Daughter's Swing

[nutech]

Hey there. My daughter's baby swing stopped swinging today. The swinging circuit burned out. I'm pretty sure I know which components need to be replaced, just would like a second opinion. Thank You.

 

[chemelec]

Yes that Part for Sure.
Was it Laying on the PCB or Standing Upright as shown?
And did it Damage the PCB?

Would be a Good Idea to put a Heatsink on the New Part.

 

[AnalogKid]

That is a 3 amp, 60 volt PNP power transistor by On Semiconductor (owners of a lot of Motorola's discrete designs).

https://www.onsemi.com/pub_link/Collateral/MJE171-D.PDF

ak

 

[atferrari]

The PCB suffered as well. Why?

 

[dougy83]

The PCB suffered as well. Why?

Due to chronic heating from the transistor

 

[JimB]

There is a chance that the overheated transistor may be OK and that the real problem is that one of the solder joints on the circuit board has gone open circuit.
If that is the case, cleaning the old solder off the joints and re-soldering is all that is needed to make it work again.

Whether the solder is bad or the transistor is bad, once it is fixed the transistor needs a heatsink.

JimB

 

[nutech]

Yes that Part for Sure.
Was it Laying on the PCB or Standing Upright as shown?
And did it Damage the PCB?

Would be a Good Idea to put a Heatsink on the New Part.

It was laying flat as you could see in the pics it burned the board but I think I'll replace it and the cap.

 

[Jugurtha]

It's a TO-225 package with no metal plate. Here are some resources for your heatsink:

Calculating heatsinks
Mounting Considerations For Power Semiconductors - On Semiconductor

 

[nutech]

Thanks a lot guys. I was digging around in some of my old boards but I couldn't find anything. I'm a copy machine, and printer technician, so I have an absolutely amazing selection of parts off boards, clutches, solenoids, servo moters, ccd's lasers, all kinds of stuff. Maybe we can help eachother out once in a while

 

[Tony Stewart]

Also check the swing switch. this is used to commutate and momentarily drive the motor.
If there is contact bounce, the normally cool transistor may oscillate and overheat and cause arc burns on contacts.
Stalled motor may also overstress the transistor.

 

[audioguru]

Stalled motor may also overstress the transistor.

Yes, I suspect the motor jammed or ran out of oil then the poor transistor was driving almost a short circuit.
Maybe the missing Q1 was a current limiter.