I know is not probably the best place for a newbie, the AI somehow helps but I definitely prefer go with the experts. I am fascinated with the laws of electronic, but more than ever I know it demands a serious compromise to enter this amazing world. Board Description: HXYT-A0-665-REV1.1 (A bluetooth speaker)The speaker wont turn on, is doing nothing.SIDE ACompt.1= 56HS5, B310B (5 pins)Compt.2= J6 (3 pins) ?Compt.3 4004A, 33580KMSide BCompt.1= 4R7 (inductor)Compt.2= SS54 (SCHOTTKY BARRIER RECTIFIER)Compt.3= M8889, Y4D371 (8 Pins) ?Compt.4 PNSA15E7E, X0B253, 2359 --When connected the battery in the terminals, it shows normal (aprox 5V)--I tested the negative and positive spots in reverse of battery connector and off course no shorted--When first tested pin C of power button, it shows 0.840V, after some tests is showing 2.4V when first push the power button it drops to 0V but now no more drops and it gets 2.4 V no matter if push the power button--Tested all capacitors of Side A and all of them are ok, also the capacitor X which is connected to the Compt.3, the component 3 seems to be a DC-DC converter, the capacitor X is in parallel of pins 4 and 6. When checking the VIN in Compt.3 (pin5) is ok, but when I push the power button there is no VOUT (pin1)--When connected to the charger, the device’s charging led turns on and the board battery terminals shows the charging voltage. In Side B We can see the battery port, the left pin is the + one, that pin goes to the compt.1 through pad named in the image as “pad positive pin”, then the compt.1 is connected to the compt.2 (I tested both and they seem to be ok). I tested all capacitors in Side B, all of them are ok except capacitor X. The capacitor X is connected to the pin that is marked with a yellow face sticker in compt.4, and I'd like to have the PCB's information or at least the compt.4's (or the M8889) in Order to know that capacitor values.What more testing do you recommend me to apply, what is component 2 in side A, what is component 4 in side B, is it a multiplexer? What is component 3 in side B, is it a switch IC? What recommendations can you give me when is hard to find a component by its code? Attachment :  Side-A.jpg

... but may be difficult; a microcontroller + driver is great for learning but not the easiest. To find the pinout, measure resistance with a multimeter: with 3 wires, all pairwise readings should match (the three phases); with 4 wires, the pin that reads the same to all others is the neutral; phase Order only affects direction, so swap any two leads to reverse. To avoid damage, never apply DC across two leads, don’t stall the rotor, keep leads short (with a decoupling capacitor near the driver), and WAtch temperature.

I'm trying to cascade multiple 74HC595 shift registers to expand the number of digital outputs in my project. While one shift register works perfectly on its own, as soon as I add the second (and especially the third), I start getting strange or inconsistent output—some LEDs don’t light up correctly, or they shift out of Order. Is there a timing issue I might be overlooking? Do I need to delay between latching and shifting? Could signal integrity or voltage drop be the issue when chaining several ICs?