OK, so I've got these LED lamps, and now the indicators (flashers) don't work right.
So I fitted load resistors short-term, which made 'em flash normal speed.
I then started looking into flasher units - I had a spare one out of an old van, pulled the cover off, and found inside a relay, 3 or 4 components and a chip marked U 643B.
some enquiry produced a datasheet for the U 643B which allowed me to locate the line which does bulb outage sensing, and cut it on the PCB, which meant I had a flasher unit which doesn't sense bulb outage. Fitted it to the vehicle, and it worked, flashers operate at normal speed, even without the load resistors.
Now this vehicle has one of those cute flasher units which also blink a little trailer-shaped light on the dash when you have a trailer connected and the trailer indicator is working, so I'd like to be able to use the original flasher unit, as the one on it now doesn't do that.
And that's where I run into problems, 'cos the IC on this flasher is not a U
643B it's a U 269B... and cutting the track to pin 7 (which is the bulb outage sense on the 643) just results in it not working at all - obviously, the pinout is different. So I've repaired that track, and now I hope it'll work again...anyone know where I might get a data sheet for the U 269B flasher IC? The other one is available from Atmel, who make the U 643B, but they don't list the U 269B. TFK, who actually made the ICs on both chips, no longer exists as a separate entity, and Temic, who apparently bought 'em, don't have datasheets on the web, or not that I could find. I gather that Atmel have a lot of TFK designs, but not the one I want.