Onkyo TX-SR607 no sound, but DSP firmware seems OK

Yes, I've done both of those things (reset it several times!). idling xcurrents are alls et where they should be as per the service manual. But no difference unfortunately, still no sound on digital inputs..

HDMI video is working fine (OSD and source signal), audio only comes through when using analog RCA inputs (i.e. assigned to ------, not HDMIn, COAXn or OPTn), and only in PureAudio or Direct mode.

Further testing: when using DVD / HDMI1 input, playing a DTS source at 48KHz, DSP Debug mode displays 7 D 32K 1 N / 2 FF ? X 4. Each value has a meaning, according to the service manual, as follows:

Value 01. Blank: DIR Input Lock = Lock. I think this is normal, as the only other value is "E" = Unlocked, which means no input signal to DIR.

Value 02. 7: DIR Input RX. I think this means HDMI1 as it changes to 8 when I use HDMI2.

Value 03. D: DIR/ ADC Fix Mode = Digital (SPDIF). 1 don't know whether this is correct, as I'm using HDMI1 (not Coax or Opt) - is HDMI audio the same as SPDIF?

Value 04. 32K: Sampling Frequency, Emphasis = 32 KHz without emphasis. The displayed sampling frequency, which is different from the input signal (48KHz)

Value 05. 1: DIR Detect Type =PCM.  The displayed format, which is different to the input signal (DTS)

The manual gives the cause of the trouble for values 03 and 04 as "No input signal to DIR" , and that the remedy is to "Confirm where the digital waveform stops
between the digital input and DIR; resolder pins of the bad part or replace it with a new one".
 


I do have a cheap digital oscilloscope. But even following the circuit diagram, I can't see where I need to measure the digital waveform and what it should look like, and I can't easily get to any measurement points when the receiver is assembled in the chassis with its various boards plugged together. Any help with this would be most appreciated.


Moving on.....

Value 06.  N: CODEC Clock Mode = Normal

Value 07. 2: DSP Port Status, Bit 2 = busy. The manual says this is an abnormal state and the cause is "connection from DIR to DSP is no good". The remedy is to "confirm where the digital waveform stops
 between DIR and DSP by oscilloscope; P8001, P8002 (connection pins) may relate.; Resolder pins of the bad part or replace it with
 new one". Again, I don't know where / how to measure this  and any help would be appreciated.

Value 08. FF: DSP Sequence = Free. I think this is OK.


Value  09. ?: DSP Detect Format = Unknown Format. The manual gives the cause as "Input signal to DSP is no good". Same remedy as value 07 above.

Value  10. X: DSP Decode = Decode NG. The manual gives the cause as "No input signal to DSP" or "Interface between DSP and MPU is
 no good". The remedy is to "confirm where the digital waveform stops
between MPU and DSP by oscilloscope; P8001, P8002 and P8003 (connection pins) may relate.; Resolder pins of the bad part or replace it with
new one". Again, I don't know where / how to measure this and any help would be appreciated.

Value 11. 4: Mute output device. According to the manual, this is a hex number which, when transformed to binary, each bit indicates
 the IC which outputs an error to the microprocessor, which then output
 Audio Mute. A hex value of 4 is 0100 in binary, and the manual says that the second bit means it's the DSP chip (Q201) that's at fault. I don't knwo whether this indicates an actual  DSP fault,  or is a symptom of other errors (e.g. no digital signal reaching the DSP).

Anyway, from all this, it looks like I might have a range of potential problems anywhere between input digital signal to DIR, DIR to MPU, MPU to DSP and/or a fault with the DSP chip itself.

So I'm now wondering if it's worth going on or whether I should just bin it at this point. Any advice or suggestions most welcome.

Thanks.

Thanks Todd, that's very helpful. I did wonder whether the analog signals were being digitized / undigitized but was of the understanding (from the user manual) that Pure Audio and Direct mode on the analog inputs would bypass the digital stream completely. But I don't know if this is correct, and the service manual isn't much help on this. Anyway, I'll check all the items you mentioned (or their equivalents from the SR607 schematics) and see how it goes. Good tip about not using a solder sucker, I've had similar issues with tracks lifting on SR606 HDMI boards when removing / replacing failed caps (successfully I'm glad to say). I've found it best to use wick and a very fine-tipped temperature controlled iron, and not spend too long on each joint.

Fingers crossed!
Jon.

Wow that's great information. Thank you so much. This is where I've got to....

I started checking for a digital signal at some of the test points, using COAX1 as input. I couldn't find anything after DIR, and SAI_SDOUT or RMCK didn't register anything either.

So I thought I'd check the supply rails to DIR. The +5v rail is fine, but the +3.3V rail reads only 384mV anywhere from the 3.3V regulator (Q746) output to DIR. Everything looks OK visually, and the rail is continuous across the various coils. The rail to GND resistance measures only around 5 ohms though.

I then removed L306, just before the +3.3V rail goes into VLS (pin 53) and VLC (pin 6) of DIR (Q301), to try to isolate the fault. The rail from the regulator to the left side of the L306 gap now reads correctly at +3.3V. Putting a meter across the L306 gap reads around 85mA. The left side of the gap (regulator side) reads around 62K Ohm to GND; the right side of the gap (DIR side) still reads around 5 ohms to GND. 

The only other components to the right of L306 appear to be C319, C314 and C315, between the rail and GND. So now I'm thinking either one of those caps is faulty (unlikely) or DIR is faulty (more likely), or the regulator is faulty and unable to deliver sufficient current (possible?).

I don't know where to go from here. Any more ideas?

Thanks,

Jon.