Seller Note “NO VISUALS”
- Board itself seems clean, can immediately see a couple of missing capacitors on one of the PCI express lanes.
- Am seeing a very shorted 5v rail (L20).
- Great to have a boardview for this board. Think there may be some innaccuracies though?
- Need to deep dive on U16 (feeds missing 5v rail).
Pre Checks / Multimeter Only
|Test / Checks||Result||Notes|
|1. Visual Inspection Eye / Magnifying Glass||Looks clean. Missing PCI lane capacitors.|
|2. Visual Inspection Microscope||–|
|3. Check for shorts on 12v PCI, 12v PCI-E, 3.3v||OK||Couldn’t find any obvious shorts.|
|4a. Resistance VCore (~0.5)||7.8Ω|
|4b. Resistance VMem (~60Ω)||62.5Ω|
|4c. Resistance 3.3v Rail (~960Ω+)||Ω|
|4d. Resistance 5v Rail (~5KΩ)||<1Ω !!!||In the boardview L20 should be the 5v inductor, resistance appears very low.|
|4e. Resistance 1v PEX Rail (~123Ω+)||120Ω|
|4f. Resistance 12v BUS (14.7kΩ )|
Power On / Test Rig Checks
|Tests / Checks||Result||Notes|
|1. Observations (e.g. PCB heat noticed, |
blank screen, power light on monitor,
bios screen, o/s loaded, artefacts, )
No heat (GPU).
|2. Voltage VCore (~0.88v)||0v|
|3. Voltage VMem (~1.4v)||0v|
|4. Voltage PEX Rail (~1v)||0v|
|5. Voltage 3.3 BUS||–|
|6. Voltage 12 Ext||–|
|7. Voltage 5v Rail||~0.45v|
|8. Voltage VDDCI||v|
|9. Voltage 1.8v||–|
Deep Dive Missing 5v Rail
The 5v rail isn’t completely missing, it is just too low at around 0.52v.
The IC that drives it is U16 (APW7142) 3A, 12V, Synchronous-Rectified Buck Converter (https://datasheetspdf.com/pdf-file/659355/AnpecElectronicsCoropration/APW7142/1).
After removing U16, the short is still there. Need to investigate the connection to U14.