Question 1

my drill sometimes just won't start, i pull the trigger and nothing happens, but if i whack it on the table it starts working

Accepted Answer

DIAGNOSIS This behavior is a classic symptom of a "mechanical-electrical disconnect," typically caused by a fatigued solder joint or a loose terminal connection within the DCD771C2's trigger assembly. Because the drill functions after a physical impact (whacking it on the table), you are dealing with an intermittent open circuit. The vibration from the impact momentarily forces two separated metal surfaces back into contact, completing the electrical path from the 20V battery to the motor. In the DCD771C2 model, the most common failure point is the solder joint where the heavy-gauge power wires connect to the trigger switch PCB. Due to the high vibration of drilling and the torque of the motor, these joints can develop "cold solder" cracks or hairline fractures. Alternatively, the carbon brushes in the motor may have become worn or stuck, preventing them from making consistent contact with the commutator, though the "whack to start" symptom more frequently points to the trigger housing or the battery terminal spring tension. FIX To resolve this, you must perform a continuity check and resolder the internal connections. You will need a T15 Torx driver and a 30W-60W soldering iron. Remove the 20V Max battery pack and place the drill on a stable work surface. Using the T15 Torx driver, remove all housing screws. Note that some screws are recessed in deep holes; ensure you apply firm pressure to avoid stripping the heads. Carefully pry the clamshell halves apart. Be cautious not to snap the plastic alignment tabs. Locate the trigger switch assembly. Inspect the two primary power wires (typically red and black) where they are soldered to the switch terminals. Look for a "ring" crack in the solder—this is a clear sign of a failed joint. Using your soldering iron and a small amount of lead-free solder, reflow the joints. Heat the wire and the pad simultaneously for 2-3 seconds until the solder flows smoothly and forms a concave fillet. Inspect the battery terminal contacts at the base of the handle. If the spring-loaded pins appear compressed or oxidized, gently pull them outward by 1mm using needle-nose pliers to ensure a tighter grip on the battery terminals. Reassemble the housing, ensuring no wires are pinched between the plastic shells, and tighten the T15 screws firmly but not over-tight. IF THAT DIDN'T WORK Replace the Trigger Switch: If reflowing the solder doesn't work, the internal contact plates within the switch assembly may be pitted or worn. Replace the trigger assembly entirely (Part No. DCD771-S) to restore consistent current flow. Inspect Motor Brushes: If you see sparks inside the motor housing when it finally starts, the carbon brushes may be stuck in their holders. Gently tap the motor casing with a rubber mallet to reseat them, or replace the brush set if they are worn down to less than 3mm. Test Battery Terminals: Check for "arcing" marks (black carbon buildup) on the battery's gold-plated terminals. Clean these with a cotton swab dipped in 90% isopropyl alcohol to ensure there is no resistive layer blocking the current. Check the Forward/Reverse Slider: The sliding switch can sometimes get jammed halfway, preventing the trigger from engaging the circuit. Use a can of compressed air to blow out any drywall dust or sawdust from the slider mechanism. HEADS UP Avoid Over-Tightening: The plastic housing of the DCD771C2 is durable, but over-tightening the T15 screws can crack the casing, which will lead to the drill vibrating more and causing the same electrical failure to return. Dust Management: This drill is not fully sealed. If you use it for drywall or masonry, blow out the trigger area with compressed air every few projects to prevent conductive dust from bridging the switch contacts. Battery Storage: Never store your 20V Max batteries in freezing temperatures, as this can cause internal cell degradation that mimics a "dead" or intermittent connection at the terminals. Solder Caution: When soldering the trigger board, work quickly. Excessive heat applied to the PCB can lift the copper pads, which would permanently destroy the switch assembly.

Question 2

the chuck on my drill is seized shut, can't open it to change the bit no matter how hard i twist

Accepted Answer

DIAGNOSIS The DCD771C2 utilizes a keyless ratcheting chuck that relies on a series of internal threaded sleeves and a spring-loaded locking mechanism. When the chuck seizes, it is typically due to "galling" or oxidative bonding. This occurs when microscopic metal shavings from drilling into steel or aluminum migrate into the sleeve threads, or when moisture penetrates the housing, causing surface rust to fuse the internal drive nut to the outer sleeve. You can confirm a mechanical seizure if the outer sleeve rotates freely (clicking) but the jaws do not move, or if the sleeve is completely immobile. If the sleeve clicks but the jaws stay shut, the internal drive gear has likely stripped or disconnected. If the sleeve won't budge at all, the outer sleeve is physically bonded to the inner assembly through corrosion or debris buildup. This is common in environments with high humidity or when the tool is used for heavy-duty masonry work without frequent cleaning. FIX To break the seal on a seized DCD771C2 chuck without damaging the internal planetary gears, follow these precise steps: Position the drill on a stable workbench. Insert a high-quality 1/4" hex shank bit or a sturdy Allen wrench into the jaws. Ensure it is seated as deeply as possible. Apply a generous amount of penetrating oil (such as PB Blaster or Liquid Wrench) around the seam where the rotating sleeve meets the main body of the drill. Let it soak for at least 15 minutes. Using a pair of locking pliers (Vise-Grips), firmly grip the outer chuck sleeve. Do not squeeze so hard that you deform the metal, but ensure a non-slip grip. While holding the sleeve with the pliers, take a rubber mallet or a small hammer and give the back of the inserted bit a sharp, sudden tap in the counter-clockwise direction. The goal is to send a shockwave through the spindle to break the oxidative bond. Slowly rotate the sleeve counter-clockwise. If you feel resistance, do not force it with maximum torque immediately; instead, oscillate the sleeve back and forth (clockwise and counter-clockwise) in small increments to "walk" the debris out of the threads. Once the jaws begin to move, fully open the chuck and apply a dry silicone lubricant to the internal threads to prevent future seizing. IF THAT DIDN'T WORK Heat Expansion Method: Use a heat gun or a high-wattage soldering iron to carefully heat the outer sleeve of the chuck for 60 seconds. The thermal expansion of the outer sleeve relative to the inner spindle often breaks the rust bond. Immediately attempt to rotate the sleeve while the metal is still warm. Impact Driver Technique: If you have access to another impact driver, place a socket adapter and a fitting socket over the chuck sleeve. Use the rapid-fire percussion of the impact driver in the reverse direction to shake the internal mechanism loose. Chemical Bath: Submerge the entire front end of the drill (chuck area only) in a shallow bath of acetone or a dedicated rust remover for 2-4 hours. This penetrates deeper than spray lubricants. Ensure the battery is removed and the vents are kept clear of the liquid. Full Chuck Replacement: If the sleeve continues to spin without moving the jaws, the internal drive nut is stripped. You will need to remove the three internal screws holding the chuck to the spindle and replace the chuck assembly entirely. HEADS UP Avoid using WD-40 Multi-Use Product for this fix; it is a solvent, not a true penetrating oil. Use a dedicated penetrant like PB Blaster or Kroil for seized threads. Never use a pipe wrench on the chuck sleeve, as this will crush the thin-walled sleeve and permanently jam the mechanism. After every 10-15 uses in dusty environments, blow out the chuck with compressed air to remove metal filings before they settle into the threads. Always ensure the drill is in "Forward" or "Reverse" gear rather than the center trigger lock when attempting to manually break a seized chuck to avoid damaging the trigger assembly.

Question 3

dewalt drill smells like burning and gets really hot near the motor just holding the trigger for a few seconds

Accepted Answer

DIAGNOSIS The burning smell and rapid heat buildup in the DCD771C2 are classic symptoms of a catastrophic failure in the motor's electrical or mechanical integrity. Because this model utilizes a brushed DC motor, the most common culprit is "arcing" at the commutator. When the carbon brushes wear down unevenly or the commutator develops "pitting" (small burnt craters), the electrical current jumps across gaps, creating intense heat and a distinct ozone/burnt plastic smell. If the heat is felt almost instantly upon pulling the trigger without a load, you likely have a partial short in the armature windings, meaning the insulation on the copper wire has melted, allowing current to bypass the coils and generate raw heat. Alternatively, the issue may be mechanical friction caused by a seized or contaminated motor bearing. If the front bearing has failed or ingested metallic debris from the gear housing, the motor must fight immense physical resistance to spin. This forces the motor to draw maximum amperage from the 20V battery, which rapidly overheats the windings and the trigger switch assembly. You can confirm this by removing the battery and attempting to spin the chuck by hand; if there is any "grittiness" or significant resistance compared to a healthy unit, the bearing or the planetary gears are the primary failure point. FIX To resolve this, you must replace the motor assembly and inspect the trigger switch for heat damage. Safety First: Remove the 20V Max battery pack immediately. Do not attempt to disassemble the tool with the power source connected. Case Disassembly: Using a T15 Torx driver, remove the screws from the clamshell housing. Be careful not to lose the small screws located near the grip and the base of the handle. Gently pry the two halves of the casing apart using a plastic trim tool to avoid marring the plastic. Component Extraction: Locate the motor assembly at the rear of the tool. Carefully disconnect the two heavy-gauge wires connecting the motor to the trigger switch. Note the polarity (color coding) to ensure the drill does not spin in reverse upon reassembly. Motor Replacement: Unscrew the motor mounting bolts. Slide the old motor out of the housing. Install a replacement DCD771-compatible brushed motor. Ensure the motor shaft is seated fully and flush against the planetary gear assembly. Cleaning and Lubrication: Before closing the case, use compressed air to blow out any carbon dust or metallic shavings from the gear housing. Apply a small amount of high-temp lithium grease to the planetary gears if the grease appears dry or blackened. Reassembly: Reconnect the motor wires to the trigger switch, ensuring the connections are tight and insulated. Snap the housing back together and tighten the T15 screws. Testing: Insert the battery and pull the trigger in short bursts. Check for smooth acceleration and a lack of burning odors. IF THAT DIDN'T WORK Replace the Trigger Switch: If the motor is new but the heat persists or the smell remains, the trigger switch (potentiometer) may have an internal short. A failing switch can send erratic voltage to the motor or overheat itself, melting the surrounding plastic housing. Replace the trigger assembly entirely. Inspect the Planetary Gearbox: If the motor is straining, a chipped tooth in the planetary gear set can cause a "binding" effect. This creates massive mechanical drag that manifests as heat in the motor. If you see metal flakes in the grease, the gearbox assembly must be replaced. Check for Battery Internal Short: A faulty 20V battery cell can occasionally cause a voltage spike or instability. Test the drill with a different, fully charged 20V Max battery. If the problem disappears, the original battery pack is the source of the electrical instability. Verify Chuck Alignment: If the chuck is jammed or the internal bearings of the spindle have collapsed, it will put an immense load on the motor. Try removing the chuck (if applicable) or spinning the spindle to ensure it moves freely without the motor engaged. HEADS UP Carbon Dust Danger: Always blow out the motor area with compressed air during service. Accumulated carbon dust from the brushes can become conductive, leading to "tracking" shorts that can fry a brand new motor. Avoid "Stalling": To prevent this from happening again, avoid "stalling" the drill (holding the trigger while the bit is completely stopped in a hard material). This creates a "locked rotor" condition that generates maximum heat in seconds. Cool-Down Periods: If you are drilling large diameter holes in hardwood, allow the tool to idle (spin without a load) for 10 seconds between holes to use the internal fan to cool the armature. Grease Quality: Never use WD-40 or thin oils inside the gear housing; use only high-pressure lithium grease. Thin oils will sling off the gears and may migrate into the motor windings, causing a fire hazard.

Question 4

the forward/reverse switch on my dcd771 is super stiff and sometimes gets stuck in the middle

Accepted Answer

DIAGNOSIS The stiffness or "middle-sticking" of the forward/reverse slider on the DeWalt DCD771C2 is almost always caused by an accumulation of particulate matter—specifically fine sawdust, drywall compound, or metallic filings—that has migrated past the external housing of the switch. The DCD771 uses a sliding mechanical actuator that engages a set of internal microswitches. When grit enters the narrow gap between the slider and the tool casing, it creates friction that resists the spring-loaded return of the switch. If the switch sticks in the center (neutral), it means the actuator is physically wedged or the internal spring tension is being overcome by debris. This is a critical failure point because if the switch remains in the center position, the trigger will not engage the motor, leading the user to believe the battery is dead or the tool has suffered a total electrical failure. You can confirm this by attempting to move the switch while the tool is off; if you feel a "gritty" sensation or a hard stop before the switch fully clicks into the forward or reverse position, the mechanism is contaminated. FIX To restore the smooth operation of the DCD771 slider without fully dismantling the gear housing, follow these precision cleaning steps: Remove the 20V Max battery pack immediately to ensure no accidental trigger pulls occur during the cleaning process. Use a high-pressure can of compressed air with the narrow straw attachment. Insert the straw into the gap between the slider and the tool body. Blast air from the left side toward the right, and then from the right toward the left, focusing specifically on the base of the slider where debris tends to settle. Apply a non-conductive, fast-evaporating electrical contact cleaner (such as CRC QD Contact Cleaner). Do not use WD-40 or silicone lubricants, as these attract more dust and will create a "sludge" that worsens the sticking over time. Spray the cleaner directly into the crevices around the switch. While the solvent is still wet, rapidly toggle the switch back and forth between forward and reverse 20 to 30 times. This action flushes out the loosened grit and cleans the contact points of the internal microswitches. Use a clean, dry microfiber cloth to wipe away any residue that has been pushed out of the switch housing. Allow the tool to air-dry for at least 10 minutes to ensure the solvent has completely evaporated before reinserting the battery and testing the trigger. IF THAT DIDN'T WORK Deep Internal Cleaning: If the slider remains stiff, the debris has likely migrated inside the plastic shell. You will need to remove the outer casing screws (typically T15 Torx) to access the switch assembly. Once the shell is open, use a soft-bristled brush to manually remove packed dust from the slider rail before reapplying contact cleaner. Switch Replacement: If the switch continues to stick in the center despite cleaning, the internal return spring may have snapped or the plastic guide rail has worn down. In this case, the entire forward/reverse switch assembly needs to be replaced. Search for the specific DCD771 replacement switch part to ensure compatibility with the 20V Max circuitry. Checking for Housing Warpage: Inspect the plastic casing around the switch for any cracks or deformations, especially if the tool has been dropped. A warped housing can pinch the slider, making it feel stiff regardless of cleanliness. If the plastic is pinched, you can carefully shave a fraction of a millimeter of plastic from the inner guide using a small needle file. HEADS UP Avoid using oil-based lubricants on the switch; these act as magnets for construction dust and will lead to a permanent jam. Always blow out your tools with compressed air after working in high-dust environments like drywall sanding or masonry drilling to prevent this issue. Never force the switch into position if it feels stuck; doing so can snap the internal plastic tabs or crush the microswitches, requiring a full assembly replacement. Ensure the battery is removed before applying any liquid cleaners to avoid shorting the control board.

Question 5

my drill works on speed 2 but makes a horrible grinding noise and barely moves on speed 1

Accepted Answer

DIAGNOSIS The grinding noise and lack of torque on Speed 1 indicate a mechanical failure within the planetary gear system of the DCD771C2. Specifically, the low-speed gear train—which consists of a series of reduction gears designed to multiply torque—has likely suffered a "stripped" tooth or a fractured gear face. When you shift to Speed 2, the drill bypasses the primary reduction stage, which is why it continues to function, albeit with less power. The root cause is typically caused by "over-torquing" the tool or attempting to force a fastener that exceeded the drill's rated capacity, causing the hardened steel teeth of the Speed 1 pinion to shear off. You can confirm this by shifting to Speed 1 and pulling the trigger lightly; if you hear a high-pitched metallic rattling or "chattering" without the chuck rotating, the internal gear teeth are no longer meshing. If the chuck rotates but slips under the slightest pressure, the gear teeth are stripped. FIX Because the gear assembly in the DCD771C2 is integrated, you cannot replace a single gear; you must replace the entire transmission/gearbox assembly. Power Down: Remove the 20V Max battery pack immediately to prevent accidental trigger activation. Housing Disassembly: Using a T15 Torx driver, remove the 6-8 screws securing the plastic clamshell housing. Be careful not to strip the plastic bosses. Internal Extraction: Gently pry the two halves of the housing apart. Lift the motor assembly out of the chassis, ensuring you do not pinch the wires connecting the motor to the trigger switch. Gearbox Removal: Slide the speed selector ring forward to the "neutral" position between 1 and 2. Unscrew the mounting bolts holding the gearbox to the motor frame. Installation: Slide the new transmission assembly (Part #D25312-000 or equivalent gear kit) onto the motor armature. Ensure the splines are perfectly aligned before tightening the mounting bolts. Reassembly: Seat the motor and trigger assembly back into the housing. Align the housing seams and tighten the T15 screws in a star pattern to ensure even pressure across the casing. IF THAT DIDN'T WORK Inspect the Speed Selector Ring: If the new gears don't solve it, the sliding selector ring may be worn or cracked, preventing it from fully seating into the Speed 1 position. If the ring feels "loose" or doesn't click firmly into place, replace the selector sleeve. Check for Motor Armature Debris: Inspect the motor shaft for any metal shavings or "glitter" left over from the failed gears. If debris has entered the motor brushes or the commutator, it can cause erratic speed behavior. Clean with compressed air. Verify Chuck Alignment: In some rare cases, the grinding is actually coming from the chuck bearings rather than the gears. Try removing the chuck; if the gearbox rotates smoothly without the chuck attached, the issue is a failed chuck bearing. Test the Trigger Switch: If the drill "stutters" on Speed 1 but not Speed 2, the variable speed trigger may have a dead spot in the low-voltage range. Test with a multimeter to ensure consistent voltage delivery to the motor. HEADS UP Avoid "Force-Shifting": Never move the speed selector ring while the trigger is being pulled. Shifting under load is the primary cause of stripped gear teeth in the DCD771 series. Grease Maintenance: When installing a new gearbox, ensure it is packed with high-temperature lithium grease. If the unit arrives dry, apply a small amount of molybdenum disulfide grease to the gear faces. Torque Management: If you frequently find yourself needing more torque than Speed 1 provides, switch to a dedicated 20V Max Impact Driver to avoid burning out the planetary gears of your drill.

Question 6

the battery meter on my dewalt 20v drill only shows one bar even after a full charge, is the drill broken

Accepted Answer

DIAGNOSIS The issue is not with the DCD771C2 drill motor or its internal circuitry, but rather a failure within the DC 20V Max battery pack's chemistry or the Battery Management System (BMS). The battery meter on the drill is a voltage-based indicator; it measures the potential difference across the terminals to estimate remaining capacity. When a single lithium-ion cell within the pack develops high internal resistance or drops below a critical voltage threshold, the BMS detects a voltage sag. This happens because these packs consist of multiple cells wired in series. If one cell is "unbalanced" or degraded, it creates a bottleneck. Even if the charger indicates a "green" full charge, the voltage drops precipitously the moment the circuit is closed. This results in the drill reporting only one bar of power because the overall pack voltage has plummeted under the initial load of the trigger pull. You can confirm this by attempting to drive a large 2.5-inch lag screw; if the drill cuts out almost immediately despite the "full" charge, the pack has lost its capacity to hold a load. FIX To resolve this and confirm the hardware status, follow these specific validation and replacement steps: Remove the suspect battery pack from the DCD771C2 base. Inspect the gold-plated contact terminals on both the battery and the drill. Use a cotton swab dipped in 90% isopropyl alcohol to clean any carbon buildup or debris that may be causing a high-resistance connection. Insert a known-good 20V Max battery (preferably a high-capacity 4.0Ah or 5.0Ah pack) into the drill. Press the fuel gauge button on the battery itself before inserting it into the tool to check the onboard reading. Insert the known-good battery and pull the trigger. If the drill meter now shows full bars and the tool operates at full RPM, the DCD771C2 is functioning perfectly and the original battery is chemically depleted. Discard the failing battery at a certified lithium-ion recycling center and replace it with a genuine DeWalt DCB182 or DCB205 pack. IF THAT DIDN'T WORK Check the Charger Output: If multiple batteries are showing the same "one bar" symptom, your DCB115 charger may be failing. Use a multimeter to check the output voltage of the charger pins; if it isn't providing a steady 20V-21V during the charge cycle, it is "ghost charging" the batteries—showing a full light without actually saturating the cells. Inspect for Trigger Spring Fatigue: If the battery is definitely good but the meter flickers or stays low, the variable speed trigger switch may be worn. If the trigger doesn't make a clean contact, it can cause an erratic voltage drop across the internal switch, tricking the meter into reading a low state. Test for Terminal Compression: Check the plastic battery rails on the drill. If the rails are cracked or worn, the battery may not be seating firmly against the pins. Use a small piece of electrical tape on the battery's top rail to create a tighter fit and see if the meter reading stabilizes. Internal Wiring Check: If you are comfortable opening the chassis, check the wiring harness leading from the battery terminals to the trigger assembly. A pinched or frayed wire can cause a voltage drop that manifests as a low battery reading on the LED display. HEADS UP Never attempt to "jump start" or manually charge individual cells inside a DeWalt 20V pack; the BMS will permanently lock the pack for safety if it detects an improper voltage spike. Avoid storing your batteries in temperatures below 32°F (0°C) or above 104°F (40°C), as extreme temperatures accelerate cell degradation and lead to the "one bar" failure. To prolong battery life, avoid running the pack down to 0%. Stop using the tool when it begins to slow down; deep-discharging lithium cells significantly shortens their total cycle life. Always ensure the battery is fully clicked into place. A loose connection can cause intermittent power delivery and misleading fuel gauge readings.

Question 7

dewalt dcd771 chuck wobbles and bits won't stay tight, it's not the bit itself

Accepted Answer

DIAGNOSIS The wobbling and failure to grip bits on the DeWalt DCD771C2 are typically caused by a failure in the internal jaw mechanism or a stripped spindle interface. Because this is a keyless ratcheting chuck, the internal springs and the lead screw that drives the three jaws can become fouled with metal shavings or sawdust, preventing the jaws from closing fully. If you notice the bit "walking" or slipping during high-torque applications, the jaw serrations have likely worn down, or the chuck has shifted slightly on the spindle. Another common root cause is "run-out," which occurs when the spindle—the metal shaft the chuck attaches to—becomes bent due to excessive side-loading or a hard drop on a concrete surface. To confirm if the issue is the chuck or the spindle, open the jaws fully and rotate the chuck by hand. If the outer sleeve remains steady but the internal jaws oscillate in a circle, the jaws are worn. If the entire assembly shifts off-center as it rotates, the spindle is bent, and replacing the chuck alone will not solve the wobble. FIX Replacing the chuck is the most effective solution for restoring precision. You will need a replacement 1/2-inch keyless chuck compatible with the DCD771 series and a set of hex keys. Remove the battery pack from the DCD771C2 to ensure there is no accidental trigger pull during the process. Open the chuck jaws as wide as possible. Look deep inside the throat of the chuck for a small internal set screw. This screw locks the chuck to the spindle. Using a precision hex driver, loosen this set screw. Note that depending on the production batch, this may be a reverse-thread screw; if it doesn't move counter-clockwise, try turning it clockwise to break the tension. To remove the entire chuck assembly, you must apply clockwise torque to the chuck. Since you cannot use a wrench on the smooth sleeve, insert a large, sturdy drill bit (1/2" or 3/8") into the jaws and tighten them. Grip the bit with a pair of locking pliers (Vise-Grips) or a pipe wrench and rotate the entire chuck assembly counter-clockwise. The chuck will unscrew from the spindle. Clean the spindle threads with a wire brush and a small amount of degreaser to remove any accumulated debris or old thread-locker. Thread the new replacement chuck onto the spindle by hand to avoid cross-threading. Tighten it firmly using the same locking pliers method. Tighten the internal set screw securely to prevent the chuck from spinning independently of the spindle. Insert a test bit and check for concentricity by spinning the drill at low RPM and observing the bit's path. IF THAT DIDN'T WORK Check for Spindle Run-out: If the new chuck still wobbles, the spindle is bent. Use a dial indicator against the spindle shaft. If the deviation exceeds 0.005 inches, the entire gear housing/motor assembly must be replaced, as the spindle is not a standalone replaceable part on the DCD771. Inspect the Collet Springs: If the bits are tight but the chuck feels "mushy," the internal ratcheting mechanism is failing. Try spraying a high-pressure electronics cleaner or compressed air into the jaw tracks to clear out compacted debris that may be blocking full closure. Verify Bit Shank Quality: Ensure you are using high-quality hex-shank bits. Low-grade bits with undersized shanks (less than 1/4") will not engage the jaws properly, regardless of how tight the chuck is. Check Gearbox Alignment: If you hear a grinding noise accompanying the wobble, the internal planetary gears may be chipped. This usually happens after a severe impact and requires a full gearbox replacement. HEADS UP Avoid "over-tightening" the chuck with a wrench if you are using a keyless model; excessive force can distort the internal ratcheting rings. Never use the drill to "hammer" a bit into a hole, as this puts immense lateral pressure on the spindle and is the primary cause of the wobble. Periodically blow out the chuck jaws with compressed air to prevent sawdust from migrating into the lead screw mechanism. When installing a new chuck, apply a tiny drop of blue medium-strength thread-locker to the spindle threads to prevent the chuck from loosening during heavy vibration.

Question 8

my dewalt 20v drill just clicks when i pull the trigger, battery is charged and it feels like it's trying but nothing spins

Accepted Answer

DIAGNOSIS The clicking sound you hear when pulling the trigger on your DeWalt DCD771C2 is the sound of the motor's armature spinning and the trigger switch engaging, but the torque is not being transferred to the chuck. This indicates a mechanical failure within the planetary gear system. Specifically, the teeth on the sun gear or one of the planetary gears have stripped or sheared off, causing the gears to "slip" or jump rather than mesh and rotate. This typically happens when the tool is used under heavy load without the clutch being set correctly, or if the drill was forced in reverse while under high torque. You can confirm this by checking the gear selector switch on top of the tool. If the drill clicks in both Speed 1 (low) and Speed 2 (high), the failure is likely in the final drive stage of the transmission. If it only clicks in one speed, the issue is isolated to the specific gear set for that speed. Because the motor is "trying" (indicated by the humming or clicking), the electrical circuit, battery, and trigger assembly are functioning correctly; the break is entirely mechanical. FIX To resolve this, you must replace the transmission assembly. On the DCD771C2, the gears are housed in a modular assembly that can be swapped without replacing the entire tool. Remove the 20V Max battery pack and set it aside to ensure no accidental trigger pulls occur during disassembly. Using a T15 Torx driver, remove the long housing screws located on the side and top of the gear casing. Be careful not to lose the smaller screws that secure the clutch ring. Carefully pull the motor and trigger housing away from the front gear housing. You may need to gently tap the casing with a rubber mallet to break the seal of the plastic mating surfaces. Slide the motor armature out of the rear of the gear assembly. Note the orientation of the motor pinion gear. Remove the stripped transmission module. This is the internal gear cluster that connects the motor to the chuck spindle. Install a new replacement transmission assembly (ensure the part matches the DCD771 series specifications). Align the planetary gears carefully so they seat fully into the housing. Slide the motor armature back into the new transmission, ensuring the pinion gear meshes perfectly with the first stage of the planetary set. Reassemble the housing, tightening the T15 screws in a cross-pattern to ensure an even seal and prevent the casing from warping. IF THAT DIDN'T WORK Check the Chuck Spindle: If the gears are intact but the drill still clicks, the internal threads of the chuck may have stripped from the spindle. Try removing the chuck entirely and pulling the trigger; if the spindle rotates but the chuck doesn't, you need a replacement chuck rather than a gear assembly. Inspect the Gear Selector: The sliding speed switch on top may be stuck in a "halfway" position between Speed 1 and Speed 2. Use a can of compressed air to blow out any construction debris from the selector switch and toggle it firmly back and forth several times to ensure it is fully engaged in one position. Verify Motor Pinion Wear: Examine the small gear (pinion) on the end of the motor shaft. If the teeth on the motor itself are rounded off, a new transmission won't help because the motor cannot drive the gears. In this case, the entire motor assembly must be replaced. Check for Obstructions: Inspect the vents and the area around the motor for metal shavings or debris that may be jamming the planetary gears, preventing them from rotating despite the motor's effort. HEADS UP Grease the Gears: When installing a new transmission, apply a small amount of high-pressure lithium grease to the planetary gears. Running these dry will lead to rapid wear and another failure. Clutch Management: To prevent this from happening again, always adjust the torque clutch ring (the numbered dial) to the lowest setting necessary for your task. Forcing the drill through a material that exceeds the clutch limit puts immense stress on the planetary gears. Avoid "Shock" Loading: Avoid switching the drill from forward to reverse while the motor is still spinning at high RPMs, as this creates a mechanical shock that can shear gear teeth instantly. Battery Heat: If you are using the drill for heavy-duty boring, allow the motor to cool. Overheating can soften the plastic components within the gear housing, leading to misalignment.

DeWalt 20V Max Cordless Drill DCD771C2

Other Power Tools