Hi all,


what are the facts / guidelines that needs to be considered while installing any expansion cards ? following are the points that I consider while installing expansion cards

1) never ignore the screws while installing n/w cards or any other expansion cards as it will cause "chip creep" - in which the cards heat up over time and cool down when the machine is turned off and they work their way out of the socket

2) make sure you never touch the connectors along the bottom for any expansion cards because any oil content in finger tips can cause damage


is there any other facts that needs to be taken account of ?

Ground yourself before touching the expansion card or the motherboard. Static electricity can cause serious damage.
Always remove the power cable from the machine.

Never remove or install cards while the system is powered. It may seem obvious but I've seen people ruin $$$ cards doing it.

one other tip, make sure the motherboard is drained of charge before trying to add the card, you can do that by pressing the power button with the system unplugged (or the switch on the back of the PSU in the off position), this ensures that any residual charge is drained from the capacitors on the board.

1 members found this post helpful.

Hi,
Look at this ATX_PSU_Schematic as a general reference (Not all designs are the same but are very similar).
Most designs for modern ATX systems will not drain the caps on board by the method you mentioned. Look at this ATX Power supply schematic, you will not drain the caps within the PSU. Switch S1 is a normally open contact (on the back of the PSU) when closed the power from the power source will be applied to the input of the PSU. Now look at the output plug pins voltage rails, that is the supply to the system. Any residual voltage after power down will decay by the PSU control circuit over time also via the system board and peripherals . The ATX voltage rails are isolated via the Power transformer. PWM IC does sense the VAC for control for a clean shutdown and control. System power on/off button is a NO(normally open) contact that controls the PSU control circuitry for on/off condition.

From experience, I have checked the Motherboard capacitors and the charge level is nil over a short time after turn off. Most of the peripheral buss are tri-state anyway. Rail capacitor(s) within the PSU do maintain a very small charge but certainly not enough to damage anything since the drain over a short period will reduce that charge by the control circuitry.

The biggest issue would be STATIC charge on the individual. One should be sure to be at the same level as the card & system, this can be done simply with a isolation static wrist strap to maintain one at the same level as the system. Usually this is nothing more than a piece of wire with a attachment strap , 10-20MΩ ohm resistor in series with the wire to isolate the user with another piece of wire attached to the opposite end of the resistor then the end of the wire has a alligator clip attached. The wrist strap will be at the same potential when the alligator clip is connected to the chassis/ground of the system. It will then be safe to work on the system.

Older AT PSU supplies could be safely drained, new ATX PSU use a low voltage sense scheme to control power on/off via the system power button. For those that want to get into a ATX_PSU, USE caution when powered on or off when the AC source is attached.

HTH!

I just want to add here that for the normal end-user there is absolutely never a need to open up a PSU. If you do so and have to do it with the AC-source attached use an isolating transformer to connect the PSU to the AC-net.

Hi,

Even with a isolation transformer, one other precaution is to use the 'one hand rule'. You would use one hand with probe to test. Power off to make any connection then power on again. Always using 'one hand' that will help prevent 'latching' or physical reaction when using two hands when one may possibly ground with the resulting action for a fault causing injury when the other hand touches live.

As to end user, the modern PSU has no user serviceable parts. At least that is what most PSU labels state. Most good technicians can replace parts but why. Most bench times for a repair of this type would exceed the cost of a new unit.

'Safety First'