Re: Hanns-G HG281D, LCD Monitor no power
Another problem strikes, I have replace the psu with an universal one and now the HDMI input is not working, I get a message on the screen that no input is detected an the digital one,but the VGA input is working.
CATA2003
Member
Last Activity: 10-11-2015, 03:44 AM
Joined: 12-30-2013
Location: CJ
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Re: Hanns-G HG281D, LCD Monitor no power
1. They are on the PSU board (on the feedback chain)
2. SMD
3. Don't have them (have been replaced with other value, now I will make it as the original one)....Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Can someone provide me the values of R128 and R124?Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Does anyone read what I'm writing???? It was powered from a laboratory power supply! And to be more exact It's a Fluke Scopometer powered from battery. Yes I'm an engineer, I know how to work with it. Anyway with the new opto it engages power for the IC....
Yes 1.2Mhz, I didn't say that the signal looks good, but it is from 0.74 to 1.2Mhz, so I'm telling that the IC is toasted.
Anyway thanks, I will change it and hope it will start....Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
I have replaced all 3 opto, they were cooked (the board has discoloration under and near them). The were replaced with the same part number Sharp PC817.
Taking into account that the 5V std-by and the PS-on are working it means that the opto's are ok. I looked at oscilloscope waveform and now it's runing at almost 1.2Mhz (the IC for the 24/12V was powered from a laboratory power supply 13V without the high voltage to the Fets/PFC, only power to the IC.).
So I guess that I need to replace it, maybe the 16V were...Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
It's L6598, Like I said.....it was only the power supply , and a 12V 40W bulb....Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Yes it was started with a resistor, main disconnected (caps replaced on the main) the problem is with the higher voltage applied to the resonant controller , 16V instead of 13-14V.......Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
So today I recapped all the capacitors form the power board excluding those from underneath of the heat-sink (near the PFC Choke). So now I have 5Vstd-By with no ripple, but then I tried to start the main power supply It won't start. After that I replaced the optocoupler, now It tries to power, I measured 16V and 36V instead of 12V and 24V. The 5V rail seems to be stabile but it comes from a buck converter.....so it has it's own feedback..... I have also find that the power to the resonant controller is 16V from datasheet this is too much.Now...Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Ok, so the PSUON should be pulled to the 5V STD-By?
This week I will replace all the capacitors....Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Dude, those capacitors are for the logic board, I asked about the PSON???
Meanwhile I repaired the std-by power, not it has 4.99V.
For the moment I have some improvement, the led is powering from blue to yellow.
I see that seccond power supply it doesn't start, so I asking is the middle octocoupler responsable for the power Up?
I see that the octocoupler led has around 1.2V and on the fototransistor 22-27V
Also on the capacitors C83-80 I have 3.3V and 2.2(off)and 1.8V (on state), I guess...Leave a comment:
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Re: Hanns-G HG281D, LCD Monitor no power
Hello,
I have also a problem with this monitor, for the moment I didn't replace the capacitors, The 5V Stb By is working.
How can I turn on the PSU without the other board? Connect the PSUON to the 5v std-by? Also the q601 seems to be very toasted but the junction diode is ok, i would replace it, but I don't know it's part number. Can someone tell me an alternative to that? Also without any connector, and the mains ON on the middle octocoupler (hot side) I have 22V, I guess that one is responsible for start-up ? (With 5v on...Leave a comment:
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