[scirocco70]

Hey everyone...

I have the above primary control on the Beckett AFII 85 burner on my furnace. It appears to be bad... there is 120V supply to it, and it will buzz when the furnace is on, but after a few seconds it pops the red button.

The oil-burner fan/pump motor never runs, and I started there and removed the motor and bench-tested it, as well as cleaning the heck out of the oil pump (it's an A2VA-7116), which really needed it anyhow. My annual service guy cleans the big filter, but I've never seen him touch the pump.

Anyhow, all of this seems to be fine, so I put a meter on the ORANGE wire coming out of the Honeywell control, which I believe should show 120V to start the burner motor and ignition transformer. There is no voltage there.

The relay inside moves, clicks and looks fine. I see no obvious issues (burnt spots etc) anywhere on the board.

It appears this exact part is not used anymore, and indeed I'm not sure I really need a 40VA transformer on this thing (gets warm all the time, uses a lot of power?)

What is the best/correct modern replacement?

Thanks!
~aaron

References:
http://www.beckettcorp.com/protect/t...II%20R0803.pdf

PartsGuy.com -- Search results

[juggallojed]

That seems to be a good part number still , make sure your getting 24 volts to the control, as lower voltages will cause the relays to chatter and fail.

[scirocco70]

Thanks for the help!

The relay isn't chattering, and the 24v seems to be all good.

In fact, I've discovered the problem... I took it all apart (nothing to lose) and found a burnt solder connection on the back (underside) of the circuit board.

I got to this point by poking around with a meter... it gets a good 120v on the black (hot) wire, and 0v on the orange (output to blower) wire. So, going back to where the wire comes out of the circuit board, still zero.

On the hot side of the relay (the contacts of which are clean and make firm contact), it has 120v.

Flip the board over, and the pin from the hot side of the relay is burnt. See the photo.

I am going to resolder this joint, which is easy enough. But I do wonder what caused this to happen... this furnace was installed in 1996, and this part has presumably never been replaced.

What could cause this to happen at this point? Serious over-current?

The high-pressure pump was pretty gunked up (seriously slimy screen, needed a dip in a carb-cleaner bucket even after being disassembled), and caused some noticeable drag on the fan/motor before I cleaned it. After cleaning, on the bench wired direct to 120v, it spins like a top, no vibration or noise.


So maybe the drag caused the 1/7hp blower motor to lock up, which caused a serious current draw (44 amps according to the label on the control) which burnt the solder?

We'll see if it all works when I get it back together in a few minutes...


Thanks again!