certain tools read better “in-circuit” then others. It’s knowing which ones can perform the task without corruption and setting up to read them properly. Removing them
Is not always necessary.
If you read at 5v you MUST short out the crystal when in-circuit. It’s always good habit to short out the crystal regardless. 3.3v is enough to only read eeprom and now power up MCU.
this is why the data sheet is always important but when the tool defaults to 5v … you have to be aware of this. The thing is some tools will set the voltage accordingly and make this a mute point.
this is a crystal (they come in different shapes and sizes) take a jumper lead and place it between the two leads so that the power doesn’t power up the MCU, on this particular example the legs could extend through the board and you would have to flip the board over and jump those two legs
Thanks to Kevin Suttorp