Transistor Heat Problem Stumper

Discussion in 'General Electronics Chat' started by joe_mahma, Oct 19, 2009.

  1. joe_mahma

    Thread Starter New Member

    Oct 19, 2009
    For you smarter kids in the class, please tell me if it's OK to substitute a Tip 142 of smaller size (pins are narrower, etc.) for the original in a low frequency amplifier bass shaker circuit. I'm replacing the original because it seems to have shorted out and fried a small resistor as well as taking out a 2n5551 and a 2n5401. I only know about the transistor shorting thing because a tech at the company suggested it. about I use some Arctic Silver thermal grease on that new little sucker (it's attached to a BIG aluminum heat sink)? I'm not sure of the package size of the replacement (218 maybe), but I'M NOT SMART ENOUGH to figure out these questions. It goes without saying that I'll be very grateful for any help you folk can send my way.
  2. SgtWookie


    Jul 17, 2007
    What is the part number of the transistor that you are replacing?

    There should be several other transistors attached to that large heat sink.

    It would be very helpful if you could post a photo or draw a sketch of the transistor locations on the heatsink, indicating their part numbers, and where the blown transistor was.

    Amplifiers usually have symmetrical outputs. It won't be too hard to figure out what's missing.
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
    If you post the package types of the old and new device, I can tell you the difference in thermal resistance from junction to heatsink.