I have an AT89C4051 micro (powered with 5VDC) in which the reset pin is pulled down via a 100K resistor (formerly 39K) and pulled up via a 4.7uF tantalum capacitor. For simplicity, let's say a normally-open button is added in parallel with the capacitor even though one isn't there.
I hooked the positive lead of a voltmeter to the reset pin and grounded the negative lead of the voltmeter.
When I hold down the button, the results that were expected appeared (around 4.9VDC), however, when I let go of it, the voltage stays at about 2.6V. I was expecting the meter to slowly count down to 0V but it doesn't unless I remove a voltmeter lead from the circuit.
The only thing I could think of is that the insides of the capacitor are somehow broken, but I can't tell from the outside since nothing blew up on the board. I did measure the resistance across the capacitor and the meter stayed at -1 which suggested to me that no short circuit (yet) exists in the capacitor.
What can I do to correct this issue?