Re: After a good DAC

I switched from my onboard dac to the NUforce uDAC3. Due to a ground plane issue with my board causing horrendous noise whenever a usb device was connected.

Im reasonably happy with it and it seems to meet your specs might be another option to consider.

[url]https://www.optoma.co.uk/audioproduct/udac3[/url]Re: After a good DAC<br /> <br /> ...asonably happy

Re: LG 42la620v Backlight Issue

Im getting roughly 35 to 50 volts on both led strings the refresh rate of my meter isnt very fast so there is variation between readings. This happens regardless of whether I have the leds plugged into there connector.

I know that between 70 and 105 vdc @ 0.313A is nominal for this board.

Re: LG 42la620v Backlight Issue

I got a schematic from:

The driver uses the BD9483f IC if anyone knows about it.

All Caps tested good on the psu so ill go into more depth with it tomorrow with the schematic.

I can buy a good psu board on ebay I can also get a new driver ic if i can isolate it as the cause of the fault.

Re: LG 42la620v Backlight Issue

How would I go about diagnosing a fault with the back light led array not the driver?

In my experience leds usually fail open circuit and there seems to be very even illumination across the panel when the back light is running.

This leads me to believe the driver is at fault and failing under load.

I have not disassembled the panel to that point yet but I assume that the diffuser may hide individual led failures.

Browsing parts available I cannot see any additional led driver board so I...

Re: LG 42la620v Backlight Issue

I tried manually jumpering the PWR_ON and DRV_ON pins to be high. This resulted in the 12 and 24v rails of the psu becoming active but still no output from the back light driver regardless of any load attached.

Re: LG 42la620v Backlight Issue

If the back lights are faulty why do they function for a split second on startup is there any general resistance that I should see across the led arrays.

Also will the back light driver shutdown if it detects no load?

I cant really disconnect the psu from the logic board as its relying on PWR_ON and DRV_ON pins staying high. I can try manually jumpering these pins too be brought high all the time and see what that does.

I have a LG 42la620v tv with a back light issue. The set powers up as normal displaying the splash screen with the back light working properly but the back light cuts out after a second and the power led flashes three times. The logic board is functioning a picture can be seen and functionality confirmed by holding a flashlight up to the screen.

I have measured voltages from the PSU and the 3.5 12 and 24v rails all measure correctly and have little to no ripple or transients as measured with a scope. The model of the PSU is EAX64905401(1.7) I can post pictures if needed.
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Re: New Members - please post your introductions here

want to ask a question