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What Might Be The Cause Of Transistor Heating?

By on May 27, 2013

From experience I could only think of six reasons why a transistor could get hot and eventually burn. Here are the reasons:

1) The quality of the components- If it is not original then it could cause heating problem

2) Heat compound dried up- Yes, sometimes when an equipment in service for a long time, the heat compound could get dry and this will cause the transfer of the heat from the transistor to the heatsink not to be so efficient. A new transistor with   fresh heat compound will usually solve the problem.

3) Leakage- Although this is not so frequent, it did happened few times. The transistor back body had tiny leakage causing minor arc to the heatsink. The transistor could get hot and eventually burn.

4) Bad corresponding components- This is very true especially if there is a component (usually capacitor and resistor) have problem causing the transistor to get hot and burn. One must always check corresponding components before replacing with a new transistor and turn it on.

5) Spilled liquid- Make sure the surrounding area of the transistor is clean and do not have any spilled liquid like coffee or cola.

6) A slightly higher voltage- If the transistor works on a slightly higher voltage than the transistor can handle, then it will slowly gets hot and have problem. Let’s take the horizontal output transistor (HOT) as an example. If the B+ supply voltage is higher than the normal chances the HOT will run hot and get shorted.

If you take in the consideration of the 6 tips that I have listed above then chances is very high the replacing transistor will not get hot again and burn.

If you have other tips then the above please leave a comment below and I’m very sure many of the readers would like to know about it-thanks.



  1. Gopal Sharma

    May 30, 2013 at 3:01 pm

    In my view, if base voltage is not sufficient to HOT, it will heat and may be burnt out after few minutes.

    • Jestine Yong

      May 30, 2013 at 4:31 pm

      Hi Gopal,

      Yes if the base signal is improper the HOT will get hot and burnt.


  2. Anebi electronic

    September 21, 2018 at 9:24 pm

    Two important reasons why a transistor will quickly heat up and get short-circuit(burn out).
    1. If the supply voltage to the transistor base is higher than the rating voltage of the base transistor. The transistor will quickly heat up and burnt.
    2. If the current supplied to collector-emitter terminal is more than the transistor collector-emitter current, then it will definitely heat up and get burnt.


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