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Post by madmal on Feb 22, 2024 13:01:50 GMT -5
Hello forum members.
I have one of these to repair that has an issue at cold power up. There is is no audio for a minute or two afterwhich sound comes up ok. Even after subsequent restarts. Only on the first power up after being off for a while recreates the fault.
Seems like an issue only when cold.
With it being a Pioneer I suspected DSP issues so have tried using freezer on the Dolby chip and the two ADSP chips. I can't recreate the fault this way.
There are no issues with firmware diagnostics and no errors like e22.
Next plan of action is to check all supplies around the main dsp/hdmi board using a multimeter and scope.
Has anyone experienced this or similar? I know the earlier versions of the DSP chips were prone to issues but this is a 2018 receiver with a D808K013DPTP5 DSP.
Thanks
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Post by madmal on Mar 1, 2024 7:06:19 GMT -5
Update, have spent a bit of time looking at this. All main power supplies are fine with no noise, also checked all power on the main board 3.3 and 1.2 supplies, all clean. I think I've narrowed this fault down to the audio board which have the input switchers and volume control chips. I suspected the +7 -7 supplies but they also check out ok. Zone 2 and Zone 3 audio work fine during the fault period when there is no audio on main zone, audio for these is processed on this same board using the same supply lines. On the audio board there are two BD34704KS2 audio processors, these do bulk of input switching and and volume control. There are also 2 smaller chips which do volume for Zone 2 and Zone 2 which must be ok. I could do with some help in determining the audio paths as it's very confusing trying to work this out just from the schematics. I'm used to Denon and Marantz manuals with good block diagrams showing all the flows. The Pioneer service manual is very poor in this regards. I know the BD34704KS2 pins 60 to 69 has DSP inputs but not sure which way signals are route, i.e. from source ADC into the DSP then DAC etc.. I could just replace the BD34704KS2 but would like to understand what's going on. Not easy as that board is 2 beneath main HDMI board. Thanks  |
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Post by mastertech on Mar 3, 2024 11:30:21 GMT -5
I have only had a small amount of time to look over the schematics but so far I am not thinking it is either one of the BD34704KS2's. As I get time I will look some more.
Do you know if the main preamp outs work when the speaker outs do not?
Which model unit is this?
When it is not working have you tried analog or digital input or both?
When not working have you tried HDMI using pass through audio to see if there is sound on TV?
Does this unit have a Direct or Pure Direct setting to bypass DSP?
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Post by madmal on Mar 5, 2024 4:52:09 GMT -5
Hi
1) Pre-amp outs also do not work when the fault is there. Also no Sub out, this confuses me somewhat as Sub out 1 and 2 are split between the two BD34704KS2 chips, I would have expected one of the two Sub outs to be ok if my theory is correct but this is not the case.
2) SC-LX801 but according to the manual, Pioneer MODEL No.SC-LX701/801/901, Onkyo TX-RZ1100/3100, DRX-7/R1,PR-RZ5100,DRC-R1 are all the same in this area.
3) HDMI pass through works fine, ARC also fine (when problem not there).
4) Analogue inputs also have the same issue.
5) Direct/Pure does not make any difference to the issue when it occurs.
6) One additional bit of info, all the speaker symbols in the display are always correct even when there is no sound. Is this another sign DSP is ok?
A little bit of further diagnosis, freezer on IC301 (BD34704KS2) does seem to recreate the problem and it lasts longer, but it's a bit hit and miss as it's not easy to get to it when the unit is fully assembled. Looking at the manual after these chips it's pure analogue all the way to the amps, there are some buffer stages in the path but the fact that Zone2 and Zone 3 work fine I can't see this being an issue on the amp board. Also when the fault is ongoing turning up the volume really high you can hear the source very faintly which also proves to me that all AD DA DSP most likely is ok.
Looking at sources for BD34704KS2, seems Farnell and Mouser have them but excessive handling charges.
I'm interested to hear your thoughts on why you think the fault cannot be the main BD34704KS2?
Thanks for your help Mastertech, hopefully we can both learn from this one.
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Post by madmal on Mar 14, 2024 12:10:52 GMT -5
Update.... Mastertech you were right. Chip replaced no joy. Will have to spend some more time on this one.
And also, pure direct from an analogue source does work when fault is present. My mistake, I didn't know we had to also set front speakers to large for pure direct to bypass digital processing. Wish I had been more thorough in this as it was a pain to replace that chip.
So now.... I suspect dac or dsp issues.
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Post by madmal on Mar 19, 2024 6:07:45 GMT -5
Update.... I2C signals leaving main digital board towards DAC during fault condition confirmed good.
Issue must be on the DAC board.
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Post by mastertech on Mar 19, 2024 17:16:44 GMT -5
Keep going. I'm sure you will find it.
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Post by madmal on Mar 20, 2024 6:54:25 GMT -5
Yep studying the manual anytime I have a moment.
I think I'll have to add a few test wires at points of interest on the DAC board then assemble it again to take measurements and readings.
If you have some tips that would be good.
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