Replacing 12vdc power supply in Sauna Control Box

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Old 11-28-18, 05:07 PM
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Replacing 12vdc power supply in Sauna Control Box

Greetings

I did a little searching here but didn't see this issue specifically, so I hope it's ok to ask in a new thread. I have a faulty 12v dc power supply in the control box for my older (2005ish) dry infrared sauna (heat sink was getting current and arcing on the chassis). It is a model number 0757-83835018. May be similar to a board used in wine coolers apparently...

I think it was driving my color-changing led lights and cd player. As the sauna company is out of business, a replacement pcb is unavailable, but I think it's a 12vdc 6a power supply. In another forum it was recommended to replace it with something like this:
https://www.amazon.com/dp/B007C7DWL8?tag=fixyaconvert-20
looks like this has up to 12.5a output, yes? The fact that my old one is 6a just means it won't use the whole capacity right?

With the chassis size of a power supply like that, however, I'd have to mount it outside of my sauna control box chassis.

a.)is something like this a viable solution to feed the main pcb (with relays on it etc) which is currently getting a 12v+ and ground from the existing power supply, and b.) if so, what might be a good solution to run this outside of an existing sauna control box chassis?

Also, I'm not sure but do my main sauna heater relays interact with this 12vdc in any way? Do I need to worry about compatibility there? (I also need to replace some relays as well, but that's something I'll ask about later). My relays are similar to these I believe (see attached image as well):
http://www.kysanelectronics.com/graphics/1411053.pdf

The sauna itself uses 4 ceramic heaters, each 120v 163w

Photos attached
 
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Last edited by nbarr7; 11-28-18 at 07:12 PM. Reason: added photos
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Old 11-28-18, 05:15 PM
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Was going to post photos here, but found out how to attach them to the above post instead...
 

Last edited by nbarr7; 11-28-18 at 07:12 PM.
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Old 11-28-18, 10:07 PM
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Welcome to the forums.

Yeah..... those old Hanny boards were used in many things...... mostly Peltier fridges and wine coolers which is why you see them mentioned. They cooling module required 70 watts and that powered it. I can't understand why they never came out with a direct replacement for it. A 100w semi direct replacement is listed in the link.
XP - the big guys in switching supplies
XP power supply -retail

However...... the supply you linked to will also work fine. Much larger than you need but much more economical. It will require some creative hook up. Yes..... that board does use the 12vdc for control. Those relays are 12vdc.
 
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Old 11-29-18, 06:55 AM
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Thanks for the reply Pete. I thought the relays were 12vdc. Thanks for confirming. As for the power supply, even with the extra size, admittedly $10 is easier to stomach than $75 (though your replacement link looks perfect). Does the 6a original output vs the 8.3a in your link or the 12.5a output in the amazon module mismatch matter much?
I hate to just go the cheap route out of hand, but I could replace the cheaper power supply 5-6 times if needed before reaching the cost of the other one. I suppose to use the larger power supply I'd have to drill through the chassis, run new power wires and heat shrink any solder joints etc. This whole control box just sits on the sauna roof, so it's not like I'm lacking for space - just want to make sure everything is safe.
 
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Old 11-29-18, 07:08 AM
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If any of the load circuits (12V) are accessible in normal use; I would pick a power supply with decent safety ratings (CL2). Is one of the 12V load connection earthed? IF not, it is a huge "trust me" with that unknown PS vendor that keeps mains off of the 12V side.
Especially in a sauna situation.
 
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Old 11-29-18, 06:04 PM
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Thanks for the advice, though is anyone able to clarify this advice in slightly more basic terms? I am admittedly not an electrician, so I am less familiar with some of the terminology/concepts. I will do my best.

Also, I don't have a schematic for the sauna, I'm just going off what I can see topside of the boards.
 
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Old 11-29-18, 06:54 PM
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If you have an ohmmeter. Unplug the DC cord from the main board. Check from the negative pin on the main board to the metal chassis. That will tell you if the negative is earthed.

A switching power supply takes the 120vac in..... converts it to DC and then runs it thru a switching circuit (transformer). Based on the quality of the board or even more important is the quality of the switching transformer..... you can end up with the 120vac line showing up on the + or - of the 12vdc output. If the control circuit is not grounded..... there could be a 120vac shock potential. The better power supply companies build in more isolation in their power supplies and use much better transformers to eliminate any leakage.

The one you linked to may be fine but it doesn't offer any isolation documentation or certification of safety..... especially to be used in what could be considered a wet environment.
 
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Old 11-30-18, 06:47 AM
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Thanks for the clarification. That I can generally understand. There is a 12v transformer in the chassis itself, though admittedly I don't know it's relation to the power supply. And just to reiterate, this is a totally dry sauna. It's an infrared so no steam, no water, no moisture at all.
 
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Old 11-30-18, 06:51 AM
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https://www.digikey.com/products/en/...=1&pageSize=25

Branded, not deadly, and speced for what you need. Still Asian sourced, so costs are reasonable. Amazon is a minefield for this type of thing; Many low end players in the "LED" driver arena. Most all junk.

TDK, Meanwell, CUI, XP power are good names to look for. DK has quick links to the data pages. Look for 3 or 4kV IN/OUT isolation ratings.

Also, It is not obvious to me what is drawing so much power on this control box.
 
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Old 11-30-18, 07:32 AM
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Thanks for the link - I just have to search my needed power requirements and I'm in business eh? Even something like that first TDK should be usable with a 6a output, no?

The only other thing that this 12v power supply is likely driving which is not reflected inside the control box is there is an automotive type stereo, and a module for the color changing LED lighting system that are both external to the control box.
 
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Old 11-30-18, 07:51 AM
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If it fits mechanically, the TDK should be fine. Ah, 12V stereo. I suspect that is responsible for some 75% of the entire current draw.
 
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Old 12-01-18, 02:33 PM
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Yes I actually don't know what the current draw would be, but I'd imagine the stereo is the most yes. The relays can't be too much.

I suppose DigiKey would have a relay replacement for me also eh?
 
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Old 12-01-18, 02:41 PM
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If DigiKey doesn't..... Mouser will.

The car stereo will use 2-3A depending on the volume.
 
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