How do I fix flickering/dim lamps (light bulbs)

Games affected: all

The lamp circuits are usually pretty simple, and that makes it easy to fix problems with lamps that flicker, are dimmer than they should be, or don't work at all (let's assume the lamp itself is good and is the right number - except #55's and #44's can/should be replaced with #47's (some people just don't like the dimmer #47''s up to you - it's your backglass and playfield light sheilds), #1458's are harder to come by, so #1464's for those can be used instead).

The first step is to isolate the problem. It will almost always be an issue with the lamp socket, and to verify all you need to do is wiggle the lamp in the socket to see if it comes on/brightens. If that doesn't help, then it's most likely a problem on a stepper unit or a trip bank switch.

The lamp sockets

There are two main styles of lamp sockets. The first is a standard bayonet socket that is readily available and cheap if you just want to replace it. There are different shapes, though, so make sure you get the right one.

Lamp socket style #1

This lamp socket has three problem areas:
  1. connection between the socket and the mounting bracket. If the socket can spin around on the bracket, replace it or you can solder the socket to the bracket. If the lamp just wobbles in the socket, you can use some pliers to slightly deform the socket so the lamp fits more snugly.
  2. solder tab connection to lamp tip. If this is loose, it's easiest to replace the socket, but you can try soldering the pieces together. Just don't get solder into the spring-loaded plunger. The tip of the plunger and/or the tip of the lamp may also be dirty.
  3. poor solder connection to mounting bracket. Reflow the solder.

side and botton view
Lamp socket style #2

This lamp socket is pounded into the wood, and usually there are only two problems:
  1. center tab is not exerting enough pressure on the lamp tip. bend the tab up so it applies more pressure. With power to the socket off (no ball in hole or spotted), remove the lamp and from the front insert a small flat-bladed screwdriver behind the tab and pry/bend the tab towards you. You don't have to be cautious'll pretty much pry the tab way past where it needs to be and it will spring back when released. The goal is to have the lamp not wiggle loosely in the socket when inserted. Rarely you'll break off the tab. If that happens, it wasn't applying much pressure anyway. I've only seen this on one machine...I assume some environmental factor was corroding the sockets as multiple broke.
  2. lamp tip is mangled. This type of socket digs a pretty big pit in the tip of the lamp, which is a pretty soft metal. You can reshape the tip to remove the divot, or just toss the lamp.