Repair/upgrade of Onkyo HT-RC430 AV Receiver - Hardware Details

Name in the source codeESP32 or MCP23017 pinother end comment
HSPI_MISO12 n.a. not used, display is write-only
HSPI_MOSI13P701 22M66005 display controller MOSI
HSPI_SCLK14P701 23M66005 display controller SCLK
HSPI_CS 15P701 21M66005 display controller chip select
SPRLSPBGPA7P8002 1'B' and surround speaker relay
SEC1H GPA6P8002 2more power control
AMUTE GPA52 transistor mute driver circuitmute all audio
SEC1OFFGPA4P8002 4more power control
SPRLF GPA3P8002 6front speaker relay
MPOWER GPA2transistor driving JL901 1main power
BTPOWERGPA1base of 2N2907 to power BT modulebluetooth power
LEDSTBYGPA0LEDfront panel LED
REPEAT GPB0transistor base to drive "repeat" buttonbluetooth board repeat button
PREVVDN GPB1transistor base to drive "previous" buttonbluetooth board previous track button
NEXTVUP GPB2transistor base to drive "next" buttonbluetooth board next track button
PLAYPAUSE GPB3transistor base to drive "play/pause" buttonbluetooth board play/pause button
BTMODE GPB4transistor base to drive "mode" buttonbluetooth board mode button
KEYPIN0 39 P701 2 analog input for key scan group 1
KEYPIN1 36 P701 3 analog input for key scan group 2
KEYPIN2 34 P701 13 analog input for key scan group 3
KEYPIN3 35 P701 15 analog input for key scan group 4
POTA 4 P701 12 digipot A
POTB 5 P701 14 digipot B
DISP_RES 16 P701 19 display reset
VOLDATA 19 P8002 5 data line to audiofp device (R2A15218FP)
VOLCLK 23 P8002 7 clock line to audiofp device
SPRLCS 2 P8002 8 center/surround speaker relay
TUNER_RES18 P8001 2Tuner Reset
ESP32_I2C_SDA21 P8001 4 & MCP23017 SDAI2C TUNER & MCP23017
ESP32_I2C_SCL22 P8001 6 & MCP23017 SCLI2C TUNER & MCP23017
HS_TEMP 33 JL501 3 heat sink temperature from LM61 - V = 0.6 + tC/100
HP_DETECT17 P8001 18 head phone detect - low when not plugged in
I2S_BCLK 25I2S module BCLKI2S DAC for Internet Radio
I2S_DOUT 26I2S module DOUTI2S DAC for Internet Radio
I2S_LRC 27I2S module LRCI2S DAC for Internet Radio
unused32n.a.analog/digital
unusedGPB5n.a.digital
unusedGPB6n.a.digital
unusedGPB7n.a.digital

Other Hardware

I added a small switching supply from the power cord input (i.e. unswitched) that supplies 9V to the ESP32 board via a 7805 regulator. (The ESP32 has a regulator of it's own to make 3.3V). The ESP32 is always running as long as the line cord is plugged into mains electricity.

The "power" LED is one glued into a hole I drilled in the "O" in "Onkyo", because I coudn't find a power LED on the front panel PCB. It is driven by the output called "LEDSTBY". It flashes during boot up; 1 time, 2 times, 3 times, 4 times, and 5 times once it is fully up and has a WiFi connection. The ESP32 only boots up when power is applied; the "ON/Standby" just tells the ESP32 to turn off most of the power in the unit, save the ESP32 itself.

The speaker connectors have had Banana jacks wired up in parallel with the A and B speaker outputs, because the stock speaker connectors suck.

William Dudley
April 19, 2025

More photos


The amplifier driver board, which claims to be class A. It sure throws off some heat when listening at moderate levels. At top of photo you can see the temperature sensor (an LM61) attached to the heat sink.


Detail of part of the stock CPU board, showing the places where a wiring harness was soldered in, that I connectorized.


The stock CPU board after I connectorized the soldered connections, so I could remove/replace it at will.


The power supply section (and part of the amplifer at bottom). A good part of the power supply circuitry is on the video I/O board, which you cannot see.


Rear view of the unit with the tuner removed, hence the two holes labeled "AM" and "FM 75Ω".


Close up of the VFD driver chip after I replaced it, showing bodge wire because I destroyed a track in the process.
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