hitachi 32HXC01U backlight

[ozy]

got a hitachi 32HXC01U (17pw19-5 psu )and the backlight turns off after a few minutes. Checked the usual diodes and mosfet all check out ok.
could it be a failed led in the panel ? or would that cause no backlight at all ?

[sordids999]

Re: hitachi 32HXC01U backlight

Posting pictures of the back of your tv showing the boards with clear pictures may help you more with fixing your problem

[ozy]

Re: hitachi 32HXC01U backlight

as requested,

[sordids999]

Re: hitachi 32HXC01U backlight

On the connecter on the psu which goes to the backlights are the voltages staying steady or slowly dropping ?

[ReeceyBurger123]

Re: hitachi 32HXC01U backlight

Ive had the connectors that link the leds fail intermittently, watch my vid and skip to the part where I bridge them:

https://m.youtube.com/watch?v=RxwdC7V5Ue0

[ozy]

Re: hitachi 32HXC01U backlight

when the leds fire I get 69v when they go out the voltage slowly decays to 0

[ReeceyBurger123]

Re: hitachi 32HXC01U backlight

Right as it goes to 0 your Psu is faulty, if the Leds were the fault the voltage would go from 60 to 24v which is un-boosted. Now can you please heat the Psu and see if the fault occurs faster.

[ozy]

Re: hitachi 32HXC01U backlight

just rechecked at the plug, when leds are on the black wire has about 85v and red has about 32v, when led shut down black wire decays to 24v and red decays to 0v.

if there is no video source the backlights illuminate for a few minutes at low brightness, if i connect a video source backlight lights at full brightness for a few seconds then shuts off.

[ReeceyBurger123]

Re: hitachi 32HXC01U backlight

Right ok, might be best try heating the Psu see if it cuts off quicker. However as the 24v remains its not a feedback issue turning off the 24v rail. Could be an Led driver Ic fault though but we can test that after we see if the Psu is causing that.

However my best is the connections in the panel as you said the return (red wire) drops to 0v so could be connection issue with the strings.

[Alastair E]

Re: hitachi 32HXC01U backlight

Ive sometimes found a dead LED does this--They go intermittent.

I tack a similar numbered LED strip across/in place of each strip in turn till it works, then bridge each LED on the faulty strip in turn till it works/stays on.
--When it does you found the dead one.

A tedious repair, sometimes much potching about, but not hard to do.

[ozy]

Re: hitachi 32HXC01U backlight

Heating psu makes no difference, is looking like led fault.
Already changed the mp3394 control chip after I slipped with the probe earlier so I know that's ok.