# blows light bulbs



## point1st (Dec 10, 2020)

Motor City said:


> Most lights are AC 120 volts. So you would either bite the bullet and buy the OEM, or convert to an LED. See the LED thread in the Discussion section. I would determine what voltage your machine is generating, AC or DC, first.


I have a TB 3090 XP, the replacement bulb I put in blew immediately. I know the number I got off the original was a familiar 12 v dc auto bulb but after the replacement blew I checked the voltage and there basically is no dc voltage but it has 22 v ac on high throttle. Anyone know if this is normal? Can not seem to get an answer out of TB. TY


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## 140278 (Aug 27, 2020)

welcome to the SBF

you posted this to a 5 year old dead thread i have moved it into the proper troy buit area so you can get some advise where by in the craftsman area in a dead thread you wouldn't


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## deezlfan (Nov 8, 2017)

First thing I look for when I encounter repeated blown bulbs is a bad ground. Incandescent light bulbs don't care whether they run on AC or DC but they are sensitive to variations in voltages.


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## tabora (Mar 1, 2017)

point1st said:


> it has 22 v ac on high throttle


Be sure that the bulb is rated for at least 30V. What's the part number on the original bulb? The Troy-Bilt part number is 925-1629.
You also may want to consider replacing it with an MTD LED upgrade bulb that replaces the bulb and holder: Genuine MTD 925-06095 HEADLIGHT ASM LED | eBay


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## point1st (Dec 10, 2020)

tabora said:


> Be sure that the bulb is rated for at least 30V. What's the part number on the original bulb? The Troy-Bilt part number is 925-1629.
> You also may want to consider replacing it with an MTD LED upgrade bulb that replaces the bulb and holder: Genuine MTD 925-06095 HEADLIGHT ASM LED | eBay


Hi I don't have the original bulb anymore but I seem to remember that when I took it out it was a common number used in auto's and that's what I replaced it with. I used the blower during the day and then when I used it that night it wasn't working. I put in another and blew right away. I said I will deal with it later as I was busy. Some people said maybe regulator was putting out to much voltage and I was tying to get a schematic from TB or service manual but that's like pulling teeth. I checked voltage and has no dc but has ac, 22 doesn't seem that high. I am interested in that led option you mention. does it go where the light normally would or is it a add on somewhere else? Does it use same connector? TY for your help


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## PlOM (Nov 12, 2020)

The linked 925-1629 listing shows it to be an 1141, which is rated 12 V, 18 W.

If the 22 V AC was measured with a typical multimeter, that's supposed to be equivalent "rms", i.e., the same as 22 V DC. Consequently, the 12 V bulb is being run at 22 V; it's not going to last long at that level. Troy-Bilt installs a 12 V bulb for that light, I suspect the applied voltage is supposed to be less than 22 V.

Perhaps someone here knows what machines using 12 V auto bulbs supply. I don't have a Troy-Bilt, but it apparently uses a similar bulb; I'll see if I can get in there for a measurement tomorrow.

I wouldn't plug put in an LED equivalent under those circumstances until the 22 V is verified.


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## tabora (Mar 1, 2017)

point1st said:


> Does it use same connector?


It should replace the bulb and the connector:

















PlOM said:


> I wouldn't plug put in an LED equivalent under those circumstances until the 22 V is verified.


Here's the A/C voltage graph from my Honda HSS1332AATD going to the factory LED bulb. Even higher output levels. Honda's LED unit is rated for 32VAC, so I keep the RPMs well below 4000 at 3750 max.


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## PlOM (Nov 12, 2020)

tabora said:


> Here's the A/C voltage graph from my Honda HSS1332AATD going to the factory LED bulb. Even higher output levels. Honda's LED unit is rated for 32VAC, so I keep the RPMs well below 4000 at 3750 max.


Interesting. 

I was referring to when replacing the incandescent 1141 with a direct replacement auto LED bulb, which would also be rated for 12 V. If the Honda LED is rated for 32 V AC, then no problem.


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## PlOM (Nov 12, 2020)

PlOM said:


> I don't have a Troy-Bilt, but it apparently uses a similar bulb; I'll see if I can get in there for a measurement tomorrow.


Turns out, mine's not the same bulb. 

But for reference, the 1141 in the Troy-Bilt is a basic, 12 V, incandescent automotive bulb with a bayonet base.










My light is equipped with a #890 halogen bulb.










At ~3450 rpm, there's close to 12 V AC at the bulb (bulb installed), and with bulb disconnected, it's about 17 V AC. That should be okay. If the measured 22 V AC in the first post is without the bulb (i realize now it probably was), then that might drop down closer to the 12 V operating range when the bulb is installed.


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