 2022, 06:57:16 am
content: failed ROMlooks like some laptop/desktop monitor panelwith something like this LVDS control board :https://www.aliexpress.com/item/32892182589.html

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 16, 2022, 11:09:03 am
content: Quote from: strawberry on May 16, 2022, 06:57:16 amWhile a corrupt firmware or even bad option configuration data can caue boot loops by linking to my repair report on a similar model I was trying to show that it is not always the case.Checking power supply voltages right down to the CPU supply is a wiser first step in troubleshooting than assuming the unobtainable firmware is corrupt and having a good excuse to throw the thing away.About the SMD elecyrolytics: There were a lot of catastrophic failures on equipment built in the 90's using them, since I've seen very few fail and when they have it has always been where ripple current is high. (Switching regulators, class D audio amps.)I'd check the elecyrolytics on the main power supply and be more suspicious of LDO regulators being a little low on voltage than SMD elecyrolytics.