Hyundai HLT-2001B schematics

[Learn2Day]

Re: Hyundai HLT-2001B schematics

I've found an AO4606, but I've bought only one. Wasn't cheap either.. 2.60€ for one!

Dumb question from this noob.. Why should I replace all 4 if only one is busted?
Replacing the capacitors is affordable, but i see no point in spending 10€ in mosfets if one solves the problem.. I'm more interested in replacing the transformer, that's making an awful sound when i connect power (a sort of continuous "chhiiiiiiiii" lol).

Thanks.

[tom66]

Re: Hyundai HLT-2001B schematics

When one fails, it can damage the others in a non-obvious manner.
This means if you then put in the new transistor it blows it up so you waste more money.
Or the other transistors are "walking wounded" and work briefly before failure.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Ok. I'll buy 3 more tomorrow before replacing this one.

Tomorrow, after removing the 4 mosfets, I'll test it again for shorts and post back if any other issue appears. If not, I'll just post success!!

Thanks for all your help so far.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Hi guys.

Today i finally received all 4 mosfets and replaced them.
Now the TV finally turns on, but i have no back light! I pointed a lantern to the screen and i could clearly see the volume bar up and down as i went up or down, but i have no back light in any part of the screen. Can you guys help me?

Thanks again.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Dunno if this is important but i did noticed i read 12V on D301 and D304, but read 0V on D302 and D305. Could it be U303 is the issue?

After reading the datasheet it doesn't seem to be that.. I'm so confused.. Please help!!

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Additional info..

I have connected a CCFL lamp from a laptop screen to lamp connectors and get no output. Also tried to measure outputs but have no voltage.

Thanks.

[budm]

Re: Hyundai HLT-2001B schematics

Did you put the two jumpers back in place?

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Yes, of course! lol

[budm]

Re: Hyundai HLT-2001B schematics

So you are getting 0V at the jumpers? We had you lift the jumper to see if you will get all the voltages back in the earlier test. I am having a little hard time seeing "D301 and D304, but read 0V on D302 and D305" in the pictures.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

It's not in the pictures budm, it's tiny SMDs hard to see... I used the schematics (download in post #7) to follow the circuit. D301,302,304,305 are connected to U301,302 (AO4606 SMD mosfets) on the inverter circuit.
Actually it makes sense, cuz 3193 IC (U303) pins 8 and 9 connected to D302,305, initial state in pins 8,9 is "forced to GND level" accordind to it's datasheet.

Even although everything seems fine to me in U303, I'm fairly inexperienced in understanding and testing it, but considering this IC connects all 6 backlights I believe the issue is either here or BL/ADJ input that controls the IC and I have no idea where it comes from..



Thanks!

[budm]

Re: Hyundai HLT-2001B schematics

So you do have voltage now at the Jumppers? if that is the case then we need to find out if the logic board is sending the BL_ON and Dimming Control (BL_ADJ) to the inverter circuit or not. There should be ENABLE pin to turn on that PWM IC.
The BL_ON will be present when the monitor detects the video signal from the PC otherwise it will be in standby state.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Hi.

I do have 12V at those jumpers. I found a BL pin in logic board connector, and is connected to IC pin 13 through R315, but it's not giving any voltages differences either if TV is on or standby. I read 0.1V in both states.

I got a bit confused with your steps explanation... Should I use a video signal in VGA port?

Thanks.

[budm]

Re: Hyundai HLT-2001B schematics

OK, the logic board is not sending the BL_ON (>2V = ON) to turn the inverter. Yes, you do need to feed the it with video signal, I.E. VGA. The key point is that you should see the backlights flash on at least before it goes into standby. By the way, did anyone else work on this unit before you and did you see it work before it went out?

[Learn2Day]

Re: Hyundai HLT-2001B schematics

No, no one worked on this TV before. It was offered to me by a family friend after it got busted. Never opened before it got to me. Will try VGA and post back.

But my main concern now is.. Either VGA works or not, how do I follow and fix BL_ON signal?

Thanks.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

VGA is recognized by laptop but still no back light. Found schematics.


Thanks.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Well, this is weird.. After following the circuit on logic board, I assume BL is NOT BL_ON, is BL adjustment. I believe BL_ON actually refers to ON/OFF instead.

Weird thing is, ON/OFF has power and VDD on U303 (pin10) also 5V, and ON/OFF (pin6) reads 2.5V. By this, I think the issue is probably not in BKL ON/OFF.

This leaves BL Adjustment (pin13), on which i read 0.99V, but I read 0V in BL connector pin.

I dunno how i can adjust brightness in a dark screen. Brightness adjustment is in menu, and i can't see anything to navigate menu. It's getting worse and worse..

Please help. Thanks.

[budm]

Re: Hyundai HLT-2001B schematics

At 1V, the lamps should be on, the range of the lamp brightness is 0~5V (0 = min, 5 = Max). So the problem is in the inverter circuit some where.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Ok, i started to follow BRT_ADJ circuit on logic board. I believe i found a irregularity, but i don't where the issue is coming from..

I read 2.90V at IC500 pin28, but it drops to 0.78V in R521. All seems fine here, but problem is at Q502 i get 0V output to R526,527. R526 reads 5V in the other end. Already tested C538,540 for shorts but all seems fine.

Could it be a burned Q502? It's an SMD NPN transistor and unlikely to burn, but I'm about to believe anything..

Thanks.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

At 1V, the lamps should be on, the range of the lamp brightness is 0~5V (0 = min, 5 = Max). So the problem is in the inverter circuit some where.

Not really. Please consider I read 1V at pin13, not the connector.
For pin 13, datasheet says:

Low frequency PWM controlling input. A PWM output comes out by
comparing this DC input and the 1.0 ~ 2.5V triangle wave that is generated
by CTPWM.

By this i assume 1V is the minimum voltage which is always present. But I'm open to suggestions..

Thanks.

[budm]

Re: Hyundai HLT-2001B schematics

So what do you read at the connector? The DC control signal is used to adjust the PWM. The main point is that, the lamps should fire up first and if there is something wrong, the detection circuit will shut it down.
Sch page 3 PL500 pinout for the BL_ADJ.