Hi, Newbie here. I hope I'm posting this in the correct forum.

I'm hoping to get some help or advice about how to repair the ballast circuit of my bench magnifier light (here) http://i74.photobucket.com/albums/i280/sacentre/20140926_225250.jpg

It's a no-brand model from an unknown manufacturer in China and looks identical to this one http://i74.photobucket.com/albums/i280/sacentre/BenchMountedMagnifier.jpg. I don't expect the photo will help much.

The store I bought it from earlier this year doesn't sell them anymore and couldn't care less about helping me to get it repaired. I might have just bought a new one if they'd been available.

I'm afraid I'm not very good at fault finding and diagnostics but sometimes I get lucky with guesswork. On this PCB, I can see 2 burned resistors - R2 and R1 (just to the left of the upper SR 6863D). As far as I can tell, the damaged resistors appear to be colour coded red, black, black = 20 Ohms. Assuming someone is familiar with this type of circuit, does that sound right? One side of each resistor is connected to the left leg of the transistor viewed from the front.

I would guess that as well as the burned resistors, the two SR 6863D semiconductors have blown.

Can anyone tell me what the SR 6863Ds are or better still, suggest an equivalent? I've tried Googling for hours but haven't been able to find an information about them. I tried asking at my local electronics store but they didn't recognise the number.

Thanks in advance.

Trevor

 

possibly npn silicon, can you take pics of the track side and a full view of the component side, to redraw the circuit, it looks like a push/pull oscillator


for whats its worth trying to fix it, just get another electronic ballast on ebay.


http://www.ebay.co.uk/sch/i.html?_o...llast&_nkw=fluorescent+light+ballast&_sacat=0

 

Thanks, Dodgydave
It's worth doing if I can get hold of the 2 semiconductors. If that's impossible then it's a different story. Wouldn't mind just buying one but I don't see anything that would fit in the same place as the original.

 

This is the closest thing to a data sheet I've been able to find

http://i74.photobucket.com/albums/i280/sacentre/SR6863DDataSheet.jpg

but it doesn't provide much information.

 

It should work with a MJE13005. See datasheet attached.

Allen

 

Allen, many thanks. I'll see if I can source them and give it a try.

Trevor

It should work with a MJE13005. See datasheet attached.

Allen

 

One way to get the MJE13005's is to go to the store and buy a Compact Florescent Lamp and raid it for the parts. Be careful to not break the glass tube.

A very good resource for troubleshooting electronic ballastas is
http://www.pavouk.org/hw/lamp/en_index.html

 

Many thanks, Dick, for the suggestion and the link. I'll see if there's a make/model that has the device.
Thanks again.

Trevor

 

I have the 1300-5 transistors in a TEC cooler I'm repairing, and I'm replacing them with a part from Mouser, a Fairchild power switching transistor: FJP3305H1TU