1) I have a quad charger that is split into 4 separate sections and one section doesn’t charge anymore. I have located what I think is a thermistor and on the shrink tube it says 125degrees C. I cut the shrink tube and it looks like a 0.33 ohms fusible(?) resistor. Behind the heat shrink it’s a resistor with color code9 orange, orange, silver, gold and a green circle on top for the 5%) So it is 0.33ohms. So, it should test at 0.3-0.4 ohms, instead it tests full opened. Please let me know where I can find this. I wish I could show pics. Thanks
2) The second component is an IC with 6 pins marked 85A50D on it and it has a U on the PCB. The ground pin is 6 and from ground to pins 1,2 and 3 it shows diode voltage drop. Pin 2 shows 15.93V pin3 shows 0.04V pin 4 shows 1.3V pin 5 shows 1.15V. Pin 1 has a little marking dot above it. I have no clue where to find this tried every available source and no data on this. I know there is a way to find it based on measurements. it measures 2.8mm by 1.5mm. The depth is probably 1mm or below. Please help me out with this.
@gica69 Hi, the package of the IC is ”extremely likely” to be an SOT-23-6. The silk screen U1 indicates an IC (not diodes or transistors). it is closely surrounded by a diode D5 (likely a Schottky for switching output), 2 resistors (474 and 472) likely part of a feedback voltage divider. A nearby ceramic cap and inductor trace resembles a step-down (buck) switching regulator layout. In this context the 85A50D is almost certainly a rebranded or house labelled version of an AP3012 (by Diodes Inc. or clones like XL Semi, Joulwatt, or Ruilong). The AP3012 application would be chargers, led drivers regulators etc etc. The pinout functions for each pin individually would be : Pin 1: SW (switch node to diode D5 in your case), Pin 2: VIN (15.93 in your case), Pin 3: EN or NC (likely inactive in your case), Pin 4: GND, Pin 5 FB (1.15V to resistor dividers in your case) and finally Pin 6: COMP / SS (1.3V -to a small cap in your case). So the official part number would be AP3012KTR-E1. Another compatible part would be a pin-compatible clone called : AX3002. Some similar clones would be JW5026 or XL1509 but watch the MAX. Vin rating ! Just make sure that Vin does not exceed 18V or go for a 24V (rated clone) like the AX3002. As for the interrupted part (with colour bands) what you’re seeing likely is a fusible resistor or possibly a PTC thermistor (resettable fuse).
Now, The colour code (orange-orange-silver-gold green) does indeed correspond to 0.33Ω ±5%. However I don’t know if you’ve noticed but the green band looks to be thicker than all other ones. This may be a manufacturer’s marking or indicate a special characteristic (e.g., fusible or thermal rating).
The “125°C” on the shrink tube may be indicating the temperature rating or the fuse trip temperature. Some fusible resistors or thermal protectors are rated to blow or open circuit when the temperature reaches that level.
And obviously since it’s open now, it almost certainly means it’s failed (likely to protect the circuit or due to a fault downstream). This would explain why that particular charging output is dead. I hope the above helps and…Good Luck.
Welcome! Sounds like you are off to a good start. Luckily, you have the next best thing to schematics, identical supplies. Compare the bad area to the others to give you a better idea of what everything should look like. Once you figure that out, try to match up parts. Looks like Ovi has you in the right direction there.
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