im working on this amp and it has an issue with the output circuit. all the fets and gate resistors are good but cant find the problem. im at a loss
Attached Files
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Hey everyone,
I'm currently working on a mid-70s Sharp Electronic Digital Clock Radio, Model FY-70CH. I found the service manual online, printed it out, and have been studying it for a while. My main reasons for tackling this are: (1) I want to learn electronics and figured I'd start with something I had on hand, and (2) I want to fix its issues. Right now, the radio sounds awful, has about 5V DC at the speaker terminals, and the alarm time setting doesn't work. But I'm not asking how to fix these problems.
Instead, here's what's been bugging me so far:
The schematic... -
I am having some trouble with troubleshooting a Asus X532FL rev 2.0 motherboard, which does not power on. So at the first MOSFET, I am getting 19V at the drain, and then 3.2V on both gate and source (compared with ground). Of course, the 2nd MOSFET's source will have 3.2v at source.
First MOSFET is a QM3056M6 and 2nd MOSFET is a QM0930M3
I already checked first MOSFET and source and gate are not shorted (drain with source not shorted either). Also I have 1.7V at the LDO rail (measured at the keyboard connector, as the power button is on the keyboard).
First... -
Hello everyone, I have an ASUS FX506LI laptop that does not turn on, and I need help diagnosing the issue. Here is what I have checked so far:
Initial Symptoms:- The laptop has no power at all (no LEDs, no fan spin).
- No 3.3V or 5V present on the board.
- The power button (NBSWON#) reacts but only changes from 0V to 0.5-0.11V.
- Charger input (FETs PKCH2BB)
- Drain: 20V, Source: 0V, Gate: 0V (FETs not switching).
- BQ24780S Charger IC:
- VCC and ACDET are present.
- ACN / ACP, ACDRV, BATDRV, LODRV, HIDRV, ACOK, SRN, SRP – all 0V.
- Shunt resistor has 10Ω to ground.
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Hi All - I'm in the midst or reprogramming the bios on my gen1 Surface Laptop Studio and I accidentally blew away 2 resistors nearby the bios. I don't have another board to measure values of the missing resistors and schematics aren't available, bbut the bios is a 6x5mm Winbond WSON8, W25R256JWPQ model. The traces are conductive to Pins 3 and 7 (IO2 & IO3 respectively) so I have reason to believe they are 10k pull up resistors since IO2&3 pins are used for Quad SPI instructions.
Does anyone with more knowledge, and experience than I, know if this is the case?
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Hi Folks
This has to do with a LED light driver rated for Output - DC36-65V 300mA. This is used to drive a 15W LED panel light.
Now this does not work so opened up and found 2 resistors burnt to crisp. Sensing a learning moment, i looked around the circuit to figure out that it is built around the OB2538 chip. The circuit to a large extent follows the sample application circuit mentioned in the data sheet. I have traced the actual circuit and the same is also attached for reference.
But i have some queries on this circuit
1. The resistors that burnt to crisp...
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