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ESD Diode on HDMI output of Yamaha a1050 RCVR

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    ESD Diode on HDMI output of Yamaha a1050 RCVR

    I lost one of the two hdmi outputs on a yamaha rx-a1050 receiver. Of course, it is the hdmi1 which has the arc capability which was useful. The second output hdmi works OK.

    I got an hdmi breakout board which gave me access to the "little guys" in the hdmi. I did some gross DC voltage measurements to ground and found that the Data1 pair (4 and 6) had a lower voltage than the working hdmi.... 1.1v versus 2.9. All others pins seem to be OK. Further when plugged into a display, there is no video but a message on the screen which I assume is the display's status for the link indicates "audio only". This would seem to indicate that perhaps the main hdmi transmitter chip is functioning "OK". I am thinking that perhaps the ESD diode pack on the data pair is "leaking" to ground causing a load on the pair. The ESD diode package is ESD7004mutag. I was wondering IF I remove the package (ie. de-solder... might still be tough to get that thing off without damage somewhere), is it safe to operate the unit temporarily for test purposes to see if it is indeed the issue. I haven't been successful in testing it in circuit as the component pads are very small and getting good probe contacts is difficult. Having said that, I am not sure that I see much / any difference between the pair in question and others (packages or the adjacent pair in the package)... but I am not sure that I am testing it correctly as it appears that it might be some form of zener maybe if I understand the spec.

    Any guidance on this? Thanks

    I guess the other question is checking to see if there is something happening on the pair. I have a little single channel hand held scope. Looking at the each individual pin of the pair to ground just shows the dc value. How is this tested to at least just see some "data waggle" to if anything is actually happening? My scope might not have enough bandwidth at 100mhz.... :-(

    Again thanks for any hints.

    Re: ESD Diode on HDMI output of Yamaha a1050 RCVR

    Well, I lifted the esd diode pack for the data0 and data1 pairs (in the same pack). No joy as the impedance to ground is still low (~6K) for either of the bad lines versus high mohm for the good lines. The only thing between the hdmi pins and the transmitter chip (256 pin) is some smd inductor pairs. I lifted the one involved. No change. It appears that the drivers involved in the data1 pair have an issue at the chip. I am not risking replacing the chip as one output is better than none... :-)