Repair of Bose GS1E66920A Amplifier Mazda 6

🛠️ BOSE Amplifier Issue in Mazda 6 GH: Causes and Repair

A well-known issue in the Mazda 6 GH (and other Mazda models equipped with the BOSE sound system) is the appearance of crackling sounds in the speakers, intermittent audio dropouts, and eventually complete failure of the amplifier, which is located under the front passenger seat.

🔍 Root of the Problem

The amplifier uses a dual voltage regulator, the ST2L05-3300PT, which outputs two voltages:

• 1.25 V for powering the main processor;

• 3.3 V for other circuit components.

Over time, this regulator can malfunction — the 1.25 V line may suddenly jump to 3.3 V, which damages the processor — the SCB56374AEB chip.

What happens:

• Initially, the processor goes into protection mode — the sound disappears temporarily.

• Later, intermittent crackling appears in the speakers.

• Eventually, the processor burns out, and the amplifier stops working completely.

💡 Solution

The ST2L05-3300PT is rare and hard to find, but it can be replaced with two separate linear regulators, making the system much more reliable.

🔁 Replacement:

Instead of ST2L05-3300PT, use:

• LD1117S-1.2TR — provides 1.2 V (equivalent to 1.25 V);

• KF33BDT-TR or LD1117S33TR — provides 3.3 V.

Both chips are available in SOT-223 packages, which are easy to mount.

🧰 Repair steps:

1. Remove the amplifier from the car.

2. Open the casing and desolder the ST2L05-3300PT.

3. Solder in two separate regulators:

   • Feed 5V to their inputs.

   • Route the outputs to the 1.25 V and 3.3 V lines.

   • Add ceramic or tantalum capacitors (10 µF recommended).

4. Test the amplifier without load, then with speakers.

5. Reinstall the amplifier into the car.

💰 Cost:

The total cost is less than $1, and it can prevent expensive repairs or complete failure of the processor if caught early.

Tags: Bose, amplifier, Mazda 6, GS1E66920A, repair, OEM audio, car audio, original module