I have an RV with a failed propane water heater. I did some investigation and found that there is a small circuit board called the "Gas Ignition Control Module". The unit is Suburban MFG #35-525900-113. When I was checking this in the RV, I was getting a "burnt electronics" small and I noticed that the cover of the board was hot to the touch. I searched some RV forums and found a number of posts that confirm a failed Q3 transistor on this board, which results in exactly the issues I am seeing.

These two photos show the Q3 transistor between the yellow relay and the black round thing. The solder points are the three in a row, like Orion's belt.

Front of Board

Back of Board

This is a simple one-layer board and it would not be much of a challenge to solder in a new transistor - but how do I know what transistor is needed for the application?

 

If you look very closely at the flat side of the transistor, there will be numbers etched there that help identify it.

Once identified, you can source a replacement, or equivalent.

 

To avoid to lose the images, please upload the image files to the forum next time, thank you.

 

Thank you. My eyes are not that good - I would pull the component of and look at it with a magnifying glass, but I found an answer on another forum - it's an MPSA29 and I've got some on order. Now I know where to look if this happens again.

 

It would appear as if someone had this problem before and the transistor was replaced.

 

It seems this is a very common failure, along with the power resistor to it's right. You might be wise to replace the MPSA29 (only 600mW) with a higher powered darlington, or at least clip a small heat fin to the MPSA29.

 

Thank you. My eyes are not that good - I would pull the component of and look at it with a magnifying glass, but I found an answer on another forum - it's an MPSA29 and I've got some on order. Now I know where to look if this happens again.

Can you take a full picture of the track side, I'm just wondering why there is another transformer?