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Author Topic: MTR Scare!  (Read 6861 times)

gil

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MTR Scare!
« on: March 28, 2014, 02:09:51 AM »
I just about croaked tonight... Well, not literally, when my beloved Weber MTR puffed out a cloud of foul smelling smoke! There was a popping noise as well. I unplugged it and opened the case, expecting a big mess in there, given the amount of smoke that came out. Nothing! No burnt traces or components, no visible damage. I checked everyting, power plug, etc. The smoke seemed to come from the front, between the PCB and the top of the case. Finding nothing, I plugged it back in, it works! Proceeded to call a station in Morocco, who answered my first call! There were many other stations trying.. WTH?

I've never experienced anything like that. I'm not complaining mind you, I would have been very upset if my MTR had died, more upset than if my KX3 blew up.. :-\  (I'd be pretty upset too..). I wasn't even touching the darn thing, just had my earphones on.. Voltage was 11.4V, so no trouble there. It's a mystery! It still smells aweful...

Well, time to go to bed. I'll try the MTR again tomorrow. I want to take it with me camping this week-end...

Gil.
« Last Edit: March 28, 2014, 09:46:03 AM by gil »

cockpitbob

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Re: MTR Scare!
« Reply #1 on: March 28, 2014, 07:53:44 AM »
Get a magnifying glass and look carefully at the big capacitors.  Something in the radio went short then cooked itself into an open circuit.  It's not guaranteed to stay open though.

Good luck with it!

KK0G

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Re: MTR Scare!
« Reply #2 on: March 28, 2014, 08:29:30 AM »
I agree with Bob, something definitely cooked in there and my guess is a capacitor. Time to get out your magnifying glass and check it all over very closely, fortunately you don't have much to check with such a small PCB.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

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gil

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Re: MTR Scare!
« Reply #3 on: March 28, 2014, 08:56:16 AM »
Hello, I agree on a capacitor.. Not much else that could do that out of those tiny surface-mount components. They all look spotless though.. The front I think is the only side with electrolytic capacitors, three maybe.. I could change them all I guess.. I posted on the AT-Sprint Yahoo group and asked for advise..

Gil.


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« Last Edit: March 28, 2014, 09:47:23 AM by gil »

KK0G

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Re: MTR Scare!
« Reply #4 on: March 28, 2014, 10:50:33 AM »
The best diagnostic tool I've used to locate burnt components is my nose, probably a little more difficult tool to use in your situation though with such a small board. Might help to verify though once you remove the suspect(s) from the board.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

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gil

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Re: MTR Scare!
« Reply #5 on: March 28, 2014, 10:53:16 AM »
Quote
The best diagnostic tool I've used to locate burnt components is my nose, probably a little more difficult tool to use in your situation though with such a small board.

Yep, tried that, too small... One guy on the AT-Sprint group says it wouldn't be a capacitor but likely a final transistor. I doubt that since the smoke was coming from the other side and I wasn't transmitting. And of course since I have 20 spare transistors, it won't be that. However I have no spare capacitors, so it's most likely  ::)

Gil.

KK0G

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Re: MTR Scare!
« Reply #6 on: March 28, 2014, 11:20:10 AM »
If it does end up being a capacitor you don't have, let me know. I have a decent stock of them and would be happy to drop one in the mail.
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

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gil

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Re: MTR Scare!
« Reply #7 on: March 28, 2014, 11:34:34 AM »
Thanks Chris. Those are tiny elctrolytic capacitors, the size of a pea.. I'm sure Mouser has them for peanuts.. The MTR works just fine though, but I feel a bit weird about leaving it like that after that incident..

Gil.

cockpitbob

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Re: MTR Scare!
« Reply #8 on: May 29, 2014, 09:28:13 PM »
So Gil, what ever happened with your smoking MTR???

gil

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Re: MTR Scare!
« Reply #9 on: May 29, 2014, 09:49:30 PM »
Well, nothing! All functions work properly and I have the same power output. As if it never happened :o So I am leaving it at that..

Gil.

cockpitbob

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Re: MTR Scare!
« Reply #10 on: May 29, 2014, 10:55:08 PM »
Most engineers just throw "plenty" of capacitors into their designs.  Only if it's going to fly into space or have millions made will an engineer take the time to determine how much power supply bypass capacitance is really needed.  My only concern is that something that smoked and blew open circuit could some day decide to go short circuit.  But that probably would have happened by now.  I'm glad this didn't happen to me.  It would drive me nucking futz not knowing what let its smoke out.

KK0G

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Re: MTR Scare!
« Reply #11 on: May 29, 2014, 11:54:42 PM »
Most engineers just throw "plenty" of capacitors into their designs.  Only if it's going to fly into space or have millions made will an engineer take the time to determine how much power supply bypass capacitance is really needed.  My only concern is that something that smoked and blew open circuit could some day decide to go short circuit.  But that probably would have happened by now.  I'm glad this didn't happen to me.  It would drive me nucking futz not knowing what let its smoke out.
When I first started to learn electronics (and believe me I still have a LOT to learn) I could never figure out what all the .01 capacitors in a schematic did - here's one, there's another one, and yet another, hey what's this one over here? I couldn't really see what they were for because from my meager electronics knowledge it sure looked like the circuit would work just fine without them. Sometimes the author of an article would even suggest adding more bypass capacitors that weren't shown on the schematic. Maybe some of these guys were heavily invested in capacitor factories? ;D
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin

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mdmc

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Re: MTR Scare!
« Reply #12 on: June 07, 2014, 01:17:02 AM »
It sounds silly, but you can use a drinking straw to sniff through and isolate the area somewhat. You can cover the nose end with a piece of pantyhose material or something similar to protect yourself.

gil

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Re: MTR Scare!
« Reply #13 on: June 07, 2014, 01:25:25 AM »
Yep thanks, tried that.. Nothing found.. It's been a while now, and the MTR works flawlessly, so I'm not going to bother..  ::)

Gil.

cockpitbob

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Re: MTR Scare!
« Reply #14 on: June 07, 2014, 09:57:29 AM »
Old electrical engineers remember Mad Man Muntz.  An off-beat entrepenure.  One thing he did was make TVs cheaper than anyone else.  They wouldn't work out in the country with weak signals, but most people live in the cities where the signals are strong.  His method of reducing cost was simply to remove a part and see if the design still worked.  If not, he'd put it back and try another.  A method dubbed "Muntzing" the design.  Your MTR Muntzed itself.   8)

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Re: MTR Scare!
« Reply #14 on: June 07, 2014, 09:57:29 AM »