Strobe Problem

348

Member
Feb 16, 2013
1,014
Idaho
I recently acquired a pair of North American Signal Co. model DFS900-A strobe beacons. They are self contained and designed to double flash. One does as it it should but the other seems to have a problem. When I give it power it takes about 30 seconds before it starts flashing. It will only single flash and its flash rate is about once every 5 seconds. It takes about 5 minutes to reach that flash rate. Even then the flash rate is inconsistent. I took it apart and it’s pretty clean with no obvious clues to where the problem lies. I’m curious if it’s fixable at a reasonable cost? Is there anyone on this website who repairs this type of light? Thanks in advance for any help.
 

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Reactions: kitn1mcc
Jun 18, 2013
3,709
PA
I'd start by recapping the light. Not that hard to do, you can source the caps from the information on the old caps your replacing.

I forgot to mention, you can test the caps with a multi meter to be 100% but you will still need to remove them from the board. Remember to make a note of polarity before removal, some PCBs will have markings showing + or -, the capacitor will as well.

From what is sounds like, you might have 1 bad one, while the others are good. I would replace all 3 of them.
 
Last edited:

irishff

Member
May 24, 2010
522
SW Missouri
This is one of two problems commonly found with strobes, especially older ones that have not been used in a while.

1. The strobe tube has low gas. Over time the glass can become brittle, sometimes not even be able to be seen by the naked eye, and the gas inside the bulb leaks out. IF some gas remains as the bulb heats up, the gas that is left will expand and allow for intermittent flashed to occur. Since there is not enough gas for normal operation, the heat quickly dissipates and the whole process has to start over.

2. Bad capacitor in the power supply. Like all electronic parts, capacitors can wear out over time. The capacitor is responsible for sending a big jolt of current to the bulb at a high voltage and making the gas fire. The capacitor receives electricity, holds onto it until a certain point, and then releases it all at one time to the bulb. Think of halogen bulbs getting electricity through a garden hose. Nice constant flow. A capacitor is like filling up a bucket with a garden hose and then when it reaches the top, dumping it over in one quick action.

So you either need to replace the bulb or the power supply. If the bulb simply unplugs, put it in the other light and see what happens. If you still have the problem in that housing, then it's the power supply, if the problem switches housings, then it's the bulb. I cannot tell but you may have to unsolder the bulb to change it, if that the case, take your time and be very patient.
 

348

Member
Feb 16, 2013
1,014
Idaho
Thanks everyone for their expertise. After some testing, it looks like the problem was with the bulb. I tried the bad bulb in both beacons and it acted up in both lights. I tried the good bulb in both beacons and it flashed as it should on both lights. Based on that, it appears the problem was with the bulb. I ordered a new one from North American Signal and should be back in business. Thanks again.
 

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