Results 1 to 12 of 12

Thread: "Blown-up" Active Components

  1. #1
    Member
    Join Date
    Oct 2011
    Posts
    54
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    8

    "Blown-up" Active Components

    Just curious, has anyone experienced an active component (transistor, IC, Diode, etc.) that "blew-up" or exploded? I am working on an amplifier where a large transistor (TO-247) and a smaller SMD Diode look like part of the case has fragmented and departed the device. I have seen plenty of active components "burn-up". However, these have broken apart without any sign of smoke or burning. Does anyone know what can cause such an odd occurrence?

    0 Not allowed! Not allowed!

  2. #2
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,154
    Thumbs Up/Down
    Received: 2,204/4
    Given: 2,514/0
    Rep Power
    30
    Without a shematic I can't really say what may have happened. But suffice to say that something on the current drawing end of that circuit tried to draw too much current.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  3. #3
    Noodle of Reality Steve Conner's Avatar
    Join Date
    May 2006
    Location
    Glasgow, Scotland
    Posts
    7,251
    Thumbs Up/Down
    Received: 13/0
    Given: 0/0
    Rep Power
    23
    Like this?


    It's caused by a really massive overload vaporising one of the bond wires. The resulting cloud of superheated gas blows the package apart.

    In the above case, the culprit was a 3300uF inverter grade capacitor charged to 400V. I found pieces of the package 10ft away. Large filter capacitors in solid-state amps can have a similar effect, but less spectacular.

    0 Not allowed! Not allowed!
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  4. #4
    Old Timer J M Fahey's Avatar
    Join Date
    Oct 2007
    Location
    Buenos Aires, Argentina
    Posts
    11,753
    Thumbs Up/Down
    Received: 1,877/23
    Given: 1,463/35
    Rep Power
    27
    Yes I have, *many* times.
    Big plastic transistors as shown above, smaller TO220 ones, diodes, you name it.
    Cracked or with parts missing, probably in orbit.
    EDIT: most cases accompanying a *really* big fuse in the fuseholder, a piece of aluminum foil or it being bypassed by a piece of wire.
    Saving on a 50 cent fuse usually increases the repair price by $50 to $200.

    0 Not allowed! Not allowed!

  5. #5
    Bent Member Chuck H's Avatar
    Join Date
    May 2007
    Location
    pacific north west
    Posts
    15,154
    Thumbs Up/Down
    Received: 2,204/4
    Given: 2,514/0
    Rep Power
    30
    Quote Originally Posted by J M Fahey View Post
    most cases accompanying a *really* big fuse in the fuseholder, a piece of aluminum foil or it being bypassed by a piece of wire.
    Saving on a 50 cent fuse usually increases the repair price by $50 to $200.

    0 Not allowed! Not allowed!
    "Never bet your life on somebody else doing their job." SoulFetish's good friend

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "Being born on third base and thinking that you must have hit a triple is pure delusion!" Steve A

    "Back to the amp. It makes horrible sounds when I play my guitar thru it... because I suck at playing guitar." Mike6158

  6. #6
    Member
    Join Date
    Oct 2011
    Posts
    54
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    8
    Replying to Steve Conners' question "Like this?"
    In a big way, yes! But partially no. The damaged transistor in your image looks very similar to my transistor, however, my transistor did not show any sign of smoke. Perhaps a sudden rush of VERY high current made the transistor shatter before it had a chance to blacken the leads or surrounding area?

    0 Not allowed! Not allowed!

  7. #7
    Old Timer J M Fahey's Avatar
    Join Date
    Oct 2007
    Location
    Buenos Aires, Argentina
    Posts
    11,753
    Thumbs Up/Down
    Received: 1,877/23
    Given: 1,463/35
    Rep Power
    27
    Minor matter.
    It's dead anyway.

    0 Not allowed! Not allowed!

  8. #8
    Old Timer
    Join Date
    Jun 2007
    Posts
    5,105
    Thumbs Up/Down
    Received: 90/0
    Given: 57/0
    Rep Power
    19
    If the transistor is securely bolted down to the heatsink and the leads are securely soldered to the board, it could have been a rapid temperature change of the case that caused it to shatter.

    0 Not allowed! Not allowed!

  9. #9
    Member
    Join Date
    Oct 2011
    Posts
    54
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    8
    Replying to J M Fahey:
    Actually, it DOES matter to me. Thus the reason for my original post.

    I now believe if a component "blows-up" without smoking or burning, it may be the result of another component that can quickly cause very high currents to flow through the failed device. If, however, a damaged component shows signs of smoking or burning, it may have been caused by another component that is less capable of large current flow.

    0 Not allowed! Not allowed!

  10. #10
    Member
    Join Date
    May 2011
    Location
    Manchester UK
    Posts
    68
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    9
    It matters to me too. We are really just electronic detectives. Every symptom is a possible clue that might lead us to the principal culprit. Sometimes we convict the innocent along the way. So, yes, an exploded component could well steer you in the right direction. We all look at a blown fuse to see if it blew or REALLY BLEW. Without even realising it, we use that information to decide on the next step. We use touch, temperature, visual inspection, any manner of audio clues and smells to supplement our, documentation, test equipment and of course experience. I have seen a few DIL 8 pin ICs that have blown their tops off and big plastic transistors too.

    I learned a valuable lesson in using every sense for diagnosis when I was 13. I was upgrading a valve radiogram as one of my very first paid jobs. In the process, and too my horror, I managed to blow it up. My father walked in to our workshop and diagnosed the fault just by the smell. I will never forget the smell of cooked selenium rectifier.

    I openly admit to having limited knowledge of valve equipment. Valves were on the way out of the BBC when I joined as a graduate and it was just easier to let the older engineers deal with the the very few faults that arose. I wish now that I had picked up more of their knowledge. We youngsters were too excited by the very first digital national audio distribution system which, in 1981 when I joined, was just going from 13 bit to 16 bit using a new BBC invention called NICAM.

    0 Not allowed! Not allowed!

  11. #11
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    31,873
    Thumbs Up/Down
    Received: 1,726/7
    Given: 0/0
    Rep Power
    54
    SOmetimes they shatter, sometimes they don't. In my years of troubleshooting, I can;t recall finding that difference particularly helpful in diagnosing failures. In other words, don;t over-analyze it. Just my opinion. SHorted/open transistors are just that.

    WHy would a part shatter this time and not another? Who know? SO many variable factors enter into it. When the fault occurred, what the mains cycle at a peak or near zero crossing? If the amp was in use, was there a transient when the failure occurred? Was ther a fault on the load? A load problem could be the cause of the failure, or it could be something about the load made the failure more intense, even though the load itself was not at fault. For that matter, was the output signal at peak or near zero crossing? Was there a mains spike at exactly the wrong instant for this amp. Had the parts been weakened/damaged/compromised by some earlier trauma. Many things can stress a part without killing it, but it leaves the part weakened. A static discharge on the speaker cord, you wouldn;t have felt anything, but the output circuitry sure could have. And then a month later the output stage fails "for no good reason."

    So if my output transistor is simply shorted, I will check its resistors, and the drivers and their resistors. If the output transistor is blown apart, I will check its resistors, and the drivers and their resistors. One piece of shop philosophy we have is "never think up reasons not to check something." SO there is no case where I would say to myself, "this part failed but didn;t shatter, therefore I'll not bother to check XXX." When they blow apart, there are no extra things to check, we check all the things regardless.

    0 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  12. #12
    Member
    Join Date
    Oct 2011
    Posts
    54
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    8
    I have discovered that a "blown-up" part with no sign of smoke damage will help indicate the possible cause. In my case, a transistor had "blown-up" with no sign of smoke damage. This indicated the transistor may have been damaged from a very quick onset of high current (without time to smoke). The only other component in the circuit that could quickly cause high current flow was another transistor. The suspect transistor was tested and it was shorted. On the other hand, if the "blown-up" transistor showed any sign of smoke damage, I may look at other components that would cause a slower onset of high current.

    This may not seem like a big deal to some of the experienced techs, but if I can save time on a repair, I will use every learned experience possible.

    0 Not allowed! Not allowed!

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. "Blows Fuses" and "Is my transformer dead?"
    By R.G. in forum Maintenance, Troubleshooting & Repair
    Replies: 23
    Last Post: 09-14-2012, 03:03 AM
  2. irritating "sheen" on "A" notes
    By deci belle in forum Maintenance, Troubleshooting & Repair
    Replies: 27
    Last Post: 09-12-2012, 01:34 AM
  3. Replies: 3
    Last Post: 06-22-2011, 03:58 PM
  4. Replies: 9
    Last Post: 02-24-2011, 03:21 AM
  5. Peavey Delta Blues - No Sound - All Tubes Glow - Powered "On", Made a "Hum", and died
    By Renegade44 in forum Maintenance, Troubleshooting & Repair
    Replies: 15
    Last Post: 12-15-2009, 05:24 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •