Discussion in 'General Technical Questions and Answers' started by WF7A, Jun 20, 2019.
The other 5% is normally due to the diode getting so hot it melts the solder on the board.
I like the approach from K9YC:
Just an update:
I bought a pack of 1N5248B's from eBay (which arrived today), unpacked my soldering gear, and took to the circuitboard...where within seconds I ruined one of the zener diode's pads. (It would be fair to blame poor circuit board plating--I used a low wattage iron and didn't apply that much heat for anywhere near too long to have caused such damage.) However, there was juuuuuust enough pad left to make an electrical connection with the traces connecting to it, so I was able to install the diode.
I powered up the subwoofer and...no boom, smoke, sizzle or acrid smell. Yay! It just goes to show that when troubleshooting, you can glean good info from the 'net...the Zed included. : )
Thanks again for your help, offers, and info, guys!
Sometimes a higher power soldering iron is better, Because you can get on and get off the PCB a lot faster. Flux is your friend also.
Sometimes applying even a small amount of "sideways" pressure on a PCB pad, with any heat at all, will damage it.
But I agree some PCBs are real junque and most of those are in Chinese made products manufactured by no-name shops that are not qualified to do any work for the big U.S. companies (like Apple, et al) but exist being low-bidder for lots of companies without stringent QA systems. They save money by using 2 oz copper where 3-4 oz copper should be used, and some boards appear to have "1/2 oz copper" or less. I can't believe skimping like this could save more than pennies, but they do it.
Pennies by the 100,000's adds up. (Sadly to say.) You (maybe) or I can "over design," and use far more than necessary in "one off" projects for personal use. But when producing thousands (or more) devices, pennies do count.
ME, I would GLADLY pay a $ or two to get a better quality product, but that is not what overseas electronic producers are willing to provide, but more importantly, NOT what the U.S. companies demand at the lowest price per unit.