Glimmie
09-29-08, 01:56 PM
I have sucessfully modified a JVC HM-DH5U DVHS VTR for HDSDI. The HDMI port on this machine reports it's self as a computer signal and forces 4x3 aspect - at least on the three monitors I tested. So enough of this HDMI !@#$.
This mod was not too painful as the data busses are formatted with TRS. This is using a new National serilizer chip that has just about everything built in. That is the PLL and cable driver making the layout pretty simple. If TRS was missing I would have needed an FPGA in line to add that back as well as access to H&V sync pulses. I plan to take my whole HT to an HDSDI core feeding a DVDO VP50pro. I'll post more mods as I complete them.
I used a Tektronix TDS540 sampling scope, 24 channel 500mhz logic analyzer, and a special home grown DVHS test tape to generate specific bit patterns so I could untangle the 20 bit video data buss. In this machine, the HDMI chip is driven off a seperate bufffer from the DACs so you can't just short out bits and see what happens to the analog component output image. And with HDMI connected, any loss of a single data bit shuts the transmitter chip down so no "short circuit testing" there. The DAC is a proprietary JVC chip and is BGA to boot! I can encode DVHS tapes at work so that was a big help. The EYE pattern was shot off a Tektronix WFM700 scope at work. I direct fed it through a 25 foot 1694A cable.
I hacked the Silicon Image HDMI transmitter chip pinout - well at least enough of it to do this. They will not release the full datasheet without a license which is $10K per year. The sales brochure does provide ay least a rough internal block. The HDMI chip pins were all covered with hot glue beads. A heat gun and patience got it off. I guess this is JVC'c idea of HDCP compliance - not very effective as hot glue basically sticks to nothing. Also note the covered pins on the microcontroller. This is probably something to do with the DTheater format.
The mod:
http://usera.Imagecave.com/adelle/DSCF0220.JPG
My DAC for testing:
http://usera.ImageCave.com/adelle/DSCF0216.JPG
Bare board before components mounted:
http://usera.ImageCave.com/adelle/DSCF0213.JPG.jpg
EYE pattern:
http://usera.ImageCave.com/adelle/DSCF0229.JPG
Eye pattern is quite good if you know how to read this waveform.
This mod was not too painful as the data busses are formatted with TRS. This is using a new National serilizer chip that has just about everything built in. That is the PLL and cable driver making the layout pretty simple. If TRS was missing I would have needed an FPGA in line to add that back as well as access to H&V sync pulses. I plan to take my whole HT to an HDSDI core feeding a DVDO VP50pro. I'll post more mods as I complete them.
I used a Tektronix TDS540 sampling scope, 24 channel 500mhz logic analyzer, and a special home grown DVHS test tape to generate specific bit patterns so I could untangle the 20 bit video data buss. In this machine, the HDMI chip is driven off a seperate bufffer from the DACs so you can't just short out bits and see what happens to the analog component output image. And with HDMI connected, any loss of a single data bit shuts the transmitter chip down so no "short circuit testing" there. The DAC is a proprietary JVC chip and is BGA to boot! I can encode DVHS tapes at work so that was a big help. The EYE pattern was shot off a Tektronix WFM700 scope at work. I direct fed it through a 25 foot 1694A cable.
I hacked the Silicon Image HDMI transmitter chip pinout - well at least enough of it to do this. They will not release the full datasheet without a license which is $10K per year. The sales brochure does provide ay least a rough internal block. The HDMI chip pins were all covered with hot glue beads. A heat gun and patience got it off. I guess this is JVC'c idea of HDCP compliance - not very effective as hot glue basically sticks to nothing. Also note the covered pins on the microcontroller. This is probably something to do with the DTheater format.
The mod:
http://usera.Imagecave.com/adelle/DSCF0220.JPG
My DAC for testing:
http://usera.ImageCave.com/adelle/DSCF0216.JPG
Bare board before components mounted:
http://usera.ImageCave.com/adelle/DSCF0213.JPG.jpg
EYE pattern:
http://usera.ImageCave.com/adelle/DSCF0229.JPG
Eye pattern is quite good if you know how to read this waveform.