OEM Systems MS-21 — In-Wall Streaming A/V Receiver User Manual

Full user manual for the OEM Systems MS-21 In-Wall Streaming A/V Receiver — a Bluetooth/WiFi/AM/FM/AUX/USB touchscreen mainstation built on an automotive platform for residential, commercial, and RV environments.

Overview

The MS-21 uses the Android GO operating system and requires a reliable 2.4GHz WiFi network connection with internet service — no Ethernet port is provided (a mobile hot spot can be used). Due to limited 2.4GHz bandwidth, install a reliable WiFi network with multiple access points if needed; a Triband Mesh Network may be the best option if cabling for multiple APs isn't available. WiFi "range extenders" are not recommended. Without an internet connection, the device still provides AM/FM radio, local playback of digital files (internal, Micro SD, or USB), and Bluetooth playback.

Note: If controlling other devices on your network (thermostats, lights, etc.), ensure they are all on the same 2.4GHz network.

Audio/Video Inputs

• Internal A/V Storage, Bluetooth Audio, Micro SD, USB x3 (2 rear + 1 front, up to 32GB each; a USB charge jack is also on the front panel)
• AM/FM Radio, Internet-Streaming, AUX A/V (Composite), Smart Phone

Safety Instructions

• This is a permanently connected Class 1 apparatus — installation should be carried out by qualified service personnel per all applicable rules.
• Do not use this apparatus near water (bathtub, sink, wet basement, pool, etc.).
• Do not block ventilation openings; do not install near heat sources such as radiators or amplifiers.
• For speaker connections, use 18 AWG Class 2 cable or larger — 16 AWG stranded is preferred.
• If using an outdoor antenna, ensure the antenna system is grounded per Section 810 of the National Electrical Code (ANSI/NFPA No. 70-1984) to protect against voltage surges. Use No. 10 AWG copper (or equivalent) ground wire, secured with stand-off insulators 4–6 feet apart, with the antenna discharge unit mounted as close as possible to where the lead-in enters the house.
• Service should only be performed by qualified personnel if the power cord/plug is damaged, objects/liquid have entered the enclosure, the unit was exposed to rain, or the enclosure is damaged.

Installation

Included with the MS-21

Wire Harness, GPS Antenna, AM/FM Antenna, Remote Control, Torx® Driver & 4 Screws, 8 Wago Connectors, 8 Plugs.

Using the Installation Kit (MS-21-IK)

The MS-21 can be connected and operated from any 12–15V DC power source. For in-wall installations using 110–250V AC where the power supply is installed in the wall, the MS-21-IK is required — it contains an installation frame and a power supply with a 4.2mm mini connector safety-rated for in-wall installation. No other power supply is designed for this application.

Speaker Connections

For residential and commercial installations, trim ends off all wires except speaker outputs — do not trim speaker output wires. For each speaker wire used, remove insulation and twist the wire, connect using the supplied Wago connectors: fold the end over leaving approximately 11mm (3/8") exposed, flip up the connector lever, insert the wire fully, and flip down. Use the 3rd position for connecting an additional speaker.

Connections

Almost all connections use multipin connectors that are unique in size so they can't be interchanged. A zip tie is provided to support wiring. The AM/FM and GPS antennas connect at the rear panel — the AM/FM antenna can be dangled or attached within the wall interior (an attic-mounted or external antenna improves performance; a Motorola-to-F-connector adapter may be needed). The GPS antenna has magnetic or adhesive attachment. Power connects last via the polarized Mini power connector from the MS-21-IK power supply.

Attaching to the Wall

The wall opening should be cut to stud width, no greater than 15.5" (394mm) and no less than 14" (355mm), with a required opening height of 6.5" (165mm). Predrill mounting holes with a 3/32" (2.5mm) bit, using the MS-21 as a template and ensuring it's level. Secure with the 4 supplied Torx® screws and driver, then press the supplied screw caps into the holes (extra caps included).

Front Panel Layout

• Main Power Button: Turns power on/off, shuts down screen, changes mode.
• Home Button: Returns to APP screen / Home screen.
• Input Selector: Steps between Radio, Audio, Video, Bluetooth, etc.
• Mute/Standby: Short press to mute/unmute; long press (1 sec) for standby.
• Back Button: Returns to the previous screen.
• USB Charge Port: Up to 700mA charge current.
• USB Jack: For USB dongles up to 32GB (music, video, pictures).
• Micro SD Slot: For Micro SD cards up to 32GB.
• Microphone: For voice-to-text, audio recording, calls.
• Reset Button: Reboots the system (recessed — use a paper clip).
• IR Receiver: For remote control.
• Master Volume: Controls volume for all 4 audio channels.

Navigating the Screens

Setting Network/WiFi

1. Swipe down from the top to reveal the drop-down menu.
2. Select Settings from the menu.
3. Select Network from the Settings menu.
4. Touch the desired network and enter the password.

Setting Homepage Style

There are two available homepage screens (GUI options). Swipe down, select Settings, then Common, then Homepage Style to choose.

Setting Default Features

Automotive features (Brake warning, Reversing volume, Touch tone, Reversing Mirror) are only used in automotive environments and can be toggled here. Note: Brake warning must be off for video playback to function. Default system and call volume can also be set.

Setting Date and Time

Set manually or automatically via GPS/Network under Settings > Time. Choose Automatic date & time to use network-provided time, and Automatic time zone to use your current location.

Setting Brightness

Touching the Sun icon at the top of the screen toggles between Day Mode, Night Mode, and Dark. Adjustment settings are found in the Settings menu.

Using the Radio

The tuner dial changes station frequency by touch. RDS (Radio Data System) functions include AF (Alternative Frequency, default ON — seeks the same program on a different frequency when signal is weak), TA (Traffic Announcement, default OFF), and PTY (Program Type, default OFF — scans for genres like Sports, News, Music). Station presets are grouped as FM-1,2,3 or AM-1,2; press and hold a preset button for 2 seconds to program it. Auto-program automatically programs the strongest stations.

Working with Apps

Apps can be downloaded via the Play Store (log into or create a Google account). Not all Apps are compatible — those designed for portrait-only use or without scrolling may not display the full screen. Touch and hold an icon ~1 second to move it, or ~2-3 seconds to delete it. Apps on the home screen/bottom row cannot be moved or deleted. Apps cannot be placed in folders or hidden.

Modes of Operation

• Radio: Pressing Home or Back exits the radio screen while the radio keeps playing in the background.
• Music: Plays digital audio from internal storage, SD card, or USB. Not for streaming internet content (use a downloaded App instead).
• Video: Supports MP4, MPG, MOV, AVI, FLV, RMVB, 3GP, MKV in 1080 HD. Swipe right side up/down for volume, left side up/down for brightness.
• Aux: RCA analog A/V input for CD/DVD/Blu-ray players and phone/tablet outputs; video input accepts up to 480 lines composite. Input sensitivity is 1V. An HDMI-to-composite converter can adapt HDMI-only sources.
• Navigation: Requires WiFi; more accurate with the included GPS antenna. Google Maps is the default App (changeable in the Navi settings page).
• Bluetooth: Default pairing name is "mainstation," default passcode "1234." Recommended: set AutoConnect and AutoAnswer to OFF. Press and hold a paired device name 1-2 seconds to delete it.

Inputs and Outputs

• USB/SD: 1 USB + 1 Micro SD on the front panel, 2 additional USB on the rear. Each accepts up to 32GB (FAT32 or exFAT).
• Speakers: 4 outputs from 4 independent amplifier channels, rated for 4-8 ohm operation.
• A/V (Line Level): Rear panel output, can drive an amplifier or feed a secondary MS-21 to share A/V sources.
• Subwoofer: Up to 1V monaural full-range signal, no low-pass filter, linked to Rear audio channels.
• Remote Control: Handheld IR remote, ~10 ft (3m) line-of-sight range, uses a CR2025 battery.

Specifications

Service

Contact Customer Service: customerservice@oemsystems.com or 775-355-0405 (8AM–4PM PST, Monday–Friday).