Hyundai HLT-2001B schematics

[Learn2Day]

Hi.

I have a busted Hyundai LCD TV (completely dead, no leds, nothing) offered for me to repair and use in my bedroom.
I assume the issue is in the power board cuz i have no Vdc outputs and i hear some clicks near the transformer, but i need the schematics to make sure it's not a power switch issue, follow the voltages, etc..
Some pics attached below.

Can anyone help? Cheers.

[tom66]

Re: Hyundai HLT-2001B schematics

There is a bulging cap on the power supply: probably not causing the issue but should be replaced.
No VDC on -any- pin? Not a power switch issue.
Clicking PSU: check output diodes, startup capacitor, unplug main board and check if outputs appear then.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Hi,

Diodes seem fine, startup capacitor also outputs 230Vdc, still no outputs, i get oscillating voltages, 0.2~1.5V in 5V and 0.1~0.4V in 12V.

Can you please help with some more measure points? Thanks.

[tom66]

Re: Hyundai HLT-2001B schematics

Where do you measure 230VDC? Do you mean 23.0V DC?

[budm]

Re: Hyundai HLT-2001B schematics

If the power supply is ticking/or the output is fluctuating, it can be due to bad start up caps, or shorted load which will cause the power supply to be in the start-up/shutdown loop. Since the board also has the inverter circuits, you should also check the MOSFEs (4 of them on the bottom side of the board) which drive the inverter transformers for shorts.
230Vdc measured right at the two legs of the black main filter cap? That does not sound like the correct voltage if that is the case.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

I've re-measured the big black startup capacitor, and i get 312Vdc (????) between 2 pins, and get 212Vdc between + and GND.

If possible i'd like some help in how to measure/test MOSFETs and the same for inverters plus how to identify an inverter. I know the inverter piece on a laptop screen, but on a TV this is all new to me.

Thanks.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Hello again,


Guys, as assumed in link above, I've finally found the schematics for the power board, and followed the schematics. Oddly i do get 312V from BD101 + to - and so on until T1. I read 312V in 2 pins of transformer primary, and get virtually 0V (0~1V) in all secondary pins.. Also worth mentioning in one of those 2 primary pins (the one connected to D101) i can read a millisecond voltage oscillation exactly synced with the transformer clicks. It almost seems like a very very quick on/off. Same oscillation occurs in 2 pins of secondary, but only from
0~0.05V

At this time I'm doubting the issue is the transformer, and although I'm inclined to a faulty Q101, i need your help doing the proper tests before de-soldering it.

Please help. Thanks.

[tom66]

Re: Hyundai HLT-2001B schematics

Faulty Q101 would not cause this fault.
So you have verified the following diodes as not shorted? D102, D205, D206, D207, ZD207?
Also, check resistance across C301.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Hello again,

After much removing components and testing I think i finally found the short.
I was having a short at D205 and D207, thought that was it, but after removing short was still there. Removed D206, same thing. After this i used multimeter short function to test R202 and 203, they were fine..
I finally found the short in either or both R204 and 205. These resistors are SMD and before i replace i'd like to be sure I'm right. Considering I've removed D205,206,207, and that i don't get a short on R202,203, is it safe to assume the issue is in R204,205?

Thanks.

[tom66]

Re: Hyundai HLT-2001B schematics

R204,R205 form part of snubber around D206.
They should measure 10 ohm in parallel.
The more likely failure is both of C204 and C205, as ceramic capacitors can fail shorted, resistors nearly never fail shorted.

[budm]

Re: Hyundai HLT-2001B schematics

Lift one end of these two jumper to see if the shorts go away, these two jumpers feed the voltage to the inverter circuit. C301 is also bad (bulging top).
Alos post straight shot pictures of the bottom and top side of the board. P/N of those 4 SMD MOSFETs?

[Learn2Day]

Re: Hyundai HLT-2001B schematics

You're right, R204,205 do read 10ohm, but neither C203,204,205,206 reads shorted.
I can't read them in my multimeter, dunno why, even in 2n (lowest available) i read .001, in short function they're all open.

Something else i forgot to mention earlier, this board doesn't have a ZD207, there's a factory blank space in it.

I also read a short in C223,224,226, but none in C214,215. I had previously removed C224,226 to remove D205,206,207, and when i measured they seemed fine.. Should i remove and test them all again, or do you think we should follow to inverter circuit?

Thanks for all your help so far.. I'm a bit lost here, but without all your help I'd be completely doomed! Once again, thank you!

Cheers.

[budm]

Re: Hyundai HLT-2001B schematics

Lift one end of those two jumpers to isolate the inverter circuit from the power supply section to see if the power supply will work again.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Oh my god!!!

Removed C301, jumper 367, C223,224,226, and the short is still there!!!

SMD Mosfets P/N, according to schematics are AO4606, and i confirms on the magnifying glass, 4606 BA6Y12.

I'll try to post some straight pics next.

Thanks.

[Learn2Day]

Re: Hyundai HLT-2001B schematics

Finally some results!! I've remove both jumpers instead of just one and now the short is gone. Gonna re-assemble the power circuit now, and I'll try to follow the jumpers circuit next. Any more tips?

Thanks.

[budm]

Re: Hyundai HLT-2001B schematics

OK, that is more like it, lift the end of BOTH jumpers. So the shorts are in the inverter circuit as I expected, which is more likely due to shorted MOSFET (shorted S and D pins).
AO4606:
https://cdn.badcaps-static.com/pdfs/...cccda0a27c.pdf

[Learn2Day]

Re: Hyundai HLT-2001B schematics

You're right! U301 is shorted from S to D. Gonna buy a replacement right away.

Thanks!

[Learn2Day]

Re: Hyundai HLT-2001B schematics

They're sold out! Damn! Can you help me find a compatible replacement datasheet?

Thanks.

[tom66]

Re: Hyundai HLT-2001B schematics

http://www.ebay.co.uk/itm/5pcs-AO460...item25632454af

?

Would also suggest you replace the capacitors.

[budm]

Re: Hyundai HLT-2001B schematics

You should replace all 4 at the same time when you find the replacement.