the clock on my grind and brew resets to 12:00 every time i unplug it, even for a second.

Diagnosis

The Cuisinart Grind & Brew DGB-900BC utilizes a volatile memory system for its internal clock and programmable timer. To maintain these settings during a power outage or when the unit is unplugged, the machine relies on a small lithium coin cell battery (typically a CR2032) located on the primary logic board. When this battery reaches the end of its service life—usually after 3 to 5 years—the circuit can no longer sustain the memory chip's state without an active 120V AC power source. The symptom of the clock flashing "12:00" immediately upon reconnection is the classic indicator of a "cold" memory chip. Because the battery is not providing the necessary 3V trickle charge, the microprocessor resets to its factory default state every time the power cycle is interrupted. You can confirm this by unplugging the machine for just ten seconds; if the clock resets, the battery is completely depleted or the solder joint connecting the battery holder to the board has cracked due to thermal expansion from the heating element.

How to Fix It

To replace the CMOS battery and restore the clock's memory, you will need a Phillips #2 screwdriver, a precision flat-head screwdriver, and a replacement CR2032 3V lithium battery.

1. Unplug the machine from the wall outlet and allow it to cool completely to avoid burns from the heating plate.
2. Flip the machine upside down on a soft towel. Locate the rubberized non-slip feet on the bottom of the chassis. Use a flat-head screwdriver to gently pry up the rubber feet to reveal the hidden screws beneath them.
3. Remove the four primary chassis screws. Carefully lift the plastic bottom housing away from the main body. Be mindful of the wires connecting the power switch to the main board; do not yank the housing away.
4. Locate the main control PCB (Printed Circuit Board). Look for a circular, silver metal coin cell holder. In most DGB-900BC revisions, this is a solder-in clip holder.
5. Use a small flat-head screwdriver or a pair of tweezers to gently pry the dead CR2032 battery out of the clips. Do not apply excessive force, as bending the metal tabs too far can prevent the new battery from making a secure connection.
6. Insert the new CR2032 battery with the positive (+) side facing upward. Ensure it clicks firmly into place.
7. Reassemble the housing, tighten the screws, and replace the rubber feet. Plug the unit back in and set the clock. Unplug it for 30 seconds to verify the time is now retained.

If That Didn't Work

• Check for Cold Solder Joints: If a new battery doesn't fix the issue, inspect the two solder points where the battery holder meets the PCB. Thermal stress from the coffee boiler can cause "ring cracks" in the solder. Use a soldering iron to reflow the joints with a small amount of fresh lead-free solder to ensure a solid electrical path.
• Inspect the Capacitor: Look for the electrolytic capacitors near the power input section of the board. If the top of a capacitor is bulging or leaking a brownish fluid, it can cause voltage instability that prevents the battery from maintaining the clock. These must be desoldered and replaced with capacitors of the same microfarad (µF) and voltage rating.
• Test the Battery Voltage: Use a digital multimeter to test the new battery before installation. Some "new" batteries from bulk packs can arrive dead. Set your meter to DC Voltage and ensure the battery reads at least 3.0V to 3.3V.
• Verify the Power Cord Integrity: If the clock resets even while plugged in during slight flickers, check the power cord for frays or loose connections at the base of the machine, as intermittent power delivery can trigger a reset cycle.

Heads Up

• Avoid using generic, off-brand batteries; high-quality name-brand lithium cells last significantly longer in the high-heat environment of a coffee maker.
• Never touch the PCB with your bare fingers if you can avoid it; use an anti-static wrist strap or touch a grounded metal object to prevent ESD (Electrostatic Discharge) from frying the microprocessor.
• Be extremely careful not to pinch the internal wiring when snapping the bottom plastic housing back into place, as this can lead to a short circuit once powered on.
• Clean the area around the battery holder with a cotton swab and 90% isopropyl alcohol while the machine is open to remove any leaked battery acid or coffee residue.