How to test an automotive  HID lamp ballast? - Page 1
Forum section: electronics / beginners

author: dog80
author_rank: Regular Contributor
timestamp: September 13, 2013, 01:14:01 pm
content: How should I test a HID ballast? My multimeters are rated for 1000 Volts and apparently these ballasts put out 5000 or more volts.

author: ConKbot
author_rank: Super Contributor
timestamp: September 13, 2013, 01:26:08 pm
content: Hook it up to a known good lamp and get a decently beefy 12v battery(I.e. not a 12v carbon-zinc lantern battery). If it lights, pass. If it doesn't light, fail. If the wires melt and the ballast burns because there isnt a fuse, fail.Arent they generally potted inside? If so, they its not really repairable, so if it doesn't work at its main function then its garbage.A power supply probably wont cut it for testing it out either. The start up ignition surge is large on these. A 5A power supply set at 13.8v failed to ignite a 35W HID I was trying to test, despite 2x the nominal 35W being available. I added a 300mF cap on the output, and it had enough energy in it for it to light though.

author: dog80
author_rank: Regular Contributor
timestamp: September 13, 2013, 01:43:49 pm
content: Yes, it was potted with a black rubbery substance. I tried some solvents but didn't have luck with that. However I managed to get most of it out by hand.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: September 13, 2013, 07:40:56 pm
content: Try roughly 24kV striking voltage. Then rapidly stabilizing down to 48V or 96V (depending on D1/2 or D3/4). The ONLY safe way to test these is using a bulb. In general they are NOT very easy to service. Much of the circuitry is on an ASIC which is unobtanium. If you are lucky you will find a switching device or two. Any reason why you want to repair it, instead of getting a replacement? In general they just are too damn difficult and if you mess it up you can easily start a fire. Also, most ballasts are NOT fused. They rely on a fuse on the headlight line.

author: Kjelt
author_rank: Super Contributor
timestamp: September 14, 2013, 08:53:10 am
content: Yes these ballasts have hot-restrike , meaning they can ignite even a warm HID bulb in seconds and therefore you need >15kV ignition.Comparing to normal street light HID ballast, those have only 2 to 3kV ignition voltage and the bulb had to cool down (3 minutes) before they can be re-ignited.Anyway you are dealing with extremely high voltages in the first seconds here so be very very carefull, better leave it alone or read into high voltage theory first.

author: Zero999
author_rank: Super Contributor
timestamp: September 14, 2013, 01:01:52 pm
content: Quote from: dog80 on September 13, 2013, 01:43:49 pmThen you've probably buggered it.The potting is an important part of the ballast as the PCB clearances are probably not large enough for the striking voltage so you need to re-pot it for it to be of any use.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 14, 2013, 02:26:59 pm
content: Quote from: Hero999 on September 14, 2013, 01:01:52 pmAll the ones I've seen have the igniter as a seperate potted unit - I'd be surprised if there was anything that high on the main PCB, even potted.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: September 14, 2013, 08:53:17 pm
content: Quote from: mikeselectricstuff on September 14, 2013, 02:26:59 pmD1x and D3x have an external ignitor. D2x and D4x have an integrated ingitor. Most D2/4 systems have the ignitor isolated within the ballast but the ignitor is internal and is potted.