LED strobe controller IC replacement

[lilmatt119]

Hey there everyone, new guy to the forum, and Brand new to ICs. I've been playing with basic 12v electronics and LEDs for years. I have an LED strobe setup similar to many others mentioned in older threads (specifically where they were building their own control units). My situation is a tad bit different. I wish to use the factory control box, but the chip it has is having issues, sometimes it will work normally, other times the LEDs go to steady on, and other times I don't get anything. Here is my problem, even after many hours of research and buying a few different ICs, I can't find one that works correctly. My first thought (again after a lot of research) was a 556 timer. So I grabbed a socket and a 556, and got diddly. It is a 14 pin chip, but I have not been able to ascertain anything further even after googling the limited markings. I will be uploading a picture in a couple hours when I finally get home. Any help will be appreciated.

For further info, the box controls two outputs of LED units, for a total of 6 units, each with 3 LEDs. The LEDs are yellow/amber, and are wired in series with a 68-Ohm resistor. They receive bursts of 12v for the time they are on. The controller has three available alternating patterns. Pattern A: LED1 flash three times, then LED2 flash three times. Pattern B: LED1 and LED2 flash once at same time. Pattern C: LED1 flash once then LED2 flash once.

I do have a multimeter and can try to get any further values needed tomorrow. My only real concern is finding a 14-pin IC that will give me three available patterns (at least one with multiple quick flashes like the Pattern A) without any further modifying. I am not concerned that it be the exact same patterns or the same arrangement. I just need flashing lights lol. Thanks for any and all help.

 

[lilmatt119]

Here is the pic. Obviously that the 14 pin IC in the center.

 

[hevans1944]

The picture tells us nothing. Please take a close-up photo of the 14-pin IC showing the factory markings. This may not help much if this is the only IC on the circuit board. There are probably some power transistors too that actually provide current to the LEDs, but a picture of the bottom side of the circuit board does not reveal where they are or how they are connected to the IC.

There are plenty of EMS strobe flashers on the market, some at very low prices. You should consider purchasing a new one. Here is one that flashes LED1 eight times, then LED2 eight times, alternately and continuously. It also alternately flashes LED1 and LED2 continuously. And it flashes LED1 and LED2 simultaneously and continuously. All this for less than ten bucks American plus free shipping from Amazon. Only difference I can see between this unit and your unit is eight flashes instead of three.

BTW, there are a zillion 14-pin ICs out there. All different. The one you have may be a special OEM (Original Equipment Manufacturer) version that is not sold to consumers or end-users, hence cannot be replaced. Sorry 'bout that, but that's how some people protect their IP (Intellectual Property). Many of us here could show you circuits you can build from readily available parts, but I suspect that is not the road you want to travel. Replace it may be your only option.

 

[lilmatt119]

What's funny is I actually have that same box running another set of lights lol.

I will get you a picture of the component side tomorrow and also the IC by itself, as the only markings are on the underside.

Later down the road I may decide to build my own controller circuit to run all the lights I have from a single place, but I just want to get the lights installed and running for now lol.

 

[hevans1944]

Is this by any chance an automotive application? Hazard warning lights for a tow-truck perhaps?

 

[lilmatt119]

It is for my car, I use it to run volunteer fire calls and do security work. I originally got these sets of lights just to use until I figured out what I wanted, but it's quickly turned into a project to make them better and for me to learn, so yeah.

 

[hevans1944]

Well, don't feel alone out there. There is plenty of help available here when you are ready to try building your own strobe controller. Flashing LEDs is one thing though... flashing headlights is more effective, but much harder because of the way incandescent lamps behave electrically (high inrush currents when cold). We can help with that too when you are ready to go there. Note that IMHO it will always be cheaper to buy than to build because these are high-volume products sold world wide. Caveat emptor though: there is a lot of junk out there too at low prices.

 

[lilmatt119]

You are correct sir. However, modulated headlights are illegal for anyone but law enforcement here in NC.

 

[hevans1944]

You are correct sir. However, modulated headlights are illegal for anyone but law enforcement here in NC.

Oops! I didn't know that. They are probably illegal in all states for anyone except LEOs.

Oh, no "sir" is necessary. We're all "just folks" here. You can address me by my nickname, Hop.

 

[lilmatt119]

I know they are in several states, not sure about all states, though if I had to guess I would say probably so.

As for the "sir", thank you. However, expect to see it again as I sometimes like to talk a little more eloquently. It's just something I do every so often.

And as for the picture of the component side, I have one from earlier this week, but I forgot to get a good one as I got wrapped up in other parts of the project yesterday lol. I will add the picture that I do have and will make a point to get a better one tonight.

 

[hevans1944]

Pretty good picture but it confirms my suspicion that the 14-pin chip is probably an application specific integrated circuit (ASIC) and is probably unobtainable. Note there is provision on the circuit board to add two more "882" power transistors (whatever those are!) so there are probably other models available from this manufacturer, perhaps one that provides A, B, C LED circuits for ambulances. Note the 5.1 V zener diode used to drop vehicle battery voltage down to the level typically used for TTL (transistor-transistor logic) ICs. You might want to check with your VOM that this diode does provide 5.1 V across it when power is connected. If the diode is open the 14-pin chip will get fried when the 12 to 14 V vehicle battery voltage is applied to it. As I mentioned earlier, I think your "best" option is replace the whole thing instead of trying to repair it. You might want to salvage the two power transistors and other components if you want to pursue electronics as a hobby.

 

[lilmatt119]

It does drop it to 5 V, I accidentally verified that while trying to figure out the problem haha. I am familiar with mostly very basic components, so I only knew that was a diode of some sort but not exactly what.

To the salvage box it will go then. I already have a stash of a few kinds of components, so I will add these in. Luckily I planned on ordering several more of these sets so it is not a great big deal. I can strip all the output wiring off and take my socket back as well lol.

Thank you again for your help! Indubitably, I would still be scouring the interwebs looking for a replacement, if not for you!