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| boAt Stone 1000 circuit details showing the Bluetooth module, ft2920P amplifier IC, AUX input, charging IC and important repair sections. |
boAt Stone 1000 Circuit Overview.
The boAt Stone 1000 is a portable Bluetooth speaker built around a compact audio circuit that combines wireless audio reception, wired AUX input, audio amplification, battery charging, control switches, and speaker output on a single PCB. The reported motherboard reference for this unit is BK_M33_BT_v2.
According to the supplied board information, the speaker uses a ZT-4390E5 Bluetooth module, ft2920P audio amplifier IC, PT2308-S headphone driver IC, 4056A charging IC, and additional transistor-based switching and signal-control stages.
The circuit is easier to understand when it is divided into four sections: the Bluetooth and audio input section, audio amplification section, power and charging section, and user-control section.
Because component markings and battery ratings can vary between revisions, the values printed on the actual PCB and battery should always be treated as the final reference during repair.
boAt Stone 1000 Basic Specifications.
The supplied information identifies the speaker as boAt Stone 1000, with an estimated power range of approximately 14–20 watts and Bluetooth Version 2 listed in the source material.
The board information is as follows:
Model: boAt Stone 1000
PCB Number: BK_M33_BT_v2
Charging Connector: Micro USB
Reported Bluetooth Module: ZT-4390E5
Audio Amplifier IC: ft2920P
Headphone Driver IC: PT2308-S
Charging IC: 4056A
Transistors: J3Y and A119V
Push Switches: 4
AUX Input: 3.5 mm audio jack
Battery: Internal rechargeable battery
The supplied component list contains four major IC-based sections along with the Bluetooth module, AUX jack, switches, transistors, battery, and speaker-related circuitry.
boAt Stone 1000 Circuit Block Diagram.
A simplified signal flow can be understood like this:
Bluetooth Device → ZT-4390E5 Bluetooth Module → Audio Signal Processing → ft2920P Amplifier → Speaker Output
For a wired connection:
AUX Input → Audio Signal Path → ft2920P Amplifier → Speaker Output
The charging path is separate:
5V Micro USB Input → 4056A Charging Circuit → Battery → Power Rails for the Speaker Circuit
The push buttons connect to the control section and are used for functions such as power, volume, mode selection, and track control.
Bluetooth Module: ZT-4390E5.
The reported Bluetooth module number is ZT-4390E5, with C5BF mentioned as another marking.
Its primary job is to receive wireless audio from a paired mobile phone, tablet, computer, or another Bluetooth-enabled source. The module converts the received wireless data into an audio signal that can be passed to the speaker's audio processing and amplifier section.
The supplied information mentions 26 MHz in connection with this module. However, the exact role of a crystal or oscillator marking should be confirmed from the physical PCB before using it as a definitive RF specification.
How the Bluetooth Audio Path Works.
When a phone is connected over Bluetooth, the module handles the wireless communication and produces the corresponding audio signal.
That audio signal is then routed toward the amplifier stage. The ft2920P increases the signal to a level suitable for driving the speaker.
This arrangement separates wireless reception from high-power audio amplification, making troubleshooting easier because a fault can often be isolated to the Bluetooth section or the amplifier section.
Bluetooth Repair Checks.
When Bluetooth is not working, the first checks should include:
Supply voltage at the Bluetooth module
Power switch and control circuit
Visible PCB damage
Loose or broken solder joints
Crystal or oscillator-related components
Audio output from the Bluetooth section
Shorted capacitors around the power rail
If Bluetooth pairing works but there is no sound, the Bluetooth module itself may not be the problem. The fault can instead be located in the audio signal path, amplifier input, amplifier power supply, or speaker output stage.
AUX Input and Audio Female Jack.
The boAt Stone 1000 also includes a 3.5 mm AUX input, allowing audio to be supplied through a wired connection.
The AUX input is useful when a source device does not support Bluetooth or when a wired signal is preferred.
How the AUX Signal Reaches the Amplifier.
When an external device is connected through the AUX jack, the incoming analog audio signal is routed into the speaker's audio path and then toward the amplification stage.
Depending on the exact PCB design and switching arrangement, inserting the AUX plug may change the active input path. Therefore, the practical behaviour should be verified directly on the board rather than assuming that every revision uses an identical switching circuit.
For repair, inspect the AUX jack for broken contacts, damaged solder joints, oxidation, and mechanical stress. A common fault is intermittent audio caused by a cracked solder joint around the jack.
ft2920P Audio Amplifier IC.
The main reported power amplifier IC in the boAt Stone 1000 circuit is ft2920P.
The supplied information lists:
IC Number: ft2920P
Other Marking: 200512
Total Pins: 24
Reported Output Rating: 8 watts
Reported Efficiency: 82%
Amplifier Class: Class G Boost
The amplifier is one of the most important components on the PCB because it converts the relatively low-level audio signal from the Bluetooth or AUX section into a stronger signal capable of driving the speaker.
Working Principle of the ft2920P.
The supplied description identifies the ft2920P as a Class G amplifier with boosted power operation.
In a power-efficient amplifier design, the circuit attempts to use the available supply energy effectively so that less power is unnecessarily converted into heat.
The audio input enters the amplifier through its signal input stage. The IC then processes and increases the signal while the output stage provides the required drive current and voltage for the connected speaker.
The actual output power depends on several factors, including supply voltage, speaker impedance, PCB design, thermal conditions, and the limits of the amplifier IC itself. Therefore, an advertised wattage should not be treated as a guaranteed output under every operating condition.
How the ft2920P Handles Loud Audio.
When the audio level increases, the amplifier must deliver more output power to the speaker.
A properly designed power amplifier manages this by controlling the output stage and available supply rails. Efficiency becomes especially important at higher volume because greater audio power naturally increases current consumption.
If the supply voltage drops excessively, the speaker may produce distortion, crackling, or sudden shutdown. This can be caused by a weak battery, damaged power components, high-resistance connections, or an amplifier stage operating outside its normal conditions.
Heat Dissipation in the Amplifier Section.
Every power amplifier produces some heat during operation.
Better efficiency means that a larger proportion of the supplied energy is converted into useful audio output rather than unwanted heat. The PCB copper area, package design, enclosure ventilation, and mechanical mounting also contribute to thermal performance.
If the amplifier IC becomes abnormally hot at low or medium volume, the problem should not be ignored. A shorted output component, damaged speaker, incorrect supply voltage, or faulty IC may be responsible.
PT2308-S Headphone Driver IC.
The reported headphone driver IC is PT2308-S, marked with 1DE4A8 as another number.
The supplied information identifies it as an 8-pin IC used for the headphone output path.
Headphone Driver Function.
A headphone load requires a different type of drive arrangement from a large speaker.
The headphone driver section provides an appropriate audio signal for the headphone output while avoiding the need to use the main high-power speaker amplifier to directly drive a headphone load.
For repair, check the headphone jack contacts, signal traces, nearby coupling capacitors, and the supply voltage around the PT2308-S section.
If the speaker works normally but the headphone output has no sound, the problem can be isolated by checking whether the audio signal reaches the driver input and whether the driver receives its required supply.
4056A Charging IC and Micro USB Section.
The charging circuit uses a reported 4056A 8-pin charging IC with the marking 0rB20H.
Its purpose is to manage the charging process from the 5V Micro USB input and regulate the current delivered to the rechargeable battery according to the charging circuit design.
Charging Circuit Working Principle.
The Micro USB connector provides the external 5V charging supply.
That input reaches the charging section, where the 4056A and associated components control the battery charging process.
A typical single-cell lithium battery charging circuit uses a controlled charging profile rather than simply connecting a 5V source directly to the battery. The charging controller therefore plays an important safety and battery-management role.
The actual charging current depends on the resistor configuration, charger IC implementation, PCB revision, thermal conditions, and battery specification.
Charging LED Indicator.
The supplied information reports a red LED during charging.
LED behaviour can vary by circuit revision, but a red indicator is commonly used to show an active charging state. Other reported indicators include blue, red, and green LEDs for operating or Bluetooth-related states.
During repair, measure the charging input voltage at the Micro USB connector first. Then check the charging IC input and battery-side voltage.
Transistors: J3Y and A119V.
Two transistor markings are reported on the PCB:
J3Y and A119V.
Both are three-pin transistor devices, but the exact circuit function must be determined from their surrounding components and PCB traces.
A transistor in this type of portable audio system can be used for switching, signal control, biasing, muting, protection, or other low-power control functions.
J3Y Transistor.
The J3Y marking is commonly associated with a small-signal NPN transistor family.
In this speaker circuit, it may be used in switching or signal-control duties. The exact function should be confirmed by tracing its collector, base, and emitter connections on the physical PCB.
A119V Transistor.
The A119V marking may also serve a switching or control function depending on the implementation.
It should not automatically be classified as part of a traditional Class AB amplifier without confirming the surrounding circuitry. Component markings alone are not enough to determine the complete circuit role.
Four Push Switches and Control Circuit.
The boAt Stone 1000 uses four push switches for user control.
The supplied functions are:
Power On/Off
Volume +
Volume -
Mode or MP3 Next
These buttons are connected to the control logic and allow the user to operate the speaker without using a phone for every function.
Power Button.
The power switch activates or disables the main control system.
A failure here can prevent the complete speaker from starting, even when the battery is fully charged. Check the switch contacts, nearby transistor or controller circuitry, and the power rail before assuming that the main PCB is defective.
Volume Buttons.
The Volume + and Volume - buttons send control inputs to the speaker's control section.
If the buttons fail but Bluetooth audio remains functional, the problem is more likely to be related to the switch contacts or control circuit rather than the power amplifier itself.
Mode and Next Function.
The mode or next button can be used to change input modes or control playback depending on the firmware and specific board configuration.
An issue with this switch can result in incorrect input selection, unexpected mode changes, or the inability to move between available source modes.
Battery and Power Supply Section.
The battery is the main energy source when the speaker is operating without external power.
The supplied script contains several battery values, including 4–7V, 5V, 300mAh, and 6A. These values should not be treated as one consistent battery specification because they conflict with the normal electrical requirements of a single-cell rechargeable lithium battery system.
For repair, the actual battery label printed on the installed cell must be used as the authoritative reference.
Battery Working Principle.
The battery supplies power to the Bluetooth module, amplifier section, control circuit, and other electronics.
The amplifier draws the highest current when the speaker is operating at higher volume. As battery voltage falls, the available output power can also decrease, and the protection circuit may eventually shut the speaker down.
This is why a speaker that works normally at full charge but becomes distorted or shuts down at low battery may have a battery or power-supply issue rather than a defective audio amplifier.
Reported Battery Backup.
The supplied information mentions up to approximately 8 hours of battery backup.
Actual playback time depends on volume level, battery condition, Bluetooth activity, amplifier efficiency, and other power-consumption factors. Battery capacity alone does not guarantee a fixed runtime.
boAt Stone 1000 Circuit Repair Guide.
A systematic troubleshooting method is safer and more effective than replacing ICs randomly.
Problem: Speaker Does Not Power On.
Start with the battery voltage.
Check the battery connector and inspect the PCB for burnt components, cracked tracks, corrosion, or broken solder joints.
Next, check the Micro USB charging input and charging circuit. If the battery is completely discharged, the charging section may need to be checked before testing the amplifier.
Also inspect the power push switch and any transistor-based power control stage.
Problem: Speaker Charges but Does Not Turn On.
If the charging LED works but the speaker remains completely dead, check whether the battery voltage rises to the expected level.
Then inspect the power-management path between the battery and main circuitry.
A faulty push switch, power transistor, controller supply, broken PCB trace, or shorted component can interrupt the power path.
Problem: Bluetooth Connects but There Is No Sound.
This is an important diagnostic condition because it indicates that the wireless section may already be functioning.
Check the following stages in order:
Bluetooth module → audio signal path → amplifier input → amplifier supply → amplifier output → speaker
A multimeter can be used to verify supply rails and continuity, while an oscilloscope or suitable audio signal-tracing method can help confirm whether the audio waveform reaches the amplifier.
Do not directly short amplifier output pins to ground during testing.
Problem: AUX Works but Bluetooth Does Not.
In this situation, the amplifier and speaker may still be functional.
Focus on the Bluetooth module, its power supply, oscillator or crystal network, pairing/control circuitry, and the audio output path from the Bluetooth section.
This type of fault is useful because the working AUX path provides a reference for the downstream amplifier circuit.
Problem: Bluetooth Works but AUX Does Not.
Check the 3.5 mm AUX jack first.
A damaged jack contact or broken solder joint is a common mechanical fault. Then inspect the input trace and any switching contacts associated with the AUX connector.
If the AUX signal reaches the amplifier input but there is still no output, the problem may exist farther downstream.
Problem: Sound Is Distorted at High Volume.
High-volume distortion can occur for several reasons.
Possible causes include a weak battery, supply-voltage drop, damaged speaker, amplifier overheating, incorrect speaker load, damaged output components, or an amplifier IC approaching its operating limit.
Test the speaker using a known-good battery and inspect the amplifier supply voltage while increasing volume gradually.
If distortion appears only when the battery becomes weak, the battery or power-delivery section deserves particular attention.
Problem: Amplifier IC Gets Very Hot.
An amplifier IC becoming excessively hot is not normal when the speaker is operating under ordinary conditions.
Check the speaker impedance, output section, supply voltage, PCB shorts, and nearby capacitors.
A partially shorted speaker coil can place additional load on the amplifier and cause abnormal heating. A damaged IC can also develop excessive internal current consumption.
Problem: Speaker Charges Slowly or Does Not Charge Fully.
Measure the voltage at the Micro USB connector first.
Then check the charging IC input, battery voltage, charging-current path, connector condition, and associated resistors.
A damaged Micro USB port can create increased contact resistance and cause unstable charging.
Practical Circuit Testing Sequence.
For board-level repair, the following sequence is more useful than replacing components without measurement:
Inspect the PCB under good lighting.
Check for burnt, cracked, corroded, or loose components.
Measure battery voltage.
Verify the 5V charging input.
Check the charging IC supply.
Confirm the main power rail.
Check whether Bluetooth pairing works.
Test the AUX input independently.
Check amplifier supply voltage.
Trace the audio signal toward the ft2920P.
Check the speaker and its wiring.
Test the headphone driver section separately if applicable.
This approach helps identify whether the fault is in the power section, input section, amplifier section, output section, or control circuit.
Important Component Reference Table.
| Section | Component | Reported Marking | Main Function |
|---|---|---|---|
| Bluetooth | Bluetooth Module | ZT-4390E5 | Wireless audio reception |
| AUX | 3.5 mm Jack | Audio Input | Wired audio input |
| Main Amplifier | Audio IC | ft2920P / 200512 | Speaker power amplification |
| Headphone | Driver IC | PT2308-S / 1DE4A8 | Headphone audio drive |
| Charging | Charging IC | 4056A / 0rB20H | Battery charging control |
| Transistor | Q Device | J3Y | Switching or signal control |
| Transistor | Q Device | A119V | Switching or control function |
| Control | Push Switches | 4 switches | Power, volume, mode/track |
| Power | Rechargeable Battery | Verify PCB label | Main energy source |
Key Points About the ft2920P Amplifier.
The ft2920P is the central audio power stage described in the supplied circuit information.
It receives audio from the upstream signal path and provides the stronger output required by the speaker.
The reported specifications identify 24 pins, approximately 8W output, 82% efficiency, and a Class G Boost architecture. These figures should be treated as board-specific reported information unless confirmed against the exact manufacturer datasheet for the fitted IC revision.
The IC can receive audio originating from either Bluetooth or AUX because both sources ultimately feed the speaker's audio path.
Important Repair Safety Notes.
Portable Bluetooth speakers commonly contain lithium rechargeable batteries. A damaged, swollen, punctured, or overheated battery should not be continued in service.
Never replace a battery with an unknown voltage or polarity.
Do not connect a lithium battery directly to a 5V charging source without the appropriate charging and protection circuit.
When checking the amplifier section, avoid creating a short circuit between output pins or between an output pin and ground.
For board-level repair, use a current-limited power supply where appropriate and confirm polarity before applying external power.
Note: Component markings and electrical values can vary between PCB revisions, so always verify the actual board and battery markings before component replacement.
Disclaimer: This guide is based on the supplied boAt Stone 1000 circuit information and general electronics repair principles; verify measurements, IC markings, battery specifications, and PCB connections on the actual unit before performing repair work.
