Atlas 550 power supply fuse keeps blowing after new DALLAS battery clone installed on board.

[wreardon]

  The Dallas battery chips were failing on three of our Atlas 550s.  I bought TI bq4287MT-S82 replacement chips. We tried replacing the bad chip on one board, but had no luck.  The remaining two boards were sent out to be soldered. The boards came back and I reassembled the chassis. Now when I turn the power on the 250VT2AL fuses blow. I'm pretty sure I reassembled correctly. I verified against pics. I checked the power cable. Is there possibly something I'm missing or are these resoldered boards no good at this point? Or possibly the chips?

[Anonymous · Accepted solution]

I'm afraid there's no advice I can give to ensure you reassembled the device correctly. As I recall from when I took an ATLAS apart in order to view the U4 Dallas Chip; I believe I only had to remove the one circuit board, so reassembling it was quite easy. I didn't remove the U4 chip, but did verify it was through-hole, and not surface-mount. So if nothing else, you should be able to look at the circuit board on a working ATLAS 550 and verify how it needs to be reassembled.

From what you wrote, I'd say there is a short somewhere. If it is assembled correctly, I would first make sure nothing on the new chip has a solder-short. Also ensure the chip is installed with the correct orientation.

I'm afraid this is about all I can suggest,

Patrick

[jayh]

Make sure the chip isn't installed backwards.

If you ever have to do this again, I highly recommend replacing the chip with a socket. This makes it a lot easier next time.

[wreardon]

Patrick - Thank you.

[wreardon]

Jay - Yes, thanks, the orientation looks good. I'm wondering if the chips are no good.  I have a few more chips and another unit that needs a battery. I'll look into replacing with a socket. I'll do it myself (no point in spending $ to send it out and have it not work when I can do that myself!) and experiment on the boards that are blowing the fuses.   I am fairly mechanical. I sent the boards out because I was put off by the tight tolerances. Thanks.