# Help finding a M0265516 transistor

#### Michael Efanow

Joined Apr 4, 2016
14
Transistor substitution

Hi guys, I'll try to keep it brief and clear, I'm after a M0265516 in TO220 package. Or a suitable substitute. It's from the variable speed on my Bosch cordless drill that's about 12 years of age, the variable speed unexpectedly stopped working for no obvious reason. How you can help. Thanks Michael

#### Attachments

• 933.3 KB Views: 15

#### hp1729

Joined Nov 23, 2015
2,304
Best I can tell it is an SCR.I can find them listed for sale for about $1.65 but "no longer in stock". Try most any SCR in a TO-220 case. What do you have to lose? It already doesn't work. #### SLK001 Joined Nov 29, 2011 1,543 I seriously doubt that it is an SCR for a DC variable speed controller. Probably, it is a house marked power transistor. Good pictures of the top and bottom of the speed controller will help in finding a substitute device. #### hp1729 Joined Nov 23, 2015 2,304 I seriously doubt that it is an SCR for a DC variable speed controller. Probably, it is a house marked power transistor. Good pictures of the top and bottom of the speed controller will help in finding a substitute device. Not bad reasoning. I find it listed under Thyristors but can't see it being a triac. So what damage can be done by plugging in an NPN, PNP or SCR? #### SLK001 Joined Nov 29, 2011 1,543 Not bad reasoning. I find it listed under Thyristors but can't see it being a triac. So what damage can be done by plugging in an NPN, PNP or SCR? I would want to see a schematic, or at least the requested photos. Perhaps it is part of a PWM output and the OP can see a pulse train going into the device. Thread Starter #### Michael Efanow Joined Apr 4, 2016 14 I'll get the requested photos in a few hours guys. I've got a few scrs lying around from a touch lamp fix. Thread Starter #### Michael Efanow Joined Apr 4, 2016 14 Here's some images. Today I've rang some local electronic component specialists. One tried to find the specs on the M0265516 but to no avail. #### Attachments • 307.8 KB Views: 12 • 226.7 KB Views: 11 • 299.1 KB Views: 15 #### SLK001 Joined Nov 29, 2011 1,543 Remove the device and test it to see if it is really bad. A lot of times, it is the printed potentiometer that is the problem. What is the number on the SOIC-8 part on the board? #### Dodgydave Joined Jun 22, 2012 8,674 Thread Starter #### Michael Efanow Joined Apr 4, 2016 14 Any idea how I can get a data sheet on the m0265516? Thread Starter #### Michael Efanow Joined Apr 4, 2016 14 Remove the device and test it to see if it is really bad. A lot of times, it is the printed potentiometer that is the problem. What is the number on the SOIC-8 part on the board? Which part has that number on it, I can't see it? Thread Starter #### Michael Efanow Joined Apr 4, 2016 14 Remove the device and test it to see if it is really bad. A lot of times, it is the printed potentiometer that is the problem. What is the number on the SOIC-8 part on the board? How do I test it without a data sheet? Thread Starter #### Michael Efanow Joined Apr 4, 2016 14 How can I test the printed pot? The drill used to only run at full speed with near %100 trigger, it used to run slow from say %5 trigger and increase with more trigger. What's happening now is its running at full speed with %5 trigger and through to %100 trigger. #### SLK001 Joined Nov 29, 2011 1,543 #### Attachments • 751.8 KB Views: 6 #### SLK001 Joined Nov 29, 2011 1,543 How can I test the printed pot? The drill used to only run at full speed with near %100 trigger, it used to run slow from say %5 trigger and increase with more trigger. What's happening now is its running at full speed with %5 trigger and through to %100 trigger. If your drill is running at any speed, then there is nothing wrong with your transistor. Clean off the grease from the linear pot area and see if there are resistance variation from one end to the other. There is a lot of carbon in the grease that has sluffed off the pot - possibly too much to make the control salvageable. #### Lestraveled Joined May 19, 2014 1,946 If your drill is running at any speed, then there is nothing wrong with your transistor....... Wrong. Look at the 3rd picture in post #7. There is a bypass switch for maximum torque when the trigger is pulled all the way in. #### Lestraveled Joined May 19, 2014 1,946 The Mosfet (huf75339) is$1.70 each at Digi-key. Also just as a test, almost any N chan Mosfet would work.

My advise, spend a couple bucks and replace the Mosfet. If that doesn't fix it you can replace the trigger module (PN 2607200421, \$46.24) or pitch the whole thing.