Re: Toshiba LCD 22BL502B Solid Green Led No Picture
The glass forming part of the actual LCD display. How important is that ? Minor crack. Is this just to protect internals or does the glass actually play a part in image generation. Something about substrate with electrodes.
Thanks.
tanz0
Member
Last Activity: 04-21-2016, 09:41 AM
Joined: 11-04-2013
Location: Belfast
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
I think those are the outputs. The other connector is a 6-pin which the screen currently has for a backlight connector. Would you need 5 parallel 24v inputs and separate GNDs ?
I did notice the 24v but I thought might auto-adjust or assumed it was for 24v. I think you mentioned at the start this model operated on 12v/24v.
Thanks.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Link !
[url]http://www.iccfl.com/product_info.php?products_id=16181[/url]Re: Toshiba LCD 22BL502B Solid Green...id=16181[/url]Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Thanks.
I understand what you're saying however there is another item here, which is apparently a direct replacement for the screen in question, although I haven't managed to see any part such as this on the assembly. Anyway it has 5 pairs of GND/VCC connections, which I'm assuming are in parallel ? Unless the circuit is performing the current adjustment you speak of.
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Link to driver btw:
[url]http://uk.farnell.com/midas/ledv1/led-backlight-driver-for-small/dp/2219006[/url]Re: Toshiba LCD 22BL502B Solid Green.../2219006[/url]Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Having great difficulty trying to get a datasheet for this screen.
I have managed to find an external led driver that looks suitable to drive backlight off existing 12.45v, however it has 4 connections, including DIMMER control and standby.
The backlight connection on the LC216EXN has 6 pins, I'm wondering do you know what these are for. As previously mentioned, they at labelled COM , CH1-4 and I assume GND.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Ah, cheers thanks. Just to reiterate though, I see no picture on screen at all in bright light, you're convinced that this is the only problem with the t-con board ?
Thanks.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Think that's bd926-1efv
Rohm led driver apparently. What are the common problems that develop with boost controller ? Caps burn out ? You could do a hot air rework of the chip ?
Thanks.Last edited by tanz0; 11-12-2013, 06:51 AM.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
I see 4 small components adjacent to the chip. Do these boost converters use external caps for charge pumps ? Will try an find out, those model numbers return no results. Even trying to see the model numbers with a magnifying glass is difficult. And I have 20/20 vision, apparently.
Thanks. In the event of this chip itself gone, I take it that it is game over, how could you swap this component out, hot air soldering iron ? Caps look potentially feasible.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Hi looks like b0926-1efv. Also has 130-ht4 on it.
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Hi, which chip do you mean ? There are 3 in the vicinity.
One square to the left, looks around 40 pins or so. One rectangular above, 8 pin. And one rectangular to the right, around 20 pin.
Square one looks like OISWL-0058A. I could be a one of course.
8 pin looks like st 404rp ?
Thanks.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Hello, I have tested fuse, there is a steady 12.45v across both ends so I don't think this is the problem.
Can anyone tell me what the correct voltages should be for backlight connection. I have com, and ch1-4 marked on board.
12.45v between com and chassis, 3.3v on ch1-4.
Does this look like a backlight problem ? I can see absolutely no picture when it is on during day in bright sunlight.
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Re: New Members - please post your introductions here
bad caps bad caps, what you gonna do, what you gonna do when they blow on you ?
:-)Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
I did yeh, I was speculating though the wire could have fused at some point along the coil, which would fail closed circuit, but would alter inductance. In any case it's prob unlikely this would cause total blackout.
I'll need to test the fuse when it's in operation.
Cheers.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
One more thing. Finding it difficult to test these parts since they need to be grounded on the chassis to operate correctly. However the chassis prevents access to the t-con board and the cables aren't quite long enough to reach when chassis is moved elsewhere. Do the boards generally have a ground line soldered to them each, both power supply and mainboard, when being tested.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Thanks. Jumping back to the inductor problem speculation previously discussed, it's noticeable that the T-con protective cover has a small window cut out for just these two inductors. Precisely the correct size for inspection and or heat dissipation. I'm wondering then are these components prone to fault. I've seen others speculating about faulty inductors here but there seems to be a consensus they are rarely the culprit.
I intend to borrow a meter and measure inductance directly.
Thanks.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
I read somewhere here that it is possible for a T-CON fuse to be defective, but still pass current, just during operation the resistance increases until the board fails to operate, instantaneously of course. Is this true ? Also hear some discussion around using 'ice spray' to diagnose bad components ?Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Hello, just wondering how, if at all, can the led driver board be replaced, the various ribbon cables seem to be attached to both board and screen. Although I do see led driver modules on eBay.
Michael.Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
You'll have to forgive me I've seen this term 'T-con' used a lot but not entirely sure what this is. Is this the LED driver board, in which case yes this is the board the inductors are on.
The inductors are reading 3k and then quickly dropping to 0. Both of them have same behaviour though so it's unlikely this is problem. They do look somewhat burnt though. Any way of verifying exactly what problem is. Where would be a valid test point on driver board to check the current is getting past this point in circuit. ...Leave a comment:
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Re: Toshiba LCD 22BL502B Solid Green Led No Picture
Should they measure 0 instantaneously though ?Leave a comment:
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