Ugh, that IS frustrating! LED C6 lights can be tricky. Since you've already ruled out the fuse, here's a breakdown of what's likely going on and how to tackle it

Understanding the Problem
Series Circuit Issues

C6 LED lights (especially older or cheaper ones) are often wired in series. This means that if one bulb fails (or its connection is broken), the entire string goes out past that point. That's why finding the bad one is crucial.

Voltage Drop

Sometimes, even if a bulb seems fine, it might be experiencing a high voltage drop. This prevents enough current from flowing through the string.

Shunt Resistors (Bypass Diodes)

Some (but not all) LED strings have shunt resistors built into each bulb socket or in the wiring. These are supposed to bypass a failed LED, allowing the rest of the string to light. However, they aren't always reliable, especially if multiple bulbs are out.

Troubleshooting Steps (Ordered by Ease of Implementation)1. The "Look Very Carefully" Method



Examine Each Bulb (Closely)

Look for: Cracked or broken bulbs. Dark spots inside the bulb (burnt out). Bulbs that are noticeably dimmer than the others (this could indicate a weakening LED). Gently wiggle each bulb in its socket to see if that restores the connection. Sometimes, just a loose contact is the issue.2.

The "Bulb Swap" Method (Best if You Have Replacement Bulbs) Get Replacement Bulbs

If you have spare C6 LED bulbs, this is the most reliable approach. If you don't, you can often buy small packs of replacement C6 LEDs online or at hardware stores.

Start at the Beginning (Closest to the Plug)

Remove the first few bulbs, and replace them with known working bulbs. Test after each replacement.

Continue Down the Line

Keep replacing bulbs until the string lights up. When it does, you've likely found the problematic bulb(s).

Important

Mark or set aside the bulbs you're removing so you know which ones you suspect are bad.3.

The "Voltage Tester" Method (Requires a Multimeter and Some Electrical Knowledge)



Safety First! Unplug the string before doing anything that involves touching the wires or sockets. Set Up Your Multimeter

Set your multimeter to measure DC voltage (usually around 20V or similar).

Test Across Sockets

Plug in the string. Carefully probe the metal contacts inside the bulb sockets, starting at the beginning of the string. You should see a voltage reading at each socket. The voltage will likely decrease as you move down the string. A socket with significantly lower voltage (or no voltage) compared to the others is a strong indicator that the bulb before that socket is the problem.4.

The "Jumper Wire" Method (Advanced and Potentially Risky - Use with Extreme Caution)



Unplug the String! Prepare a Jumper Wire

Use a small length of insulated wire (18-22 gauge is fine) with the insulation stripped off at both ends.

Bypass Bulbs

One by one, unplug a bulb and carefully touch one end of the jumper wire to one contact in the socket and the other end of the jumper wire to the other contact in the socket. This bypasses that bulb.

Plug In and Test

Briefly plug in the string. If it lights up, the bulb you bypassed is the problem. Unplug the string immediately after testing.

Caution

Only do this briefly. Bypassing too many bulbs can overload the remaining LEDs and damage them or the wiring.

Things to Consider



Inspect the Plug and Wiring

Even though you said the power goes through, double-check the plug for any loose connections, bent prongs, or damage to the cord.

Check for Cut or Damaged Wires

Look closely at the entire length of the string for any nicks, cuts, or kinks in the wiring. Especially check any connections.

LEDs Can Degrade

Unlike old incandescent bulbs, LEDs don't usually burn out in a sudden, obvious way. They can gradually lose brightness or change color over time, which can contribute to the problem.

Cheap vs. Quality

The price of LED lights often reflects their quality. Cheaper lights are more likely to have failures.

Storage

How were the lights stored? Were they exposed to moisture or extreme temperatures?

When to Give Up

If you've spent a significant amount of time troubleshooting and still can't find the problem, it might be time to cut your losses and buy a new set.

Important Safety Note



Work in a Dry Area

Never work on electrical devices in a wet environment.

Unplug First

Always unplug the lights before inspecting or replacing bulbs.

If You're Unsure, Get Help: If you're not comfortable working with electricity, consult a qualified electrician.Good luck! Let me know if you have any other questions. Flag for review