OT - Troubleshoot Oil Furnace UPDATE

Did not get right back to this from about a week ago, but thanks for the help.

Went down to the furnace and opened the junction box to follow power around and see if I could get it going myself. Found this circuit board. Could see voltage as stat called for heat and fan energized after appropriate time delay and stopped after heat signal was not present...so stat and fan are working as advertised.

Jumpered the T-T terminals on the burner and could force it to fire...so burner is working also.

That leaves this board so I call my friendly Trane service guy and he agrees to check price and availability for the board. Trane wants $320 for a $5 board. Go back down to the basement and get a Honeywell part number off the board and call local supply house and they have it on the shelf and it will only set me back $80.

Thought about "reverse engineering" the board since I had it narrowed down to either the stat relay that signals the burner or the limit control and going to Radio Shack for components and exercising the soldering iron. Wife just wanted heat though so I figured I was saving $240 on parts and whatever a service call might have been.

Replaced board and everything functions properly again.

Anyway, I appreciate the help from this board.

I would review the back side of that board for bad solder joints. pay special attention to the ones for the relays. You just might be able to get a working spare out of it.

Glad to see you have it working again.

I did turn it over and did not see anything that looks bad at all. You can kind of see some corrosion at some resisters towards the lower right of the board, but not sure that was any of the trouble. I will not throw it away. If I have another issue I might be able to get a working board between the two I have now. Of course that might be a few years from now and I will not be able to find the board then.

Kirk

Probably one of those discrete IC's that can only be purchased if you are an OEM.