Proview rx-276 2600

[Snype32]

I have recently acquired a proview rx-276 from our local dump. It powers on and the screen flashes for a second, and goes out. Green led stays on. Caps all appear to be good, but I replaced the caps indicated here: http://blog.coppelltvrepair.com/2011...-power-on.html

Power supply seems to be putting out 12v contunious and 24v switched on a different connector. Is this right? I thought it was supposed to put out 24 on both connectors. Any help would be greatly appreciated. The power supply in question seems to be exactly the same as the one in this thread: https://www.badcaps.net/forum/showthread.php?t=23501

[smason]

Re: Proview rx-276 2600

Check the BL_On signal on the inverter board. If it's on, and the backlights shut off, it's likely the inverter sensing a bad ccfl, or a problem on the inverter board like a bad transformer.

[Snype32]

Re: Proview rx-276 2600

Thanks for the reply... What am I looking for on Bl_On?

Thanks!

[budm]

Re: Proview rx-276 2600

>3VDC = Backlights on, <1v = off

[Snype32]

Re: Proview rx-276 2600

Ok so I finally got around to checking what I think is BL_on. I could not find any label indicating it, but there is a pair (yellow and white) that is the only wires seperate from the power supply. I get over 4 volts across the pair, so that means the backlight should be on? The lights do flash for a second, then go out. I am getting 24 volts to the inverter across all of the red and blacks. It seems like it should be working. Any ideas?

Thanks!

[tom66]

Re: Proview rx-276 2600

Do the yellow/white go to the inverter? You should test from yellow to chassis, and white to chassis.

One wire will be backlight on/off, the other will be brightness.

[Snype32]

Re: Proview rx-276 2600

Thanks for the quick reply... Yes the yellow and white both come from the inverter. They are both in a connector. At the inverter, I get 4.8 on the yellow, .05 on white.


How can I tell which one is brightness vs bl_on?

Thanks for all the help so far!

This may be a stupid question, but is there any way it could be just the brightness turned all the way down? Can I apply a couple volts to the white and get the backlight on enought to see the menu? That would be too easy.

[tom66]

Re: Proview rx-276 2600

Unfortunately, you can't easily tell which is brightness and which is on/off. Do they change state when you press the power button? I know some TVs leave the brightness control fixed and then vary the on/off signal.

If you have two AA batteries and a battery holder, it is quite easy to control the on/off signal.

[Snype32]

Re: Proview rx-276 2600

The yellow is 0 on off and 4.8 when on.
The white is 1.2 when off and 0 when on.

[tom66]

Re: Proview rx-276 2600

OK it looks like yellow is on/off, and white is inverted brightness (0V = max brightness.) I have seen an inverted brightness signal before.

Can you post an image of your inverter board? The fault is most likely on there.

[Snype32]

Re: Proview rx-276 2600

Here you go:

[tom66]

Re: Proview rx-276 2600

This is a Darfon inverter; the transformers are very common failures.

How to test:
1. Unplug the TV.
2. Test resistance between red marks using the 20k ohm range. Note this down.
3. Test resistance between blue marks using the 20k ohm range. Note this down.
4. Test each set of two transformers like this; note the red and blue alternate. For the last transformer, test it as just the first transformer of the group.
5. Report the readings in this thread.

[Snype32]

Re: Proview rx-276 2600

Here are the results. The ones that are open did show a number for a second, then went open. I'm not sure if it's my meter or what.

Thanks for the help

[tom66]

Re: Proview rx-276 2600

Something's not right here. Did you use the 20k ohm range? All but one winding should measure virtually the same. The failed winding is the one which significantly differs. Also make sure the value on your meter settles before reading it off.

[Snype32]

Re: Proview rx-276 2600

I did let it settle. Maybe I am not measuring the right leads?

[tom66]

Re: Proview rx-276 2600

Can you show which range your meter was set on by taking a photo of it in that setting.
Also touch the probes, does the meter read nearly or exactly zero?

[Snype32]

Re: Proview rx-276 2600

When I tested them acorrding to this site:

http://www.lcdparts.net/Transformer3D.aspx

All show .95 except 1 that is open

[Snype32]

Re: Proview rx-276 2600

Here you go...

and yes it shows .0.. when leads are together

[tom66]

Re: Proview rx-276 2600

Hmm maybe I'm not understanding how this board works, it happens. Try testing across red and blue for each to see if the results are more consistent. So red and then opposite blue, for the top and then for the bottom, for each transformer.

[Snype32]

Re: Proview rx-276 2600

so on these leads? If so, all except 1 are .95. One of them is open