Suburban #HF50B Circuit Board

[Southern]

My sister has a Suburban furnace and the fan motor kept running with no heat. She was told that there were no replacement parts available for the furnace and the only option was to replace the entire unit with a more conventional style furnace. This would require re-work of the duct work and She was quoted $7000.

I got the circuit board and there are some burnt traces on the edge connectors. I can try to repair the edge connectors but I feel that what ever caused them to burn in the first place is still the problem.

The circuit board has HEC Carborundum 114-500-3022 silk screened on the board.

Any info would be appreciated.

[jumptrout]

Could just be age that caused it to break down.

If the heat exchanger in the furnace is good,try a repair on the board.

[Southern]

It doesn't appear to be age related, the rest of the circuit board is in great shape (no yellowing or burn marks). Two of the edge connectors that fried was a jumper, the trace didn't go thru the circuitry, the third edge connector that is damaged was adjecent to the jumper traces. I suspect that what ever is connected to the other side of the jumper malfunctioned causing the edge connector to "melt".

I will try a repair on the board since I have nothing to lose.

If someone has a schematic for the Suburban furnace that would help me.

[jb8103]

I'd never heard of Suburban. Google search says they're RV furnace manufacturers.

http://www.rvcomfort.com/suburban/about.php

Where's this thing installed?

Anyway, $7000 sounds, how shall we say, just a tad on the high side.

[Southern]

The builder of the Condo my sister lives in used an RV type of HVAC unit since it was installed in a small space near the ceiling. The $7000 included a new regular sized HVAC unit and reworking the duct work. Apparently there aren't many contactors willing to due this work since it is dirty messy job to tackle.

I did some checking of the circuit board and there is a small transformer that has the primary windings shorted. Without a schematic it would be a crapshoot to attempt a repair.

I have contacted ICM controls to see if they offer a replacement circuit board, I sent them photos of the board showing the manufacture and model number.

[jb8103]

Or maybe go through a local RV dealer. Things are quiet for them right now, they might actually help you out.

[Daveb1972]

Honeywell makes a pretty good universal integrated furnace control, part number is S9200u, and is made to control HSI induced draft furnaces, and include blower control. If you send me a picture of the control, and all of the numbers visible on it, I can see if there is a direct crossover to this or another control. I have used this control in several applications. The existing control may have been the victim of water contamination causing the short, or often they will blow out a relay terminal. post detailed pictures, and I can help further. Include pics of the furnace and I'll see what I can do about better schematics. I would avoid "fixing" boards because of the nature of the electronics, and the need for the timing logic to operate correctly for safety. An example is if the unit fails again, but fails to open the gas valve circuit, the unit will run burner, without blower, and cause a fire, same if the control keeps gas on, if it fails to light, boom....I have seen modules do this, so NO MODIFICATIONS TO THE BOARD should be attempted. Not worth the risk. The universal boards often will satisfactorly replace a hard to find board, and if installed properly, they are safe, and the liability is then on the board manufacturer.

[Southern]

Below are photos of the circuit board:

I will ask my sister if she can take some photos of the furnace.

Any assistance is appreciated.