ITTSB.EU Blog Forum
Electrical Metrology | Measurement Tips & Products | Calibration standards => Electrical Metrology for enthusiast => Topic started by: Kiriakos GR on August 08, 2022, 09:21:44 PM
-
Intro ..
I am starting a new project and this is conductivity measurement over ATX PSU power connectors.
Point of interest this is wire resistance along PSU wire harness the ones loaded with gold plated connector - pins.
There is the claim that gold plating this minimizing any self heating between male+female pin.
And therefore the lower contacts resistance here works as safety feature when the DC load becomes very high at high performance Computer PSU.
The second part of this story, this is that voltage rails when connection losses getting minimized, this helps at voltage stability under load.
They are out there modern PSU claiming 12V voltage rail stability at +|- 1.5% (no matter what).
Therefore it is of importance connector matting resistance to be inspected.
Along at ATX 24 pin harness, to be invented a new testing platform that will verify that all connections served by 18AWG wire, they are its one healthy and capable for maximum current transfer.
The valuable find..
I did stated web search about finding on-line any Gold plated Molex motherboard connector, and all my searches was pointing me to eBay and to fake gold plated pins.
Few years ago some one donated to me one ASUS M3N78-CM Socket AM2+ of November 2008, he gave it to me for parts or not working.
By careful inspection, ATX 24 pin connector along CPU 12V rail connector both are Gold plated. 8)
ASUS was so generous at 2008 that it did use even gold plated DC fan connector.
I did use my hot-air tool and I did remove the valuable parts. :)
The future ...
Now my head spins at crazy RPM, so me to find the best idea about making my very own, PSU connector resistance evaluator tester.
Now just imagine that 18AWG wire (at about 60cm of length) along male + female pin (Gold plated), we have a sum of 18~20 milliohm of resistance.
Therefore it is required one dedicated 4W resistance meter too.
This is not an application for using any regular multimeter.
To be continued ... ;)
-
I do understand the difficulty to get your camera lens inside the connector pins. :)
At ATX they are not tin plated, but neither of 100% shiny Gold.
You got there a rare find (Thump up) !!
-
The issue with connectors over PCB from ASUS and others, this is that there is not any MOLEX part codes over the housing.
The only clues are the one obtained due visual inspection.
Molex specification this is 30 matting cycles (max) per pin at wired connectors.
But I have not find yet any similar specification for Molex pins these for soldering over PCB.
EDIT ...
I did find it 8) https://www.molex.com/molex/products/part-detail/pcb_headers/0039289248
Part number 0039289248 Mini-Fit Family Power Connectors - Series 5566 for PCB
Durability (mating cycles max) 30
Material - Metal Brass
Gold plated
Pitch - Mating Interface 4.20mm
Temperature Range - Operating -40° to +105°C
Electrical
Current - Maximum per Contact 9.0A
Voltage - Maximum 600V
No2 CPU plug 4x https://www.molex.com/molex/products/part-detail/pcb_headers/0039289048
Identical specifications.
MOLEX Operating tests with 18 AWG wire.
Max Temp Rise Degrees C, over ambient / Ampere load
2.6 C / 2A
9.7 C / 4A
21.1 C / 6A
32.2 C / 7.5A
In conclusion at Summer time with 33 Ambient, at 7.5A both pins temperature expected to become as high as 65C ...
80C this is max of Wire insulation tolerance for continues operation.
And therefore there is an sensitive balance that it should kept, or else flames will appear.