Help Sony AU BUS for SDP-D905 - Page 1
Forum section: electronics / repair

author: relax79
author_rank: Contributor
timestamp: February 28, 2018, 10:48:12 pm
content: Hello friends, sorry for m poor English, I have a sony sdp-d905 signal processor, this is part for lbt-d905 stereo systems. It works only digital input, I am must turn to input analog but only works with using ta-d905 amplifier and connecting au bus cable. Amplifier decides processors input, I have not an amplifier and I must activate the analog input. In service manual au bus looks like one wire protocol and I have bus pirate for connecting to au bus but I do not know what commands needs for this. Anyone familiar or observe this protocol with logic analyzer or do it for me if have this system in the hand. Thanks

author: Electric Canary
author_rank: Newbie
timestamp: September 20, 2020, 05:22:07 pm
content: Hey!I know this is a very old post but I had the exact same problem and here's how I managed to get the analog input/output back. This is a crude method and it deactivates the digital inputs and the AU bus. However I'm not too sad about that since RCA seems to be way more popular and I don't have the whole LBT-D905 system.IC501 is responsable for the input selection and the mute switching.Basically you need to ground pin 25 and 32 to unmute the analog path. Then you have to put 5v to pin 29 (it selects between analog and digital input). To do that I unsoldered pins 32 to 25 of IC501. You can probably get away with unsoldering just pin 29 and grounding the rest of them. You will find 5v at pin 33 to connect to pin 29.Once your signal path is set, I measured a -2dB difference at the output. You can compensate that by grounding pin 58, it activates a 2dB boost at the output.I found this method by checking the repair manual again and again. Not sure if there's any flaws other than deactivating digital inputs and au bus.

author: Gavinda
author_rank: Newbie
timestamp: January 14, 2022, 12:39:02 pm
content: First i need to thanks for your method sharing.I also has same problem & while i searching for solution i found your method.Could you please help me how to select 2 other digital inputs ??

author: tooki
author_rank: Super Contributor
timestamp: December 10, 2022, 07:30:02 pm
content: FYI, electrically, the AU BUS is the same as the later Control A system for audio gear, which is electrically the same as the Control A1 system, which was later extended to Control A1 (II), as well as Control S (for AV gear) and Control L (also known as LANC with various connectors, for camcorders). They’re also all often combined under the “S-Link” umbrella, so you’ll often see the terms used kinda interchangeably. Regardless, it’s all a 5V open-collector bus. You can find the pinouts in service manuals, but you can also just turn it on and measure the voltage: when you’re showing +5V, your positive probe is on the data line and negative is on ground.The differences are in the signal format, but all are apparently variants of SIRC, Sony’s IR remote control format, and some service manuals even refer to the Control A bus as SIRC. There are various Arduino projects out there to control this, mostly for A1(II) and LANC.As I understand it:Control-S is simply standard Sony IR commands, without the 40kHz IR carrier frequency. Seehttp://www.armory.com/~spcecdt/remote/control-S.htmlhttp://boehmel.de/sircs.htmI have a strong suspicion that AU BUS and Control A are exactly the same thing as Control-S, and that all of them except Control-L are fundamentally little more than different versions of SIRC (which exists in 12, 15, and 20 bit versions).Control-L/LANC omits the device address, since it’s only ever used for 1:1 connections, and apparently is shifted by one bit:http://boehmel.de/lanc.htmAU BUS seems to have been used for a long time, always between devices in integrated systems.Control A seems to be quite rare, found only on a few devices before Control A1 came along around 1995 or 96.Control A1 appears to be a major departure from Control A, with only limited interoperability:https://www.minidisc.wiki/_media/resources/sony_s-link_control_a1_control_system.pdfControl A1 (II) extends A1 to allow bidirectional communication, but remains essentially compatible with A1:http://boehmel.de/slink.htmThis project page has a bunch of links to info on the protocol:https://github.com/Ircama/Sony_SLinkThere are various online repositories of IR codes, and that may include Sony codes suitable for the device in question.

author: tatanka
author_rank: Newbie
timestamp: December 27, 2024, 08:25:48 pm
content: Hi to everybody. Me and my son have found the fix to this issue. We have two of these Sony processors. In fact we have four proccesors, but two of them does not work fine due to the problem you describe in your post. One of them is stuck on the digital signal and due to this we can hear the compact disc module but no more, without having access to the rest of modules. With the other module, just the opposite occurs. Only works with analog signal so we only can hear analog devices, no CD readers.We tried your solution without succeed. After that we tested the continuity of the tracks from the aubus connector to the ic 501 integrated. For some reason It´s easy to take for granted the problem was on the ic 501 or at least that was our mistake. However we realized there was one or more discointinuities in some place of the three tracks that goes from the aubus connector to the ic 501 integrated. The discontinuity track points of the board can be seen on the photos (before and after the fix). There were just next to the connector. Atl least in one of the units. On the other there was only a point of discontinuity, just the track in the middle of the three tracks. I tend to think tracks break due to the use and movements of the connector when the aubus wire is plugged and unplugged over the time. Surprisingly, the issue is not visible at first sight. Apparently the tracks are in good condition but actually there is no continuity on no one of them.Once we have bridged the tracks in bad conditions the aubus wire and the tracks started to work without issues in both devices.We don´t know whether this will be the solution for all those who has the module stuck in one of the two options, either analog or digital. Surprisingly we detect the same fail and fix in two of our four proccesors. The conclusion for us is clear. When one of the tracks that start from the aubus connector is broken communication among the different modules does not work fine, and you have got your device stuck in one of the signals, either analog or digital depending on witch of them is broken or cut off.

author: Alex1996123
author_rank: Newbie
timestamp: May 10, 2025, 09:31:26 am
content: Hello, I am facing the exact same issue. I would aprreciate it if you could explain it further and clearer, as I am havin trouble following the insrtuctions. Many thanks!!!