DRCY X #9

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opened 2026-08-04 15:43:50 +00:00 by allspice-thomas · 0 comments

allspice-thomas commented

2026-08-04 15:43:50 +00:00

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[🚨 Error] Component Q13B, pin 5: Drain 2 is incorrectly connected directly to VFAN power supply instead of a switched output net. This prevents Fan 4 from being controlled, causes LED4 to be non-functional, and would create a short circuit from VFAN to GND when the MOSFET turns on.

Pin 5 is the Drain 2 terminal according to the datasheet (from datasheet NCV8402ADDR2G, page 1)
Pin 5 is connected to the VFAN net (from schematic)
VFAN is the positive power supply rail for the fans (from schematic)
In a low-side switch configuration, the drain should be connected to the load, not to the power supply (reasoning)
The other three channels (Q12A, Q12B, Q13A) all have their drains connected to switched output nets that drive fan connectors and LEDs (from schematic)
Q12A pin 7 connects to NetC154_2 (J29 pin 1, LED1 cathode, C154 pin 2) (from schematic)
Q12B pin 5 connects to NetC153_2 (J22 pin 1, LED2 cathode, C153 pin 2) (from schematic)
Q13A pin 7 connects to NetC211_2 (J31 pin 1, LED3 cathode, C211 pin 2) (from schematic)
J30 pin 1 (Fan 4 connector negative terminal) is connected directly to VFAN instead of to a switched output (from schematic)
J30 pin 2 (Fan 4 connector positive terminal) is also connected to VFAN (from schematic)
With both fan connector pins at VFAN, the fan cannot be switched on or off (reasoning)
LED4 cathode is connected to VFAN (from schematic)
LED4 anode connects through R14 to VFAN (from schematic)
With both LED4 terminals at VFAN potential, there is no voltage drop across the LED and it cannot light up (reasoning)
C209 has both pins connected to VFAN, providing no filtering function (from schematic)
When Q13B gate is driven high, the MOSFET will turn on and attempt to pull VFAN to GND through the low RDS(on) of 165mΩ typical (from datasheet NCV8402ADDR2G, page 3)
This will cause excessive current flow limited only by the NCV8402's internal current limiting (from datasheet NCV8402ADDR2G, page 3)
The current limit is specified as 3.7-5.0 A at VGS=5V or 4.2-5.4 A at VGS=10V (from datasheet NCV8402ADDR2G, page 3)
This configuration wastes power, may cause thermal issues, and will trigger the device's self-protection features (reasoning)
The datasheet shows typical application with drain connected to the load, not to the power supply (from datasheet NCV8402ADDR2G, page 1)
Pin 5 should be connected to a new switched output net (similar to NetC154_2, NetC153_2, or NetC211_2) along with J30 pin 1, LED4 cathode, and C209 pin 2 (reasoning)
This connection error makes the Fan 4 control circuit completely non-functional (reasoning)

All affected pins

Component Q13B, pin `5`: Drain 2 is incorrectly connected directly to VFAN power supply instead of a switched output net. This prevents Fan 4 from being controlled, causes LED4 to be non-functional, and would create a short circuit from VFAN to GND when the MOSFET turns on.

Pin 5 is the Drain 2 terminal according to the datasheet (from datasheet NCV8402ADDR2G, page 1)
Pin 5 is connected to the VFAN net (from schematic)
VFAN is the positive power supply rail for the fans (from schematic)
In a low-side switch configuration, the drain should be connected to the load, not to the power supply (reasoning)
The other three channels (Q12A, Q12B, Q13A) all have their drains connected to switched output nets that drive fan connectors and LEDs (from schematic)
Q12A pin 7 connects to NetC154_2 (J29 pin 1, LED1 cathode, C154 pin 2) (from schematic)
Q12B pin 5 connects to NetC153_2 (J22 pin 1, LED2 cathode, C153 pin 2) (from schematic)
Q13A pin 7 connects to NetC211_2 (J31 pin 1, LED3 cathode, C211 pin 2) (from schematic)
J30 pin 1 (Fan 4 connector negative terminal) is connected directly to VFAN instead of to a switched output (from schematic)
J30 pin 2 (Fan 4 connector positive terminal) is also connected to VFAN (from schematic)
With both fan connector pins at VFAN, the fan cannot be switched on or off (reasoning)
LED4 cathode is connected to VFAN (from schematic)
LED4 anode connects through R14 to VFAN (from schematic)
With both LED4 terminals at VFAN potential, there is no voltage drop across the LED and it cannot light up (reasoning)
C209 has both pins connected to VFAN, providing no filtering function (from schematic)
When Q13B gate is driven high, the MOSFET will turn on and attempt to pull VFAN to GND through the low RDS(on) of 165mΩ typical (from datasheet NCV8402ADDR2G, page 3)
This will cause excessive current flow limited only by the NCV8402's internal current limiting (from datasheet NCV8402ADDR2G, page 3)
The current limit is specified as 3.7-5.0 A at VGS=5V or 4.2-5.4 A at VGS=10V (from datasheet NCV8402ADDR2G, page 3)
This configuration wastes power, may cause thermal issues, and will trigger the device's self-protection features (reasoning)
The datasheet shows typical application with drain connected to the load, not to the power supply (from datasheet NCV8402ADDR2G, page 1)
Pin 5 should be connected to a new switched output net (similar to NetC154_2, NetC153_2, or NetC211_2) along with J30 pin 1, LED4 cathode, and C209 pin 2 (reasoning)
This connection error makes the Fan 4 control circuit completely non-functional (reasoning)

Component LED4, pin `C`: Cathode is incorrectly connected directly to VFAN power rail instead of to Q13B drain. This creates zero voltage difference across the LED since the anode is also connected to VFAN through R14, preventing the LED from ever illuminating. The cathode should be connected to Q13B drain (pin 5) to match the working configuration of LED1, LED2, and LED3.

Pin C (Cathode) is connected directly to net VFAN (from schematic)
Pin C is the Cathode connection per the datasheet (from datasheet 5988110107F)
The anode is connected to VFAN through R14, making both terminals at the same potential (from schematic)
For an LED to conduct, the anode must be at a higher potential than the cathode by at least the forward voltage drop (from datasheet 5988110107F)
With both terminals at VFAN potential, there is zero voltage across the LED and no current will flow (reasoning)
LED1, LED2, and LED3 all have their cathodes connected to the drain of their respective low-side MOSFET drivers (Q12A pin 7, Q12B pin 5, Q13A pin 7) (from schematic)
Q13B pin 5 (Drain) is connected to VFAN instead of to LED4 cathode, breaking the expected circuit pattern (from schematic)
J30 pin 1 is also connected to VFAN, whereas J29, J22, and J31 pin 1 are connected to their respective LED cathode and driver drain nets (from schematic)
The correct configuration would be: LED4 cathode connected to Q13B drain (pin 5), forming a switched node that can be pulled to ground when Q13B is activated (reasoning)
This error prevents LED4 from functioning as a fan status indicator (reasoning)

Component J30, pin `1`: Pin 1 is incorrectly connected to VFAN instead of to a switched ground output from Q13B. This is a critical routing error that prevents Fan 4 from operating because the fan has no ground return path. With both pins 1 and 2 at VFAN potential, there is no voltage difference to drive current through the fan motor.

Pin 1 is connected to net VFAN (from schematic)
Q13B drain (pin 5) is also incorrectly connected to VFAN instead of to a switched output net (from schematic)
Q13B is part of the NCV8402AD dual low-side driver with pin 3 (source) connected to GND and pin 4 (gate) connected to control signal NetQ13_4 (from schematic)
For Fans 1, 2, and 3, pin 1 of their respective connectors (J29, J22, J31) is correctly connected to switched ground outputs (NetC154_2, NetC153_2, NetC211_2) (from schematic)
Q13A (the other half of the same dual driver as Q13B) correctly has its drain (pin 7) connected to switched output NetC211_2 which goes to J31 pin 1 (from schematic)
Q12A and Q12B (the other dual driver) also correctly have their drains connected to switched outputs that go to J29 pin 1 and J22 pin 1 respectively (from schematic)
LED4 cathode is incorrectly connected to VFAN instead of to a switched output, which prevents the LED from lighting and is inconsistent with LED1, LED2, and LED3 (from schematic)
Capacitor C209 has both pins connected to VFAN, which is inconsistent with C154, C153, and C211 that have one pin on VFAN and the other on the switched output (from schematic)
The control signal path from Fan4 through buffer U2A and gate resistor R181 to Q13B gate is correctly implemented, indicating this is a routing error rather than an intentional design difference (from schematic)
In a low-side driver configuration, the MOSFET drain must connect to the load (fan ground return) and the source must connect to ground to provide a switched ground path (reasoning)
Standard 3-wire PC fans require pin 1 to be ground for the fan motor to operate (reasoning)
With both J30 pins 1 and 2 at VFAN potential, there is no voltage difference across the fan motor, preventing any current flow and fan operation (reasoning)
Pin 1 should be connected to Q13B drain (pin 5), LED4 cathode, and C209 pin 2 on a switched output net (such as NetC209_2), similar to the other three fan circuits (reasoning)

Datasheets: 📄 LED4 📄 J30 📄 Q13B

_{Replace a datasheet: 📤 J30 📤 LED4 📤 Q13B}

Originally posted by @DRCY in https://hub.allspice.io/AllSpice-Demos/Altium-Demo-Project/pulls/5/files#diff-41108d21273198ed8c5983ec6b585df21600e8f7-issuecomment-47912

[🚨 Error] **Component `Q13B`, pin `5`: Drain 2 is incorrectly connected directly to VFAN power supply instead of a switched output net. This prevents Fan 4 from being controlled, causes LED4 to be non-functional, and would create a short circuit from VFAN to GND when the MOSFET turns on.** !thumbnail[](Fans.SchDoc){ diff="AllSpice-Demos/Archimajor-DRCY-Demo:9ecce85a87495918c7559a01f7af99f93647b863...b09435216bda90650e7fdf6b009674871e52ddc7" pr="5" diff-visibility="full" variant="default" view-coords="63.06,56.24,70.56,63.74" aspect-ratio="1.29" } - Pin 5 is the Drain 2 terminal according to the datasheet *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=1>), page 1)* - Pin 5 is connected to the VFAN net *(from schematic)* - VFAN is the positive power supply rail for the fans *(from schematic)* - In a low-side switch configuration, the drain should be connected to the load, not to the power supply *(reasoning)* - The other three channels (Q12A, Q12B, Q13A) all have their drains connected to switched output nets that drive fan connectors and LEDs *(from schematic)* - Q12A pin 7 connects to NetC154_2 (J29 pin 1, LED1 cathode, C154 pin 2) *(from schematic)* - Q12B pin 5 connects to NetC153_2 (J22 pin 1, LED2 cathode, C153 pin 2) *(from schematic)* - Q13A pin 7 connects to NetC211_2 (J31 pin 1, LED3 cathode, C211 pin 2) *(from schematic)* - J30 pin 1 (Fan 4 connector negative terminal) is connected directly to VFAN instead of to a switched output *(from schematic)* - J30 pin 2 (Fan 4 connector positive terminal) is also connected to VFAN *(from schematic)* - With both fan connector pins at VFAN, the fan cannot be switched on or off *(reasoning)* - LED4 cathode is connected to VFAN *(from schematic)* - LED4 anode connects through R14 to VFAN *(from schematic)* - With both LED4 terminals at VFAN potential, there is no voltage drop across the LED and it cannot light up *(reasoning)* - C209 has both pins connected to VFAN, providing no filtering function *(from schematic)* - When Q13B gate is driven high, the MOSFET will turn on and attempt to pull VFAN to GND through the low RDS(on) of 165mΩ typical *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=3>), page 3)* - This will cause excessive current flow limited only by the NCV8402's internal current limiting *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=3>), page 3)* - The current limit is specified as 3.7-5.0 A at VGS=5V or 4.2-5.4 A at VGS=10V *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=3>), page 3)* - This configuration wastes power, may cause thermal issues, and will trigger the device's self-protection features *(reasoning)* - The datasheet shows typical application with drain connected to the load, not to the power supply *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=1>), page 1)* - Pin 5 should be connected to a new switched output net (similar to NetC154_2, NetC153_2, or NetC211_2) along with J30 pin 1, LED4 cathode, and C209 pin 2 *(reasoning)* - This connection error makes the Fan 4 control circuit completely non-functional *(reasoning)* <details> <summary>All affected pins</summary> <details> <summary>Component <code>Q13B</code>, pin `5`: Drain 2 is incorrectly connected directly to VFAN power supply instead of a switched output net. This prevents Fan 4 from being controlled, causes LED4 to be non-functional, and would create a short circuit from VFAN to GND when the MOSFET turns on.</summary> - Pin 5 is the Drain 2 terminal according to the datasheet *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=1>), page 1)* - Pin 5 is connected to the VFAN net *(from schematic)* - VFAN is the positive power supply rail for the fans *(from schematic)* - In a low-side switch configuration, the drain should be connected to the load, not to the power supply *(reasoning)* - The other three channels (Q12A, Q12B, Q13A) all have their drains connected to switched output nets that drive fan connectors and LEDs *(from schematic)* - Q12A pin 7 connects to NetC154_2 (J29 pin 1, LED1 cathode, C154 pin 2) *(from schematic)* - Q12B pin 5 connects to NetC153_2 (J22 pin 1, LED2 cathode, C153 pin 2) *(from schematic)* - Q13A pin 7 connects to NetC211_2 (J31 pin 1, LED3 cathode, C211 pin 2) *(from schematic)* - J30 pin 1 (Fan 4 connector negative terminal) is connected directly to VFAN instead of to a switched output *(from schematic)* - J30 pin 2 (Fan 4 connector positive terminal) is also connected to VFAN *(from schematic)* - With both fan connector pins at VFAN, the fan cannot be switched on or off *(reasoning)* - LED4 cathode is connected to VFAN *(from schematic)* - LED4 anode connects through R14 to VFAN *(from schematic)* - With both LED4 terminals at VFAN potential, there is no voltage drop across the LED and it cannot light up *(reasoning)* - C209 has both pins connected to VFAN, providing no filtering function *(from schematic)* - When Q13B gate is driven high, the MOSFET will turn on and attempt to pull VFAN to GND through the low RDS(on) of 165mΩ typical *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=3>), page 3)* - This will cause excessive current flow limited only by the NCV8402's internal current limiting *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=3>), page 3)* - The current limit is specified as 3.7-5.0 A at VGS=5V or 4.2-5.4 A at VGS=10V *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=3>), page 3)* - This configuration wastes power, may cause thermal issues, and will trigger the device's self-protection features *(reasoning)* - The datasheet shows typical application with drain connected to the load, not to the power supply *(from datasheet [NCV8402ADDR2G](<https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf#page=1>), page 1)* - Pin 5 should be connected to a new switched output net (similar to NetC154_2, NetC153_2, or NetC211_2) along with J30 pin 1, LED4 cathode, and C209 pin 2 *(reasoning)* - This connection error makes the Fan 4 control circuit completely non-functional *(reasoning)* </details> <details> <summary>Component <code>LED4</code>, pin `C`: Cathode is incorrectly connected directly to VFAN power rail instead of to Q13B drain. This creates zero voltage difference across the LED since the anode is also connected to VFAN through R14, preventing the LED from ever illuminating. The cathode should be connected to Q13B drain (pin 5) to match the working configuration of LED1, LED2, and LED3.</summary> - Pin C (Cathode) is connected directly to net VFAN *(from schematic)* - Pin C is the Cathode connection per the datasheet *(from datasheet [5988110107F](<https://s3-us-west-2.amazonaws.com/catsy.557/DIA_Selector_Guide_SMD_060820.pdf>))* - The anode is connected to VFAN through R14, making both terminals at the same potential *(from schematic)* - For an LED to conduct, the anode must be at a higher potential than the cathode by at least the forward voltage drop *(from datasheet [5988110107F](<https://s3-us-west-2.amazonaws.com/catsy.557/DIA_Selector_Guide_SMD_060820.pdf>))* - With both terminals at VFAN potential, there is zero voltage across the LED and no current will flow *(reasoning)* - LED1, LED2, and LED3 all have their cathodes connected to the drain of their respective low-side MOSFET drivers (Q12A pin 7, Q12B pin 5, Q13A pin 7) *(from schematic)* - Q13B pin 5 (Drain) is connected to VFAN instead of to LED4 cathode, breaking the expected circuit pattern *(from schematic)* - J30 pin 1 is also connected to VFAN, whereas J29, J22, and J31 pin 1 are connected to their respective LED cathode and driver drain nets *(from schematic)* - The correct configuration would be: LED4 cathode connected to Q13B drain (pin 5), forming a switched node that can be pulled to ground when Q13B is activated *(reasoning)* - This error prevents LED4 from functioning as a fan status indicator *(reasoning)* </details> <details> <summary>Component <code>J30</code>, pin `1`: Pin 1 is incorrectly connected to VFAN instead of to a switched ground output from Q13B. This is a critical routing error that prevents Fan 4 from operating because the fan has no ground return path. With both pins 1 and 2 at VFAN potential, there is no voltage difference to drive current through the fan motor.</summary> - Pin 1 is connected to net VFAN *(from schematic)* - Q13B drain (pin 5) is also incorrectly connected to VFAN instead of to a switched output net *(from schematic)* - Q13B is part of the NCV8402AD dual low-side driver with pin 3 (source) connected to GND and pin 4 (gate) connected to control signal NetQ13_4 *(from schematic)* - For Fans 1, 2, and 3, pin 1 of their respective connectors (J29, J22, J31) is correctly connected to switched ground outputs (NetC154_2, NetC153_2, NetC211_2) *(from schematic)* - Q13A (the other half of the same dual driver as Q13B) correctly has its drain (pin 7) connected to switched output NetC211_2 which goes to J31 pin 1 *(from schematic)* - Q12A and Q12B (the other dual driver) also correctly have their drains connected to switched outputs that go to J29 pin 1 and J22 pin 1 respectively *(from schematic)* - LED4 cathode is incorrectly connected to VFAN instead of to a switched output, which prevents the LED from lighting and is inconsistent with LED1, LED2, and LED3 *(from schematic)* - Capacitor C209 has both pins connected to VFAN, which is inconsistent with C154, C153, and C211 that have one pin on VFAN and the other on the switched output *(from schematic)* - The control signal path from Fan4 through buffer U2A and gate resistor R181 to Q13B gate is correctly implemented, indicating this is a routing error rather than an intentional design difference *(from schematic)* - In a low-side driver configuration, the MOSFET drain must connect to the load (fan ground return) and the source must connect to ground to provide a switched ground path *(reasoning)* - Standard 3-wire PC fans require pin 1 to be ground for the fan motor to operate *(reasoning)* - With both J30 pins 1 and 2 at VFAN potential, there is no voltage difference across the fan motor, preventing any current flow and fan operation *(reasoning)* - Pin 1 should be connected to Q13B drain (pin 5), LED4 cathode, and C209 pin 2 on a switched output net (such as NetC209_2), similar to the other three fan circuits *(reasoning)* </details> </details> Datasheets: [📄 LED4](https://s3-us-west-2.amazonaws.com/catsy.557/DIA_Selector_Guide_SMD_060820.pdf) [📄 J30](https://www.molex.com/pdm_docs/sd/705430001_sd.pdf) [📄 Q13B](https://www.onsemi.com/pdf/datasheet/ncv8402d-d.pdf) <sub>Replace a datasheet: [📤 J30](https://hub.allspice.io/AllSpice-Demos/Archimajor-DRCY-Demo/_upload/develop/.allspice/datasheets/0705430002) [📤 LED4](https://hub.allspice.io/AllSpice-Demos/Archimajor-DRCY-Demo/_upload/develop/.allspice/datasheets/5988110107F) [📤 Q13B](https://hub.allspice.io/AllSpice-Demos/Archimajor-DRCY-Demo/_upload/develop/.allspice/datasheets/NCV8402ADDR2G)</sub> _Originally posted by @DRCY in https://hub.allspice.io/AllSpice-Demos/Altium-Demo-Project/pulls/5/files#diff-41108d21273198ed8c5983ec6b585df21600e8f7-issuecomment-47912_