400 watt ballast! does this type exist anywhere anymore?

Hi, I recently took apart a 25 yr old 400 watt spotlight and found this old ballast in there. looks pretty ancient i must say. I am going to restore it to its previous state and either build or buy another ballast for it. Any schematics out there or tutorials on this sort of thing?
:smile:

Im using an ipad 2 and it doesnt let me add photos :sad:

so does anybody recommend a reliable 400w ballast schematic? any help appreciated. cheers

You will have to give more details if you want a reply. Most 400W spotlights don't use a ballast at all. What kind of lamp is it and is it the lamp or the ballast that's rated at 400W?

Brian.

This not clear! what are the component of the lamp?

Hey sorry for no pics. Will upload some now

so is this a ballast or ? not sure what im looking at here. coud someone who knows give me an idea what replacement i could use or any infromation to help me move forward in this project?
cheers
Jonny

It *might* be a ballast although it looks more like a soft-start circuit to me. The three pinned device on the right looks like a Triac and the inductor and capacitor on the left look like interference supressors which ties in with it being a Triac because they cause electrical interference. The other components look more like a dimmer circuit without a control. If the orange component is a thermistor, it could be designed like a dimmer but one that automatically turns the brightness up as the lamp gets hotter. This would result in it taking a short while (maybe only a few seconds) to reach full output. Some lamps don't like sudden rushes of power so maybe that's the purpose of this circuit.

Can you read part numbers on the Triac and the orange component?

Brian.

Hi Brian. Thanks for helping. The triac reads PH BT137 500 E8031 and the orange one has no markings on it. However the bottom half of it is white. Also a small chunk of pcb is missing where a diode used to be (about 5mm or so).
cheers
Jonny

My friend Metal-Halide can use ballast 400W and more, even 1KW and more.

**broken link removed**

Ballast often must be used for lots of bulbs to limit current in circuit. Ballast must match to its lamp, both in watts and in volts. One ballast per lamp is required (except for ballasts for multi-lamp fluorescent fixtures. Ballast performs "jump-starts" the gas-discharge lamp and it stabilizes the current once the lamp is started.

DONT PLAY TO START BULB WITHOUT BALLAST !!!!


http://reefkeeping.com/issues/2007-03/sj/index.php


http://en.wikipedia.org/wiki/Electrical_ballast


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Use protective googles if you whant to start without ballast, I dont recommend that and its very dangerous.

Pressurised bulbs are far from simple devices. :wink:

tpetar's picture is more typical of a ballast device although electronic versions exist. It's as large inductor which uuses it's reactance to limit the lamp current. The capacitor is there only for power factor correction, it doesn't play any part in the lamps operation.

The BT137 is a triac, rated at 500V and 8 Amps, made by Philips. The numbers indicate it was manufactured in week 31 of 1980 so it gives some idea of how old the lamp is. I'm going to guess the orange and white component is a thermistor and it works just like a domestic light dimmer but does it automatically. If I'm right, as the thermistor warms up (heat from the triac and lamp) it has the same effect as turning the brightness control up on a conventional dimmer. So when cold the power is limited and the lamp "soft starts", dim at first then slowly increases to full power. If full mains is applied directly to a cold Halide lamp it can cause them to explode.

Modern systems have an additional protection that soft-starts them every time the power is cycled, even if it was only interupted for a moment. You must be careful with yours because if the thermistor is still warm it may not limit the current enough. It all depends on which cools down fastest, the thermistor or the lamp itself.

Brian.