Possible causes for bulbs out on set of 120 lights

[housemaid01]

Hi. Please can anyone advise a possible cause for bulbs out on a set of 120 outdoor chasing bubble lights. They are around 12 years old. To date I have checked that all bulbs are working and replaced any faulty ones. At one end of the string there are bulbs out at every other bulb, then half way this changes to every 3rd or 4th bulb out. The wiring is intact and in very good condition.

 

[Sharpend]

Is there any sign of corrosion? Start with the lamp nearest to plug that is out, remove lamp and look for any rust/corrosion. Without proper test equipment it may be difficult to establish cause.
Some might suggest that at 12yrs old it might be more economical to replace them?

 

[Richard-the-Ninth]

If you have proven that ALL the lamps work, it can only be a wiring issue, be that a broken wire or as Sharpend suggests corrosion in one of the lamp holders. If your time is free, then yes, take each lamp out, test it, have a close inspection of the lamp holder. Picture of the string would be nice But also as Sharpend suggests @12 years old, I would consider changing them to something better, have you considered "LED Pixels" (Colour changing, sequencing etc)

 

[Geoff1946]

Are they directly mains powered, or low voltage?

 

[Bruspark]

Far-east Outdoor lights mean corrosion and poor connections, everywhere.
They have lasted 10 times longer than the manufacturer expected so cut your losses and replace them

 

[housemaid01]

Any thanks for your replies. As suggested, I will recycle and replace. On further inspection it looks like at least 2 of the bulb holder have broken conductors where the bulbs connect.

 

[housemaid01]

Are they directly mains powered, or low voltage?

Mains powdered

 

[Geoff1946]

Mains powdered

Overtaken by events now, if you've found the fault and binned them, but I was going to suggest that a volt-stick (non contact tester), is ideal for locating the break in series light chains.