"The" Onkyo TX-SR875 Thread - Page 203 - AVS | Home Theater Discussions And Reviews
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post #6061 of 6062 Old 02-26-2015, 01:04 AM
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has anyone ever tryed using the 4X I2S PCM/DSD audio stream inputs thats on the 10pin connector going from the HDMI board NAHDM-9114 to the DSP board NADSP-9072 ?
the 10 pin connector has the following names for each connection,

1. HDSPDIR (i think this is the digital S/PDIF from the SIL9135 an also go's to SIL9134)
2. GNDHD Ground
3. PCMLR/DSDFL (I2S data for main Left & Right/DSD front Left
4. PCMBCK/DSDCLK (I2S/DSD Clock Signal)
5. PCMLRCK/DSDFR (I2S LR Clock/DSD front Right)
6. PCMCSW/DSDSW (I2S Center+Sub/DSDsub
7. hdmi clk
8. hdmi rst (go's high to reset the hdmi mpu ?)
9. vsp rst
10. CEC IO (CEC in/out data ?)
11. vsp rxd/vsp scl
12. vsp txd/ vsp sda
13. hdmi stb
14 rx mute (think this go's high to mute the audio I2S input stream i am trying to get working from hdmi board ?)
15. hdmi sdi

now can anyone help me please ? what signal's out of them 15 do i need to work out in order to get the I2S buses working please, any ideas ?

if only we could get the 4X I2S and DSD audio input bus's working the TX-SR875 would be one hell of a DIY project

it look's possible to mod the power supply's to,

the DAC board from separate highly regulated pure noise free power source along with analog input board

it seem's there's also 3 separate secondary winding's on the transformer for the power output stage but they each pass through a rectifying diode then coupled all all together but could split that up using extra filtering cap's then change how the powe output stage is powered, may be split it up like 2 of the winding's powering 2 channel's each then the other powering 3

the DSP board also has what i think is a JTag connection so may be possible to try and work with the 3 DSP chip's and re-program them as digital Xovers then you could use the amp as a 3 way stereo amp leaving a channel for sub making a basic 4 way with stereo top/mid/bass an shared mono sub channel's plus loads of other possibilities there for future development if only we can sort this I2S bus out first
as the Onkyo TX-SR875's with the HDMI problem are really cheap and a grate could be a really good DIY Gold Mine if its possible to activate the I2S and DSD bus coming from that hdmi board

ps, i have a raspi could i try to get the i2s bus working with that by any chance pls or is there any cheap usb to 4X i2s/6 ch dsd or anything thats really cheap and easy to get hold of here in the uk to start trying things out please ?

im also waiting for a single trace Oscilloscope i got cheap off ebay locally along with other stuff im slowly getting together for my new hobby, DIY Audio so expect to see knocking about on this forum more and moe as time go's on

please any help at all

paulflan is offline  
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post #6062 of 6062 Old 03-19-2015, 02:30 AM
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Picture seems better bypassing 875

Hi, I'm a new member and need some advice. My left front speaker no longer works, have checked everything and there is definitely no output from the amp.

Anyway, I've plugged my blueray (Sony PS2) directly into my tv via HDMI so I can put the 875 in to be updated and fixed, and have noticed the picture is much better than when it was previously running through the TX-SR875. Is this normal? The PS2 has no real video output settings so don't know the reason why.

Thanks in advance for your help.
Johno1972 is offline  
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