Ctouch cla-65fhda1

[JackDaniels]

Hi everyone,

Currently I'm trying to repair a CTOUCH CLA-65FHDA1 interactive touchscreen, it's like an interactive schoolboard actually.
I'm not finding much information about this screen.

This is what I tried so far:
Standby light when plugged into AC is on (red)
Screen switches on with remote, stby led turns from red to blue.
Backlights light up very briefly (less than 1 second)
With a flashlight close to the screen I can see that there actually is some image being displayed (video/main logic board seems to be working, I suppose)
Power board is delivering DC power towards inverter board, around 24V if I remember correctly.

So far my troubleshooting suggests the inverter board (DARFON v351-701) or the LED backlights themselves need replacing.
How can I be sure, what is the output voltage of this inverter board?
I can't even seem to find any specs about this board.
Only thing I found so far is this:

https://forums.arcade-museum.com/thr...87f3-a.447312/

As I cannot seem to find a replacement inverter board, there might exist another compatible one ?


Thanks in advance.

[nomoresonys]

Re: Ctouch cla-65fhda1

Unlike a CCFL, LED backlights don't require high ac voltages so they don't need an inverter. More than likely a backlight issue.

[nomoresonys]

Re: Ctouch cla-65fhda1

Quote "Backlights light up very briefly (less than 1 second)" Classic backlight issue symptom.

[lotas]

Re: Ctouch cla-65fhda1

Unlike a CCFL, LED backlights don't require high ac voltages so they don't need an inverter. More than likely a backlight issue.

An inverter also happens in led TVs (which converts from 24v to a higher voltage to power all the LED lines).

[nomoresonys]

Re: Ctouch cla-65fhda1

was referring to the separate much higher voltage inverters that ccfl tvs have.

[JackDaniels]

Re: Ctouch cla-65fhda1

Goodmorning,

I came across this youtube clip:
https://www.youtube.com/watch?v=rNqRZ2qaDJY

This guy uses five 9V batteries across a 100 ohms resistor to test the ledstrips individually. As the connector on my inverter board is similar, I thought of doing this simple test as well.
On my connector there are four pairs of red/black wires, which suggests 4 ledstrips in total. But are they connected in series with each other, like in the video, I will have to check...

Anyway, like this I can be check that either inverter and/or ledstrip(s) are defective.

Also, I sent an email to the manufacturer (CTOUCH) to provide me with further information on where to order the inverter board and or ledstrip(s).
If they're willing to share that information with me, I don't know...

At this point knowing for sure that the backlight is indeed with leds and not CCFL, I can only make an educated guess that the output voltage of the inverter should be several hundred volts and not thousands like on CCFL's.
Assuming that the ledstrips are indeed connected in series with each other.

I will keep posting updates as I continue with troubleshooting.

Thanks in advance for any further advice or tips on this issue.

[JackDaniels]

Re: Ctouch cla-65fhda1

My inverter looks quite similar, I will take a picture and post it when I can.
Only, my inverter has four transformers, and two connectors in total. One for the input voltages and one connector towards the ledstrips. On this output connector there are four pairs of red/black wires. This suggests 4 ledstrips.

[JackDaniels]

Re: Ctouch cla-65fhda1

An inverter also happens in led TVs (which converts from 24v to a higher voltage to power all the LED lines).

The attached picture lotas posted looks very similar to my inverter.
Only, mine has four transformers and two connectors in total, one for the input voltages and the other for the outputs towards the ledstrips. What are the output voltages for the one you posted lotas? Can you tell me?
Thanks in advance.