My Hobby Light/Magnifier Stopped Working

[mmartell]

So of course I purchase and install a new lamp (circline fluorescent) and nada.

Hmm. Check my old lamp with another fluorescent fixture in another room and of course it's working.

Pull down the ballast out of the hobby light and find a swollen 200v 22uf cap. There are two of them but the second isn't too bad looking.

Bust open a burnt cfl bulb I had around and harvest two 200v 15uf caps (it's all I had!) and unit functions again.

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

Fast forward four years...

The lamp stopped working and again a replacement didn't work either. This time the other cap at C4 had vented but also the fusible resistor at F1 had gone open.

I can't read the colour bands off it (see photos). Can anyone suggest a value for this resistor ?

[budm]

Re: My Hobby Light/Magnifier Stopped Working

https://www.badcaps.net/forum/attach...0&d=1556939673
You can see where the breaks on the spiral wire is.
You can check the resistance between each leg and where the conductor spiral is open and subtract the probe wires resistance of each reading that will give you resistance of one spiral, the do the same for the spiral, then add them up.

[SLK001]

Re: My Hobby Light/Magnifier Stopped Working

What budm said. The colors look to me to be RED, BLUE, BROWN, GOLD.

It would help to know where in the circuit the resistor was. Also, can't you get a value from the fixture in the other room?

[awyatt2]

Re: My Hobby Light/Magnifier Stopped Working

here is what I did to the two I have. no ballast required just wire straight to the bulb and extra light to boot. and no more flickering.

https://www.amazon.com/JESLED-Circli...11&s=hi&sr=1-1

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

here is what I did to the two I have. no ballast required just wire straight to the bulb and extra light to boot. and no more flickering.

https://www.amazon.com/JESLED-Circli...11&s=hi&sr=1-1

You wired 120v straight to the lamp ?

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

What budm said. The colors look to me to be RED, BLUE, BROWN, GOLD.

It would help to know where in the circuit the resistor was. Also, can't you get a value from the fixture in the other room?

I thought there was another band (five band) looks like an outline there but maybe you're right and it's just a four band.

I named the location of the resistor in my previous post, F1. You can see it in pic 3, it has been removed but its position is between the two incoming wires at the top of the circuit board.

There is no other fixture to read the value from. The first post in this thread was from four years ago when it broke the first time and the second post was from yesterday.

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

https://www.badcaps.net/forum/attach...0&d=1556939673
You can see where the breaks on the spiral wire is.
You can check the resistance between each leg and where the conductor spiral is open and subtract the probe wires resistance of each reading that will give you resistance of one spiral, the do the same for the spiral, then add them up.

I see what you're saying bud. I didn't realize the resistive material was so close to the outside of the resistor. I would have thought it to be embedded deeper.

[awyatt2]

Re: My Hobby Light/Magnifier Stopped Working

yes it has a driver circuit built into the lamp. read the instructions ballast and starter must be bypassed. I cant remember what the wires were coming out of the ballast but there were two white and black or red and black tie two of one color two one on the ac line in. its a led light not florescent a lot brighter than the florescent light with less wattage, they live a lot longer and run cooler. I changed over both of mine, one I left the ballast in the base because it simply adds weight to the base. its free standing the other clamps on so I totally removed the ballast.

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

Ok I got ya I didn't notice it was a LED lamp.

[eccerr0r]

Re: My Hobby Light/Magnifier Stopped Working

Since it's F1 it'd more likely be red-violet-gold-gold, 2.7Ω fusible/flame resistant. Thinking about it more, red-violet-brown-gold 270Ω is way too high for the application. It'd have to be at least a black band there.

I'd be more worried about why this resistor failed in the first place...did the transistors short out?

Speaking of these magnifier circline fluorescent lamps, I got one because it was the best way to illuminate a subject with a magnifier - around the lens. I did get it second hand and it didn't come with a tube. So in goes a brand new tube. However what's weird is that I see darkening of the heater area already despite the low number of on/off cycles I've put on it compared to other fluorescent lamps. Weird.

Mine is also an electronic ballast as far as I can tell, does not have the typical startup behavior of a mag ballast auto start fluorescent.

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

https://www.badcaps.net/forum/attach...0&d=1556939673
You can see where the breaks on the spiral wire is.
You can check the resistance between each leg and where the conductor spiral is open and subtract the probe wires resistance of each reading that will give you resistance of one spiral, the do the same for the spiral, then add them up.

I measured roughly 1.4 ohms to each side from the break so minus lead resistance should be somewhere around a 2.7 ohm resistor. That would make it Red Violet Gold Gold I suppose that's possible since the third band is somewhat toasted.

[budm]

Re: My Hobby Light/Magnifier Stopped Working

Yep, that is about right.
So next thing you need to do is to verify that there is no shorted component that caused that resistor to blow.

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

I couldn't find the proper resistor in my parts bin but tried something a little larger in value and the lamp lit but after a few power cycles the resistor went high again. Instead of ordering a proper resistor and at the risk of having further problems in the circuit I have decided to follow awyatt2's lead and do the led conversion.

Thanks for everyone's help.

[awyatt2]

Re: My Hobby Light/Magnifier Stopped Working

its one move you wont regret. I like the light from mine better now than the fluorescent tube anyhow. its a good bit brighter and a lot of ic numbers I couldn't read before I can see now.i have a 3k color in one and a 5k in the other and honestly I cant see any difference plus the 5k was about 15.00 more. I changed out about 2yrs ago, give or take a few months. the reason I did it was from a broken tube, no one knows how it got broken but it was a mess to clean up. there is probally a lot of fine glass still in the cracks of the floor. now I like the light it gives and no more flickering on start, plus I don't have to worry about glass. the sleeve is a hard plastic.

[mmartell]

Re: My Hobby Light/Magnifier Stopped Working

I bought the same one you linked to and since LEDs have a habit of failing prematurely in many cases I paid $4 extra for the four year warranty.

Should get it Wednesday and can get back to the things on the desk needing repair. Thanks for the heads-up it never even occurred to me this was an option.

[awyatt2]

Re: My Hobby Light/Magnifier Stopped Working

so far mine are close to two kicking. I do have a spare pair though just in case. I don't remember what the wire colors were before I changed them out just two same color wires went to one 110 wire, only important thing on the install was the wire colors were right