Please help me fix strobe light alarm circuit

[spitso]

Hi all

I have a party this saturday and want to add a little bit of lighting effects. I decided to use one of those blue lights off the front of security alarm boxes. It worked fine to begin with (flashing the strobe maybe once every 3 seconds) running on 12v. But i stupidly turn voltage up to 30v which made it flash a little bit more rapidly but of course i heard a loud pop, and didnt work.

I opened it up and saw that a 100µf 12v capacitor had blown, i replaced this but still didnt work. Check all diodes for continuity all was fine a apart from one diode (which had a green band instead of a silver band?)which didnt conduct anymore so i also replaced that (dont know if it was right or not), but still not working. They only thing i can think of that is broken is the transitor but im having trouble working out what i could replace it with, all it says is d789, maybe you can tell what i can replace it with via circuit diagram.

Please help me fix my circuit. below are photos of the device as well as a circuit diagram i ROUGHLY put together.

thank-you

 

[user_88]

NTE Electronics Cross Reference Search

maybe NTE 315

 

[Chippie]

A BD139 would do you or any NPN power transistor with a Vce of around 80-100v and a reasonble hfe...and can dissipate a couple of watts

 

[spitso]

what you think about a bfy51?

 

[Chippie]

what you think about a bfy51?

Try it....should work may need a little heatsink....if it gets too hot

 

[spitso]

no luck. begining to think that maybe it is the transistor thats bad. Ill take it to my tafe teacher tomorrow se what he think about it.

 

[spitso]

teacher was no help.

I am now thinking that another fault is the transformer. Ive tested it with multimeter and their are no broken circuits, but when i apply 4.5vAc @ 0.5A on primary i only get like 0.5V....correct me if im wrong but isnt this transformer meant to step-up the voltage to about +300V AC? Below are pictures of the transformer, dont know what i can replace it with, but i do have a mini audio transformer **broken link removed**

any ideas for next step?