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--- projects:yamaha_amp [2026/09/07 20:07] – ↷ Links adapted because of a move operation admin
+++ projects:yamaha_amp [2026/09/07 20:17] (current) – [Yamaha MCR-840] admin
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+~~META:
+title=Yamaha MCR-840
+description=Yamaha R-840 repair and hacking
+keywords=SEO, dokuwiki, disassembly, yamaha, R840, music, hack, hacking, audio, iPod, system connector, repair
+~~
+====== Yamaha Audio Amp/Receiver ======
+===== Disclaimer =====
+I am not responsible for any damages or injuries. Think before you do. \\
+Warning: The device uses mains voltage of course. So be cautious, e.g. when repairing standby-circuit! \\
+===== Yamaha MCR-840 =====
+Yamaha R840 is part of Micro Component System MCR-840 and comes with either CD-Player (MCR640), DVD-Player (MCR840) or BluRay-Player (MCR940). The players are connected via RCA but need a proprietary "System Connector" cable. The remote control is different for MCR640. \\
+The system comes with Yamaha NS-BP300 speakers in black or white which sound good. \\
+It has a coax Subwoofer-out. You can add Bluetooth capability via iPod-30pin dock or RCA. \\
+Unlock RCA-input of player with "hacking" [[projects:yamaha_amp#the_round_one|System Connector]] or [[projects:yamaha_amp#ipod-30pin_dock|iPod 30pin dock]] and use remote controls over UART. \\
+Unfortunately, it lacks Yamaha loudness control, which you might add with [[projects:yamaha_amp#yamaha_loudness|loudness circuit]]. \\
+{{:projects:yamaha:yamaha_mcr-840_micro_component_system.jpg?nolink&200|}}
+==== Repair & Service ====
+**Schematics / service manual**: \\
+[[https://elektrotanya.com/yamaha_mcr-840_mcr-940_mcr-640_r-840_ns-bp300_sm.pdf/download.html]] \\
+[[https://elektrotanya.com/yamaha_ns-bp300_r-840_mcr-640_mcr-840_mcr-940-.pdf/download.html|short version for R840 only]] \\
+__Self-Diagnostic Mode__: unplug device, turn balance completely to the left. Then press Pure-Direct button while plugging in the socket. Check error code in the service/schematics manual. \\
+Try resetting the error first in self-diagnostic mode, the device may function again (at least for some time). {{:projects:yamaha:diagnostics.pdf|download diagnostics only part of manual}}\\
+Read the block diagram from service manual: {{ :projects:yamaha:block-diagram.pdf |}} \\
+I have re-uploaded the necessary pages from service manual seen in hifi-forum threads for capacitor and resistor repair: {{ :projects:yamaha:yamaha-r840-repair.zip |}} \\
+=== Capacitor ===
+The stereo receiver has a standby circuit, which is permanently powered and uses a film capacitor (C13 with 22nF, 630V). Due to aging and impulse spikes the capacitor dies, the yellow LED just blinks and the receiver does not turn on.
+[[http://www.hifi-forum.de/viewthread-220-3031.html#15]] \\
+Replace with Polyester dielectric capacitor (MKT type), or better use one with polypropylene (MKP type). The voltage rating may also be higher than 630V. \\
+=== Resistors ===
+'Protection Mode' problem: \\
+There are four 68k 1/8W SMD resistors setting the constant current of the circuit. Replace them with >=1/4W metal film resistors (you can use THT too). Unfortunately, they are on the underside of the main PCB, so you have to remove a lot of components to get to the four 68k resistors R552, R553, R622, R623. \\
+See \\
+[[http://www.hifi-forum.de/viewthread-220-8212.html]] \\
+and \\
+[[http://www.hifi-forum.de/viewthread-220-3031.html#32]]
+**Note**: [[http://www.hifi-forum.de/viewthread-220-9800.html#5|A-S1000 has similar issues]]. \\
+[[http://www.hifi-forum.de/viewthread-220-9660.html#34|R-N602 also has the Protection Mode problems]]. \\
+Probably more Yamaha systems can be repaired in that scheme. \\
+==== Remote control ====
+There is nothing much to say. It is a simple iR remote control. The main IC is marked "2428662 03160". \\
+iR codes for R840 can be found on page 80/150 of service manual (next to remote control schematic). \\
+Here is an unspectacular insight: \\
+{{:projects:yamaha:rc1.jpg?125|}}
+{{:projects:yamaha:rc2.jpg?200|}} \\
+I have taken the pictures so you can see at which positions the holding clips are - don't forget about the single screw in the battery compartment.
+The buttons and their layout of remote control for DVD and BD versions differ slightly. \\
+==== Disc Player manual eject ====
+The players only turn on with system connector plugged into R840 amp (see [[projects:yamaha_amp#the_round_one|below how to simulate system connector]]). \\
+To eject disc from player without power, the manual says to slide a flat head screwdriver in the slot at the bottom. \\
+{{:projects:yamaha:disc-eject.png?direct&175|}}
+==== System Connector ====
+=== the round one ===
+The system connector is used for a connected disc player. It enables the RCA-input for the player and also transfers signals like power-toggle and remote control signals. \\
+It uses proprietary 8‑pin DIN connector (find the cable under name "MINI DIN 8-PIN MD8"). You can find the socket under name [[https://www.datasheets360.com/pdf/-8209950980056158734|"CMS 5008-0101"]] - Yamaha part number is //AAX09170// (for Yst-MS30). The MD8 cable itself is called “ZP512100”. \\
+Pinout from service manual: {{:projects:yamaha:systemconnector.pdf|}} \\
+**Pin5 is +10V** from amp to player. \\
+Test system connector: {{:projects:yamaha:syscon-test.pdf|}} \\
+{{:projects:yamaha:system_connector-pinout.png?direct&400|}} \\
+system connector pin descriptions: \\
+{{:projects:yamaha:syscon-pins.png?direct&200|}}
+{{:projects:yamaha:syscon-schematic.png?direct&200|}}
+{{:projects:yamaha:system-connector-connection.png?direct&200|}}
+MD8 "ZP512100" cable is not only used by MCR-840 but also various other systems like MCS1330 (R1330 + CD1330). As I do not own anything else but R840, I cannot say if other devices use the same protocol or even pinout! Always check yourself before. \\
+== communication signal ==
+Even though lines are called MISO and MOSI in service manual, the communication is UART tx/rx. BAUD is 9600, 8bits, 1start+1stop bit, no parity, LSB first; \\
+First two bytes are always 0xFF 0x55. \\
+Last byte is checksum = (~(sum(bytes_except_checksum) & 0xFF)) & 0xFF \\
+For the bytes in between, see source code. \\
+#TODO unlocking CD-Player RCA input + remote controls + USB\\
+#TODO upload pulseview logic analyzer snippets \\
+=== the flat one: writing port ===
+This is just an FYI, IMO we cannot do anything useful with the port. \\
+Yamaha devices use a so called "writing port", a flat cable, e.g. to flash ucom via RS232-adapter. It is known for updating firmware over PC software (which we don't have). \\
+R840 uses Renesas M16C/64 R5F3640DNFA MCU. Service manual states to use FlashSta.exe (which we don't have, neither R840_xxx.mot + R840_xxx.id firmware), FYI see [[https://www.renesas.com/en/document/mat/m16c-flash-starter-m3a-0806-users-manual?srsltid=AfmBOoouDn1Ckenn0l-1YUgHz2BwZHPVGnbNhIjZUAa85k5-iwqpdRbM|Renesas M16C flashing guide]]. If you still want to look into flashing M16C MCU go to
+[[http://www.m16c-flasher.de/]] or [[https://m16c.mikrokopter.de/]]. There is also an OSS flasher on github [[https://github.com/truhy/m16c-flasher]] fixing some of the problems. \\
+Writing port of R840:
+{{:projects:yamaha:writing-port-r840-pins.png?direct&200|}}
+of DVD player:
+{{:projects:yamaha:writing-port-dvd-ucom.png?direct&200|}} \\
+Note that manual says two different adapters are needed - the voltage level is not the same. \\
+Other Yamaha receivers also instead use D-Sub connector for RS232. \\
+Jump to [[projects:yamaha_amp#other_interconnections|RS232 sample projects]] \\
+===== iPod-30pin Dock =====
+There are pre-amplified Apple iPod-30-pin to Bluetooth adapters cheaply available, even with APT-X codec - smartify your stereo-system :) \\
+Make sure the input on the iPod dock (like Bluetooth adapter) is pre-amplified - (the cheap adapters are commonly not)! \\
+iPod dock is basically another line-in input (here not pre-amplified) with UART RX/TX lines for iAP commands. \\
+So, if you want an even better DIY-upgrade and not the ready2buy Bluetooth adapter solution, read on.
+Page 64 of manual: {{ :projects:yamaha:ipod.pdf |}} \\
+Also see Page 65 of service manual. \\
+To repurpose iPod dock to another audio source, see [[projects:ipod-simu#ipod_30pin_device_simulation|iPod 30pin device simulation]] page \\
+#TODO insert remote controlling \\
+#TODO add custom PCB for iPod dock replacement \\
+===== Other +Yamaha =====
+**RTFM:** [[awesome-pages:start#links|See the links to search for service manuals, schematics and docs]] \\
+[[http://www.hifi-forum.de/viewthread-220-9029.html|hifi-forum.de Yamaha R-S300 repair]] \\
+==== USB iPod iAP ====
+Receivers with USB can use its iPod input if available. RC and CoverArt possible. \\
+Note: [[https://github.com/pamaury/rockbox/blob/master/apps/iap.c|RockBox-Player supports iAP]] \\
+- [[https://github.com/sparkfun/SparkFun_Apple_Accessory_Arduino_Library|SparkFun precompiled ESP32 Arduino iAP2 library]] (closed software) \\
+- [[https://github.com/oandrew/ipod-gadget|iPod USB HID on Linux]] \\
+- [[https://github.com/wiomoc/iap2/|iap2]] and read [[https://wiomoc.de/misc/posts/mfi_iap.html|its blog writeup]] \\
+- [[https://blog.adambell.ca/posts/20250116-McLarens-And-CarPlay/|Writeup of iPod-USB play in McLaren]] \\
+- [[https://github.com/geniass/pipod|PiPod]] using ipod-gadget lib \\
+- [[https://github.com/oandrew/ipod|iAP ipod in Go]] \\
+FYI: Texas Instruments’ CC256x Bluetooth modules have optional software add-ons for iAP support in the module / stack, so there is no need to implement the full protocol. \\
+==== Yamaha Loudness ====
+Loudness compensation is used to maintain a balanced sound at different volume levels. At low listening volume levels, the bass drivers need to produce more sound pressure to be perceived at the same level as the mid and high frequencies. Unfortunately, R840 has no loudness build-in. \\
+See a collection of schematics for loudness circuits here: [[http://www.hifi-forum.de/viewthread-71-12517.html]] \\
+{{:projects:yamaha:loudness-schaltung-yamaha.png?direct&200|}} \\
+#TODO software implementation of loudness \\
+#auto-volume level + auto-level loudness curve \\
+#add dynamic range compression \\
+==== other interconnections ====
+[[https://github.com/p/seriamp/]] Receiver & Amplifier Serial & Network Control Toolkit \\
+=== RS232 example projects ===
+RS232 connection has be done to various receivers, e.g. see the following: \\
+- [[https://github.com/joba-1/Joba_RxV1600|RxV1600 RS232 on ESP32]] \\
+- [[https://github.com/memphi2/homie-yamaha-rs232]] Homie MQTT for openHAB with ESP8266 serial \\
+- [[https://github.com/firefrei/yrxv1500-mqtt]] rs232 to mqtt \\
+- [[https://github.com/akentner/yamaha-avr2mqtt]] rs232 with nodes.js \\
+=== system connector: the audio jack one ===
+Yamaha Soundbars use an audio jack as "system conector". It is a control voltage which can also be used to to switch a relais ~9-12V, consider using DC-DC isolated converter
+[[https://www.youtube.com/watch?v=KfUnEoQaNIs]] \\
+=== http / net ===
+[[https://github.com/BrenekH/yamaha-rcp-docs]] Remote Control Protocol (RCP) \\
+[[https://github.com/honnel/yamaha-commands]] http API \\
+[[https://github.com/Raynes/rxvc]] \\
+[[https://github.com/wuub/rxv]] \\
+[[https://github.com/soef/y5]] JS simple API \\
+[[https://github.com/mvdwetering/ynca|YNCA protocol communication]] \\
+[[https://github.com/memphi2/homie-yamaha-rs232]] Homie MQTT for openHAB with ESP8266 serial \\
+[[https://github.com/mvdwetering/yamaha_ynca|Yamaha YNCA for HomeAssistant]] \\
+[[https://www.npmjs.com/package/iobroker.musiccast|musiccast for iobroker]] \\
+- Of course there are plugins for various Yamaha network receivers for smart home like HA ioBroker etc \\
+[[https://github.com/coffeegreg/YTuner|YTuner ]] and [[https://github.com/milaq/YCast|YCast]] replace vTuner internet radio service for AVRs \\
+=== MusicCast ===
+[[https://flows.nodered.org/node/node-red-contrib-musiccast|node red musiccast]] \\
+[[https://flows.nodered.org/node/node-red-contrib-yamaha-yxc|node red YXC]] \\
+[[https://github.com/mase1981/uc-intg-musiccast|Musiccast on Unfolded Circle Remote 2/3 remote controls]] \\
+[[https://github.com/neutmute/swimbait]] Emulates a Yamaha MusicCast as ASP.NET application \\
+[[https://github.com/ddecockbe/yamaha|openHAB Yamaha basic MucicCast control]] \\
+#TODO: DLNA \\
+#TODO: investigate if bt-audio-sync force is possible (aka MarantzNR) \\
+=== iR codes ===
+[[https://github.com/theCstokes/YamahaRemote/blob/master/IR_RX-V667-3067_rev0.0_Full.xls|yamaha V667 etc iR codes]] \\
+===== Yamaha RX-797 =====
+Unfortunately, also my RX-797 suffers from standby power circuit issue. See the following information: \\
+Service manual for RX-797: [[https://audiocircuit.dk/downloads/yamaha/Yamaha-RX797-rec-sm.pdf]] or [[https://manualzz.com/doc/54715564/yamaha-rx-797-service-manual]] \\
+Repair amp not turning on: [[https://www.hifi-forum.de/viewthread-220-4045-2.html]] \\
+and [[https://www.hifi-forum.de/viewthread-220-9427.html]] \\
+and [[https://www.diyaudio.com/community/threads/yamaha-rx-797-no-power-to-device.272688/]] \\
+tldr;
+   * Disconnect speakers and all inputs.
+   * Try DIAG / Self Diagnosis Function: hold FM/AM + 8, press MASTER, and continue holding the two buttons for at least 3 seconds. **WARNING: DIAG startup disables most protection circuits and can cause further damages if genuine amplifier fault!**
+   * If absolutely nothing lights/clicks, DIAG itself probably cannot run because the standby supply/CPU isn't being powered correctly.
+   * Unplug the receiver and inspect/test film capacitor C254.
+   * On a 230 V European unit, C254 is 0.022 µF = 22 nF, polypropylene, 630 V (it is bad below ~15 nF). (For North American versions it is 47 nF / 400 V)
+   * Check nearby R251 (2.2 kΩ / 1 W) and the rest of the standby supply if C254 measures correctly.
+   * If C254 did not fix it, see other components of standby-supply, including Q254, D259 and C258.
+===== Related =====
+#TODO: Onkyo,Marantz,Denon system connector \\
+Denon remote control connector [[https://kfigiela.github.io/2014/06/15/denon-remote-connector/]] \\
+Onkyo control library [[https://github.com/zarpli/onkyo]] \\
+=== OSS apps ===
+Enhanced Music Controller: [[https://github.com/mkulesh/onpc]] Helios OSS replacement for Onkyo, Marantz, Denon etc., [[https://f-droid.org/packages/com.mkulesh.onpc/|direct F-Droid link]] \\
+=== legacy ===
+Consider using [[disassembled_devices:chinese_bt_fm-transmitter|Bluetooth to AUX and FM transmitter]] adapters to add wireless audio to your non-wireless system. There are cassettes with line-in and even bluetooth too.\\
+There are pre-amplified Apple iPod-30-pin to Bluetooth adapters cheaply available, even with APT-X codec - smartify your stereo-system :)\\