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Ballast question

Track T-4

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Supporting Member
I noticed one of the ballasts on my engine (there's 2 ballasts) seemed especially hot when running and seemed to have what appeared to be a wisp of smoke coming from it. What would cause that? I never noticed this before. Do they normally heat up? The other ballast seems okay.

I spent the past couple of days cleaning up some of the wiring and replaced the old non-functioning SW gauges with new AutoMeter. The battery was dead so I had to jumpstart it. The Voltmeter is showing 14-15 volts when the engine is running which I assume is due to the low battery (12 volts before starting).

I noticed the ballast getting hot when I was checking the oil/water sensors for leaks. Your thoughts? Thanks.
What are the ballasts running most new stuff doesn't require ballasts. I had one running my old point coil now have HEI no ballast needed.
The engine is a 2.3 4-cylider Escort/Pinto. Not sure the ballasts are used for but believe this engine had them originally.
The engine has a Mallory Unilite and a Mallory Promaster Coil Box. I'm not much of an electrician (guess that shows).

I don't think I changed any of the ignition wiring. The PO only had an in-line fuse to the elec fan and a fusible link to the key switch. There was a direct hot from the key switrch to the light switch and everything else ran off the key switch. I changed the hot wire that ran to the light switch and ran it from the accessory side of the key switch to a new fuse box, that way nothing works without the key. Then I ran everything (light switch, horn, fan, etc.) offf the new fuse box.

Don't understand why the ballast is getting so hot. :confused:
It's a little difficult to tell. The PO had a habit of reusing the same color wires, splicing colors together and/or not following a color code (a total rewiring project is in my future).

As I said, there are two ballasts. Ballast #1 has two wires attached to the left side and one to the right. One wire on the left and one wire on the right go to distributor (Mallory Unilite). The other wire on the left side goes to the left side of ballast #2.

Ballast #2 has one wire on the left and two on the right. The left wire is the one from ballast #1. One wire on the right has a wire that disappears over the trans with a few wires of similar color, the second is yellow and I believe goes to the master cylinder brake switch (I have to double-check this tomorrow).

Ballast #2 is the one that gets hot.

I also replaced the master cylinder and the brake switch. Could I have done something wrong there that might cause a problem at the ballast? I'm still not sure I understand the purpose of the ballast. Does it make sense to have one attached to the brake wiring? Or maybe I'm wrong on where that wire is going.
I think I would disconnect the balast that is getting hot and look for something that doesn't work. Your car is to nice to burn up because some clod messed up the wireing. If everything works, drive it until the winter and pull all the wireing out and redo it......or give to a round fart from Georgia. Come to think about it, that is the best fix of all!
Ballast resistors are used in series with devices to limit the current through them. The most well known is the ballasted coil, the ballast resistor limits the coil current (and therefore temperature) except when cranking.
LED lights need a ballast resistor to limit current through the diodes but duzzen sound like you gottem.
I dimly remember a few rear light setups that used a ballast resistor for the rear lights and by passed the resistor to give bright stop lights. On what I don't remember.
Sounds like 'Ol Smokey is connected direct to ground with nothing to limit his current - he's a fire hazard, so first up, disconnect him. He's probably killing the battery too.
14-15 volts is a bit much for your alternator, maybe that for a minute or two but then I would expect 13.5 - 14 tops. High voltage kills halogen lamps as well
Wild Mango,

Food for thought. I didn't mention that I added six LED lights to the dash but only two are connected (four for future use). One LED is blue and was attached to the hi-beam post on the light switch to indicate when the high beams are on. Second LED is a red blinking light (cheap theft avoidance), this is the only electrical thing that will work when the key is has an 5-amp in-line fuse and works through a toggle switch. I noticed the blink was bright at first but after a while it has dimmed considerably when turned on.

A while back I also added a license plate frame with a LED third brake light that is tapped into the brake light circuit but didn't notice a problem when that was added.

Are you saying I need to add something to the LED circuits on these? If so, how? Could these be the cause of the problem?

Made some progress today, here's where I stand with this problem right now:

A friend who is more electrically-inclined stopped by today. He confirmed that all of the power and ground hook-ups I did are good and everything I wired appears to be fine (I'll have to get a photo).

We've come down to two conclusions - the ballast that is heating up is going bad OR is not required. According to the Mallory electronic distributor and Promaster coil 28720 installation instructions, only ONE ballast is required and the points distributor requires TWO. I have the electronic ignition so dont know why they have two ballasts unless the PO just didnt eliminate one when he switched to electronic ignition. So I'm shooting an email off to Mallory technical tonight and ask what they think I should do. Otherwise, the hot ballast seems to closely match the specs of the other ballast. I might get a second ballast in the morning and see if it gets hot, depending on the reponse from Mallory.

Is the ballast bad? We're getting about a 5 volt drop on the first (hot) ballast and a 3 volt drop on the second. Not sure why they are different. The ohms for both appear to be close to each other and the range of the specs (1.7 for the hot one - a little high - and 1.4 for the other, the specs range is .75 - 1.5 ohms). We're thinking the hot ballast might be going bad - if in fact, two ballasts are required. Okay, so the specs are close, then how hot is too hot? I know I cant touch it or risk a burn and that is after only about 2-3 minutes of the engine running. Plus the hot one is wire-tied to the oil dipstick - guess I need to make another bracket. The other coil remains "touchable". I'm concerned about a meltdown but am not sure what else to do unless Mallory has an answer.

BTW, the fading blinking LED was a bad connection so unrelated. :lol:
I would try a different ballast if it ran fine before . The resistance on the one is a little high which will drop voltage and cause heat.
Putz....I took your advice and replaced the ballast that was getting hot. . I have a gauge that checks surface temperature (cheap at Harbor Freight) so took the car out for a drive then checked the temperatures. Both ballasts were about the same, around 100 degrees which is pretty good and not hot enough to burn your hand. So I think that solves the problem.

I haven't reduced to one ballast yet, sent an email to the Mallory technical staff and am waiting for their response. I'm pretty sure they are going to tell me I can go down to one in which case I will eliminate the other old ballast.

The last problem we found late this afternoon was the regiulator wasn't grounded very well and the voltmeter was showing almost 16 volts. Made a better ground and now get 14.4 volts with charging a low battery so I'm happy with that. We have a total of about 12 miles driving this car - that's in three separate trips in almost a year - unbelievable. Took it for a drive after dinner - about 15 miles and, with some stoppng, the temp only got as high as 180 but usually dropped down to about 170-175 so that's better.

I think we're ready for the NSRA East Coast Nationals in York, PA this weekend. Tons of streetrods and we could use a few more T-buckets. This is our first outing......I'm psyched! And then it's off to Lenoir.

Thanks for the feedback Putz, Wild Mango and Old Round Fart.
Any time now put some miles on that ride!!
Hi Bruce. LED's are diodes that happen to emit light. They need some resistance in series with them to limit the current otherwise they burn up or burn extra bright at first and then dim off as the heat kills them like one of yours sounds like doing. You can google an LED resistance calculator. Some automotive LED's already have the resistance built in. I suggested the ballast in question was once a resistor for am LED tail light array.

That don't sound like your problem though. The ballast you have is perhaps getting hot because it is connected direct to ground instead of through some device. I would disconnect it and see what stopped happening. Your coil should only need one ballast of about 1.2 to 1.6 ohm give you say 7V at the coil + terminal running. However, thats assuming your ignition needs one - most "electronic" ignitions (including the venerable HEI) don't use a ballast resistor, they limit coil current by controlling the charge time.

14.4V is right on the money for your alternator, you might check the engine block has a good ground connection too.

Happy tinkering!..........

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