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DVI port

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2PAC Mafia

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Hi guys,

I have an industrial PC to be repaired which seems to have problems at DVI port. If I don´t connect anything on it and I measure with the scope should I have signals? if so, which ones?

Thanks, regards.
 

ronsimpson

Well-Known Member
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C4- Analog Horz Sync should have a signal.
8 Analog Vert. Sync also.
14 +5V power.
6,7 should have a resistor pulling them up to 3.3V or 5V.
upload_2018-3-9_10-0-55.jpeg
BUT!!
Windows is complicated. The PC should send +5V to the monitor. Then the PC will talk to the monitor over pins 6, 7. At that point the PC will know what type of monitor and what resolution. (only then can the PC know what H. and V. sync frequency the monitor can use)
There is a good chance the PC might not send any video signals until all this works.

All the TMDS signals have a very small signal when working. So only the H and V Syncs will have something you can see simply. The DDC clock and Data are TTL type but will probably not have data if there is no monitor.
 

2PAC Mafia

Member
OK, understood, thanks. I´ve seen a chip http://www.amazingic.com/chinese/01_products/AZC209-07P near the connector. First I´ll scope outputs directly at connector and then I will go deeper in the chip. I don´t know which operating system is using this unit. Monitor connected was Hatteland and also with problems so I don´t know which damaged the other...
 

gophert

Well-Known Member
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If the monitor is not taking back to the video card after the video card sends the 5v communication signal, the card will not try to send a video signal.
 

unclejed613

Well-Known Member
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OK, understood, thanks. I´ve seen a chip http://www.amazingic.com/chinese/01_products/AZC209-07P near the connector. First I´ll scope outputs directly at connector and then I will go deeper in the chip. I don´t know which operating system is using this unit. Monitor connected was Hatteland and also with problems so I don´t know which damaged the other...
that chip is an ESD protection device. check to see that none of the signal pins on it are shorted to ground or Vcc. there are 3 VCC pins, and one GND pin.
 

2PAC Mafia

Member
Thank you, but finally they decided to buy a new one so I couldn´t continue with the troubleshooting.
 

gophert

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Most Helpful Member
... they decided to buy a new one
That might explain why the TV repair shops in my city have all gone out of business (about 25 years ago).
 

atferrari

Well-Known Member
That might explain why the TV repair shops in my city have all gone out of business (about 25 years ago).
Not TV but monitors, there was an electronic engineer who dedicated only to them and did the repairs so quickly that his main concern was customers picking up the ready ones in time to avoid cluttering the space in the workshop.

Once, a maritime agency, as per my reccomendations called him on board of a vessel berthed in Bs Aires. In less than one day repaired the defective one but two other defunct pieces of marine equipment in the bridge. Happy Captain after that.

It seemed he had well solved the access to spare parts. The last time I met him he was well up to speed with LCDs.
 
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