Posted 04 October 2014 - 04:09 AM

"Thank You MedEvil, Wonderful information."

I will be exploring this little gem of info for all my devices,

and then hopefully contribute to this thread in the near future with my experiences.

Please allow me to expand on some of the electronic stuff.

Sorry MedEvil but you said:

Well luckily we do not really need to know or care.

We simply connect the wp pin via the switch to the positive power terminal of the chip. That has always the exact right voltage.

So yes, using the "positive power terminal of the chip" or Vss is advised. (Voltage supply source)

We do need some care here though.

If you supply an input pin on an IC device a higher voltage than Vss,

"You WILL destroy that input and perhaps the device."

Also, It is not a good idea to connect "any" pin of an IC directly to Vss or Ground,

unless it is, Vss or the Ground input pins, "Usually one of the corner pins of the IC chip, But not always, You "must" check the Data Sheet."

The idea is, that you don't want to subject a sensitive input pin on the IC

to all the nasty, dirty things going on at the power supply level.

so, you add a small amount of resistance in-series, to pull the pin low, or hi as needed.

A 1000 ohm resistor is usually sufficient. "Check Your Data Sheet"

Below is a simple schematic of how to acheive that.

You Simply solder a 1Kohm resistor to the common terminal of the spst (Single Pole Single Throw) switch.

then the Normally open contact goes to ground, and the Normally closed contact goes to Vss

Pins on the switch are usually marked as such, C= Common NC= Normally closed NO= Normally open

1 Kohm Resistor

.___/\/\/\___ Common --> wp pin

/

Vss <--./ .--> Ground

NC NO

To reiterate as MedEvil noted, "PLEASE use good judgement.",

and further, you may destroy your hardware or PCB traces with a soldering iron if not careful.

"Some helpful hints will follow, from a professional in the industry"

I just recently purchased a Tenma rework station from MCM for <= $60 US.

I have yet to use the station?, but on first inspection it seems like a very solid

device concerning the hot-air side, but it also comes with a very fine tip

on the soldering-station side which I hope to use very soon.

I like to think it will occupy a dedicated spot on my bench very soon.

For those of you just getting into servicing SMDevices,

Please allow me to suggest: http://www.chipquik.com/store/

In a nutshell, it is a solder that melts at a lower temp, and then also stays molten longer.

allowing for easier removal and desoldering of smd devices.

Regards

RoyM