Heads up, the powder coat oven is down.
Looks like the solid state relay has cooked itself again…
I have a spare beefier relay that we’ll try to put back in it in the next couple of days.
With Gretchen and James’s help last night we were able to diagnose the problem.
The solid state relay had decided to release it’s blue smoke in spectacular fashion and somewhat fortunately, failed in the off position.
Even though the relay was rated for double the anticipated load, I think it failed due to the amount of use it was seeing (some electrical devices have a duty cycle, so while they can handle a rated load, that does not necessarily mean it will function forever at that rated load)
…fortunately, after not trusting Amazon electronics, and not wanting to walk into a sauna again, I had a beefier MGD relay on hand that should handle a higher load and also has a rated duty cycle.
I have not run the oven up to full temp, but it did heat up to 90c before shutting it off during my lunch break.
I am very thankful a member reported the issue immediately. By reporting the issue, we were able to keep the down time to a minimum.
6 Likes
How much does the oven heat up the control box? If the oven is heating the heatsink that the relay is mounted to it probably won’t do a very good job of keeping the relay cool. I can’t tell if there is any insulation there, but it might help to add some separation and/or active cooling. Power electronics will be de-rated significantly if they are not properly cooled.
3 Likes
I’m gonna say that the insulation is pretty much non-existent between the electronics box and the oven… moving the heat sink to the bottom of the box may have been on my to do list still from last time, but adding a fan should be pretty easy since I think that display panel runs off of 12v… and that may have also shortened the other’s effective duty cycle as well…
This is definitely the 3rd or 4th time that relay has been replaced.
3 Likes
Came here with the same Question as quristian. From that one pic it should be easy to add a 12v fan. There might be some spare ones in the electronics lab. Probably over where the transformers and motors are. I try to keep all the electromechanical machines together
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On Wed, Mar 22, 2023, 13:33 Rustin Atkeisson via MakeICT Forum <noreply@talk.makeict.org> wrote:
| rustin.atkeisson MakeICT President & Metal Committee Lead
March 22 |
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I’m gonna say that the insulation is pretty much non-existent between the electronics box and the oven… moving the heat sink to the bottom of the box may have been on my to do list still from last time, but adding a fan should be pretty easy since I think that display panel runs off of 12v… and that may have also shortened the other’s effective duty cycle as well…
This is definitely the 3rd or 4th time that relay has been replaced.
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In Reply To
| Christian MakeICT Member
March 22 |
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How much does the oven heat up the control box? If the oven is heating the heatsink that the relay is mounted to it probably won’t do a very good job of keeping the relay cool. I can’t tell if there is any insulation there, but it might help to add some separation and/or active cooling. Power electr…
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3 Likes
Is the control box a box or just a 4 sided shell? Better than just separating the SSR and heat sink from the oven would be too enclose the controls and put some space between the control box and the oven itself. A gap and a sheet of stainless (poor conductor, good heat shield) will help a lot. Adding a fan to the control box forcing room temp air across the heat sink would be a good idea.
4 Likes
I have several these airline hot boxes the insulation inside of them is only an inch of fiberglass. I have one torn apart to repair currently. I completely agree with making a stand off and I would put in the fan.
2 Likes
The easy bake oven is down again…
From what Joe and I can tell, the thermistor has somehow gone bad according to the display (it shouldn’t show the ambient temperature if. The solid state relay (SSR) looks like it’s fine this time, but since the controller is getting a weak signal from the thermocouple, the controller is pretty much telling the SSR to run wide open continuously.
I’ve ordered an identical kit from Amazon that should be here Thursday.
I’m definitely thinking of putting more of an air gap between the controller box and oven in the near future as well as make some other more robust changes…
1 Like