Testing magnetic ballast

[perpetual98]

So I've got a 26G bowfront in the master bedroom and it's got a 250W mogul14KK DIY pendant over it. The last couple days the halide hasn't fired up. I've jiggled the wires on the capacitor and it would fire up. Lately though I can't even do that. Is there a way that I can test the capacitor to see if it's shot? The ballast itself is warm, so I'm leaning towards the ballast being ok and the cap being bad.

Any advice?

[dakar]

Got a good digital multimeter? Check the output voltage from the coil, I'd have to double check, it should be around 250VAC, the cap can be tested the same way if your meter can do it (mine does), should be around 15uF, but I'd need to ballast manufacture and part number to be more exact and come up with a current potential from the coil to test for.

Now remember that a capacitor charges up to 66% of it's current potential and releases, charges back up, releases, and the cycle continues, where you interupt this cycle can lead to there being quite a substantial amount of current left in the cap at a stiff voltage, it WILL jump out and say hello if you aren't careful. Best to ground each lead before trying to test it.

Did you solder all your connections? Maybe as simple as cold joint somewhere... if not, break out the iron and get soldering, avoids a lot of troubles.

If there is voltage at the lamp holder, have you tested it with another bulb? I know the little conductor at the backside of mogul bases tends to loose it's springyness (that looks like a word) and can cause intermitant troubles.

[perpetual98]

I haven't broken out the Fluke yet to test it. I also don't have another 250W bulb to try, but that would be the easiest thing to try. I can try to solder the connectors on the cap. I do have that capability. Where should I be measuring 250VAC? Between the cap and the coil? It's an Advanced M58 Ballast if I remember correctly, but don't quote me. I can get that information later when I get home. Are 250W caps specific to 250W ballasts? I might be able to get a cap at work to try it out, but I'm not sure if we have any 250W ones laying around.

[jerryc]

sounds like a lose connection........................................ ...........

Testing a capacitor use a Ohm meter after shorting out put leads across the terminals the Ohm meter will go up and slowly come back to 0 reverse and
do the same if good you will get the same result.
Are if you wont to invest about 20.00 Thea make a capacitor checker.

As already stated Thea can bit real good believe me i got hold of a large
one putting together a pale-phase

[dakar]

Test the coil at it's output (before the cap), the output will be AC. I just checked my Advance H37 ballasts and the cap is rated at 22.5 uF @ 300V. Now the 250w pulse start ballasts I worked on last week had 15uF @ 300V caps, but the pulse starters may be different. Better to get the ballast number to be sure.

I cheat, my meter does capacitance, diodes, hFe (transistors), current, as well as the typical resistance and voltages. Really afraid of the day it dies, I've had it for like 20 years now and don't want to know what it'd cost to replace today.

[jerryc]

[I cheat, my meter does capacitance, diodes, hFe (transistors), current, as well as the typical resistance and voltages. Really afraid of the day it dies, I've had it for like 20 years now and don't want to know what it'd cost to replace today.[/quote]

Like always from 15 to 500 depending on whit you wont I gave 180.00 for the one i have after dropping the last off my ladder i love the newer digital amp/volt/Ohm meters

[perpetual98]

I've got an Advance 7C350P24 cap (I think it's a cap) that I could take home and try if you guys think it would work?

It says 35 MFD 240 VAC 50/60 Hz on it if that makes any sense to anyone

I've also got an Advance 7C550P24 that says 55 MFD 240VAC on it. These both came from HPS ballast systems though.

Won't work?

[dakar]

Looks like the standard for M58 Advance ballast calls for 15uF (MFD) @ 400VAC. Just looked at a few different datasheets and they all use than same capacitor. The Advance ballast part #71A5770 coil has an open circuit output of 300VAC. Think this is the more common M58 mag. ballast in use.

BTW the Cap part number is 7C150P40-R.

That HPS cap would not be a good idea, it'll likely melt down since it's not rated for the voltage.

[perpetual98]

Yup, you're right. I just looked at it. I've got an Advance 71A5790 coil. I'll try some things after dinner if I muster the energy.

[dakar]

I was close, but the 71A5770 and 71A5790 have the electrical specs. Only difference is the 5790 has 12" output leads and the 5770 has spade terminals. Took a few times going over the datasheets to find the difference.