Convotherm 4 Combustion Blower Problem

[fixbear]

I can’t tell from thee pictures what kind of component you have failing due to shadows. But two things i’d be looking at are cooling/ventilation of the board, and how clean and stable is the incoming power. Electronics do not like surges or heat.

[techtownmayor]

Looks like an SMD resistor, and like fixbear said,heat and surges are the enemies, though in this case, it looks more like a catastrophic failure than a long-term heat damage.

[olivero]

Good to know, so I’ll be looking for that when I go to replace it.

Checking incoming voltage and if there’s any heat sources that are unnescessary.

Thank you.

[fixbear]

Air cooling of the board.

What’s with the high trace heat on the back from the electrolytic capacitor. One third of the way around from the hall effect speed sensor. Is this a three phase machine?

[fixbear]

Don’t let the heat from the ceramic wire wound resistor bother you. They make heat when they are working. That’s why they are ceramic. But the air-flow over the board to cool the power transistors and resistors is very important. As well as cabinet temp. I know you have had some combustion leaks in the past. They can deposit a conductive film on the board that will cause problems down the road.

[fixbear]

I have to apologize. I finally found a way to blow up the DSC2060 photo. I thought you were referring to the white porcelain resistor next to the destroyed item. I’m not sure that that one is a resistor, It may be a surface mount Mylar capacitor. Snap a pic of the new one and give us the numbers off it. If it is in fact a cap, moisture and your flue gas leak will be the problem. Because it’s open wrapped, Any conductivity between the layers around the edges will short it. Damn I wish I could be there. I have a surface mount soldering, de-soldering station. This looks like a fun project to me.

[techtownmayor]

Your knowledge and experience never fail to amaze me. Plus, I’m jealous that you have an SMD rework station at your disposal 🙂

[fixbear]

Tenna 21-10130. Had to change a charge plug on a special laptop that got dropped. SMT has ruined it for most. Electronic supply companies have died in my area and the big on-line houses have mostly been taken over and combined into one. Very sad to me.

I started at 7 with a crystal radio receiver. Mid life I got into Large Scale RC. Built my own transmitter and receiver from a Ace kit. Lots of delicate work using a magnifier on the receiver board. But one learns a lot with hand on. Had to take it half way across the state to a tech to get the FCC certification before I could license and use it.

[fixbear]

On a side note to Olivero’s problem. If your cleaning system had a leak and acidic fumes got to the cap, they will make a very conductive path with humidity.

[olivero]

<div>Would there be any benefit in replacing the entire fan assembly or should I just replace the board?</div>

[fixbear]

The only way to tell that is to check the bearings and megga the windings. Since I’m not in FL, I can advise on that. Also availability comes into play.

[olivero]

Well, Fixbear, I ended up just replacing the whole thing to be safe, turns out it gets power directly from the main control board AND it turns out there’s a fuse on that board for each fan, which it doesen’t show on the diagram, a slow blow (or Ceramic, I’m assuming it’s slow) 2A fuse which was blown.

I wonder if the old board still worked, but I doubt it, probably blew that board and then the fuse died as well.

Power was 230V on the dot, so not much trouble with that, draws 0.7 Amps at full bore in service mode, so I don’t know why they use 2A, seems a bit high. I put in a 1.6A fast acting fuse instead, feel safer with that.

Rather it blows a fuse then the board, about a $999 price difference between the 2.