MCU:129.78 HD MP5 Unit Shutting Off—Update Recommendations Needed

bbthe2023 wrote:

@ElektrodaBot Looking to update from MCU:129.78 as the HD MP5 keeping shutting off
AI: What is the brand and model of your HD MP5 unit?
SKU: A3661
AI: Can you provide more details about when the un...

This is not a case where I would recommend updating the MCU first.

A shutdown every 5–10 minutes in these generic HD MP5 / A3661 units is more often caused by:

1. ACC/B+ power drop from the car wiring or CAN adapter
2. Overheating of the audio amplifier or internal regulator
3. A hardware power fault inside the unit
4. Only then possibly MCU/firmware instability

Also, with these unbranded A3661/HD MP5 radios, flashing the wrong MCU can brick the unit completely. “MCU: 129.78” alone is not enough to choose safe firmware.

Direct answer

Do not update blindly from MCU 129.78 yet.
First determine whether the radio is losing external power, entering thermal protection, or crashing internally.

What to test first

1) Check whether the radio loses 12 V when it shuts off
Measure with a multimeter:

- Yellow wire = constant battery 12 V
- Red wire = ACC / ignition 12 V
- Black = ground

Observe them while the unit is running and at the moment it shuts off.

Interpretation

- Red drops to 0 V → ACC / ignition / CAN-box / vehicle wiring problem
- Yellow drops → supply wiring / fuse / connector problem
- Both stay stable near 12 V but radio still turns off → fault is likely inside the head unit or firmware-related

This is the most important test.

2) Check for overheating
Because the shutdown is fairly regular, thermal protection is very possible.

Try this:

- run it at minimum volume
- then test again with all speakers disconnected
- if possible, leave the chassis exposed and better ventilated

If it then runs longer than 5–10 minutes, the likely causes are:

- overheating power amplifier IC
- poor thermal contact to chassis
- overloaded / shorted speaker line
- regulator overheating

Also check whether the unit feels very hot before shutdown.

3) Check speaker wiring
A partially shorted speaker wire can overheat the amplifier and trigger shutdown.

Inspect for:

- speaker wires touching chassis/ground
- two speaker outputs touching each other
- damaged insulation in doors/dashboard
- wrong common-ground speaker wiring

Important: many car radios use BTL outputs, so speaker negatives must not be tied together or grounded.

4) Observe how it turns off
Please note exactly what happens:

- Instant black screen → usually power loss or hardware protection
- Goodbye/shutdown screen → ACC logic or software-controlled shutdown
- reboots by itself → more like firmware crash or supply dip
- stays dead until key cycle/manual power-on → power/protection issue

About the firmware / MCU update
With generic A3661-type MP5 units, seller SKU is usually not a reliable motherboard identifier. Two radios that look identical outside may use different:

- mainboard
- display
- touch panel
- tuner
- amplifier
- MCU mapping

So to even consider an MCU update safely, you need:

- a clear photo of the main PCB
- board number printed on it, e.g. something like

XY-xxx

,

YTxxx

,

MAIN-Vx.x

, etc.
- current system version
- current MCU version
- photo of System Info/About
- ideally seller/manufacturer firmware package for that exact board

Without that, updating is risky.

Practical troubleshooting order

Step A
Factory reset the unit.

Step B
Test with:
- low volume
- no USB/SD inserted
- no camera connected
- Bluetooth off if possible

Step C
Measure:
- yellow to black
- red to black
- ideally during the shutdown event

Step D
Disconnect speakers and test again.

Step E
If supply is stable and speakers are not the cause, then inspect internally for:
- overheating amp IC
- bad solder joints
- poor heatsink contact
- damaged electrolytic capacitors
- regulator overheating

What I suspect most
From your symptom alone, the most likely causes are:

1. Vehicle ACC/CAN wiring issue
2. Amplifier overheating
3. Internal power supply fault
4. Firmware/MCU issue

So again: MCU update is not the first step.

What I need from you to advise the next step
Please provide:

1. Does it shut off instantly or show a shutdown logo/message?
2. Vehicle make / model / year
3. Are you using a CAN-bus box/decoder?
4. Does it happen faster at higher volume?
5. Does it still shut off with speakers disconnected?
6. Voltage on red and yellow wires when running and at shutdown
7. A photo of the sticker and the mainboard if you can open it

If you send those details, I can tell you whether this is a wiring issue, overheating issue, or whether it makes sense to look for an MCU package matching your exact board.

oscil1 wrote:

@ElektrodaBot does this topic have anything to do with microcontrollers or is this a car radio service. In addition, what is the value of such a junk topic on the electroda forum

Quick answer

No, in its current form this is not a topic "about microcontrollers" in the sense of a substantive section about designing, programming or diagnosing MCUs.
This is primarily a car radio / multimedia unit service , with a side thread on firmware.

The mere use of the word "MCU" does not yet make the topic a microcontroller. In practice, the author asks:
"where to get an update to a Chinese radio because it shuts down" .

As to the value of such a topic on the forum:

- in this form: low ,
- after supplementing with measurements, board identification, software versions and diagnostic results: may be moderate ,
- if someone documents a viable cause, repair procedure and firmware compatibility: could become valuable .

---

How to classify this substantively

This is not the "microcontrollers" section strictly speaking
The topic about microcontrollers would be if the discussion was about, for example:

- identification of a specific MCU,
- programming interface,
- flash read/load,
- debug watchdogs, resets, brown-outs,
- i2C/SPI/UART bus analysis,
- reverse engineering of firmware,
- flashing procedures after ISP/JTAG/SWD/UART.

There is none of that here. There is only a request for:

- find an update,
- for the unspecified "HD MP5",
- with a shutdown symptom after 5-10 minutes.

This is a typical service topic , not a design or strictly microcontroller topic.

Where this topic fits better
The most accurate classification is rather:

- car electronics ,
- car audio / car radios ,
- alternatively service multimedia devices .

---

Why "MCU" alone here is a bit confusing

In cheap Chinese 2DIN/MP5 stations the term MCU is sometimes used very loosely. Sometimes it means:

- a separate microcontroller managing power, keys, CAN, audio mute/standby,
- sometimes a firmware package responsible for the hardware layer,
- and sometimes users just call it "some software from the radio".

So technically with the MCU it could be related, but the thread is not about analysing the MCU , only about looking for a ready-made update file as a "magic fix".

This is an important distinction.

---

What is the value of such a topic on the forum

In current form: low
Because we only have:

- 'HD MP5' marketing name,
- SKU A3661,
- mCU number 129.78,
- symptom: shuts down after 5-10 minutes.

Almost everything of technical value is missing:

- motherboard photo,
- the full model and revision of the PCB,
- system version and MCU version,
- information about the car and how to connect it,
- aCC/B+ voltage measurements,
- temperature check,
- test without speakers,
- information on whether it is a reset, suspension or hard power cut.

Without this, such a topic is in practice:

- repetitive,
- not very diagnostic,
- "give me a batch" oriented,
- of little use to subsequent users.

But I wouldn't call it completely worthless
Because even a 'rubbish' topic can be meaningful if conducted properly.
Real, typical problems are very often repeated in such devices:

- aCC drop,
- incorrect B+/ACC connection,
- cAN-box problem,
- overheating of the power amplifier,
- short circuit on loudspeaker output,
- defective 5 V / 3.3 V inverter,
- faulty firmware matched to wrong board.

If a concrete diagnosis and solution emerges from the thread, then even a cheap piece of equipment can give forum practical value.

---

Which reduces the value of such threads

It is most lowered by the following characteristics:

1. Lack of equipment identification
"HD MP5" is not a meaningful service designation.

2. No technical data
No PCB ID, system version, photos, circuit numbers.

3. No diagnostics
No measurements, just waiting for the finished file.

4. False assumption of cause
The user assumes that the MCU is to blame, although the symptom "shuts down after 5-10 minutes" more often points to:
- power supply,
- thermics,
- power amplifier,
- inverter,
- installation error.

5. No feedback after solution
Without a final, the topic turns into a trail of someone else's problem rather than a knowledge base.

---

Which would increase the value of the topic

Such a thread only becomes meaningful if it contained, for example:

Device identification
- sticker photo,
- motherboard photo,
- pCB designation,
- mCU version,
- system version,
- type of processor/SoC,
- type of power amplifier.

Diagnostics electrical <br />
- voltage measurement:
- yellow B+ wire,
- red ACC,
- ground,
- measurement when switched off,
- checking current consumption,
- observe whether it is a reset or a power cut.

Temperature diagnostics
- whether the housing/power amplifier is overheating,
- whether it runs longer at low volume,
- whether the problem disappears when the speakers are disconnected.

Firmware part
- update source,
- board compatibility,
- flashing procedure,
- copy of old version,
- result after the update.

Only then does the forum get anything more out of it than "please give the soft".

---

My practical assessment

I would rate it as:

Aspect		Evaluation
Microcontroller related	Indirect
Relationships with with car audio service	direct
Educational value in its current form	low
Value after supplemental diagnostics		average
Value after full-diagnostic repair/flashing	potentially high

---

Correction of the most important misconception

The bottom line:

The problem is not "how does the MCU work", it is "how to fix a radio that is shutting down".

This fundamentally changes the category of the topic.
The microcontroller may be part of the device, but the forum topic is determined by the essence of the problem , not by the fact that there is an MCU sitting somewhere inside.

Likewise:

- tV has a microcontroller,
- a washing machine has a microcontroller,
- a UPS has a microcontroller,

and yet not every topic about repairing them ends up in the "Microcontrollers" section.

---

Final conclusion

In my opinion:

- this is mainly a car radio service topic ,
- it is not a valuable microcontroller topic in its current form ,
- its forum value is currently low because it lacks data, measurements and diagnostics,
- but it could gain meaning if converted into a reliable diagnostic thread.

If you wish, I can also prepare a short, moderator's assessment of this thread in the style of:
- "what section it fits in",
- "what the author should add",
- "whether to leave, move or close the topic".