beyond magic smoke has been escapee - Page 1
Forum section: electronics / general

author: hussamaldean
author_rank: Unknown
timestamp: August 16, 2019, 04:00:23 am
content: Hithis is not the magic smoke has escaped, this is the mother of the magic smoke has escapedyour opinion

author: jmsc_02
author_rank: Regular Contributor
timestamp: August 16, 2019, 10:58:16 am
content: I would have turned off the device instead of filming it to catch some anonymous attention and also breathe toxic fumes, but we are living in strange times...

author: hussamaldean
author_rank: Unknown
timestamp: August 16, 2019, 01:02:57 pm
content: Quote from: jmsc_02 on August 16, 2019, 10:58:16 amwell, I was wearing a mask 😷don't worry and I love blowing my stuff

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 16, 2019, 01:41:13 pm
content: Video link appears to be broken or missing

author: hussamaldean
author_rank: Unknown
timestamp: August 16, 2019, 03:53:42 pm
content: Quote from: schmitt trigger on August 16, 2019, 01:41:13 pmhttps://i.imgur.com/QOBrrCu.mp4

author: Cyberdragon
author_rank: Super Contributor
timestamp: August 16, 2019, 04:22:56 pm
content: I'm sorry sir, your board...it just caught fire! There was nothing I could do!

author: MrMobodies
author_rank: Super Contributor
timestamp: August 16, 2019, 06:06:01 pm
content: It looks to be working after that component caught fire at the end of the video.

author: German_EE
author_rank: Super Contributor
timestamp: August 16, 2019, 07:25:12 pm
content: I hate that smell.

author: Red Squirrel
author_rank: Super Contributor
timestamp: August 17, 2019, 03:40:12 am
content: Maybe this is a feature to keep the board at a specific temp for better calibration.

author: hussamaldean
author_rank: Unknown
timestamp: August 18, 2019, 06:14:45 am
content: Quote from: Cyberdragon on August 16, 2019, 04:22:56 pmyup exactlyQuote from: MrMobodies on August 16, 2019, 06:06:01 pmthe IC which burnt was mosfet driver but not sure about the model numberit is smart charger which shows case buying cheap stuff can be really dangerousQuote from: German_EE on August 16, 2019, 07:25:12 pmI love ❤️ itQuote from: Red Squirrel on August 17, 2019, 03:40:12 amthis is how cheap Chinese manufacturers think

author: whershey
author_rank: Newbie
timestamp: October 07, 2019, 02:58:54 pm
content: I recently had an case of magic smoke escaping on an industrial motor control PCB. The board is powered with 24 and 48VDC and controls 4 DC motors.It is somewhat sophisticated having some I/O and CAN interface as well as Hall effect motor feedback. There are other identical PCBs on the same power circuit and CAN bus.After the smoke came out, I measured the motor resistances and they were all around 1.7 ohms. Thinking that this was a case of infant mortality, we replaced the PCB.A few days later the replacement PCB also failed in the same way. I took the PCB out of its mount and as with the 1st, all I could see was black burn marks covering the entire board. There was nothing to pinpoint where the short originated. The power transistors were still covered with their SIL pads. Do you have any ideas on how to diagnose a problem like this? Is it likely that the PCB (the board itself and not the components) was poor quality and caught fire due to the normal operational heat?

author: OwO
author_rank: Super Contributor
timestamp: October 07, 2019, 03:15:31 pm
content: Quote from: whershey on October 07, 2019, 02:58:54 pmThat is extremely implausible because normal reflow goes close to 300C, which your board should not go anywhere near during operation. My guess is the design stresses some part and exceeds maximum ratings (for example exceeding transient SOA). If you suspect the problem is thermal the least you can do is take thermal images of the board after an hour of operation.

author: whershey
author_rank: Newbie
timestamp: October 07, 2019, 03:28:37 pm
content: thermal image is a good suggestion. What is "SOA"?

author: OwO
author_rank: Super Contributor
timestamp: October 07, 2019, 03:57:27 pm
content: Quote from: whershey on October 07, 2019, 03:28:37 pmSafe operating area. All power transistors will have a SOA vs pulse width graph in the datasheet that will tell you the combinations of voltage and current that are safe. Be careful though that this is usually specified at very low duty cycles.