faulty electrics in Infrared Sauna as it's not turning on


Postby nigeldunkley » Sat Mar 04, 2017 12:24 pm

Hello

I purchased this sauna used a couple days ago, and its not turning on..

The previous owner sold it as having only an issue with the fuse, but I have exchanged all fuses, and Im assuming its one of the three components that are running in the rectangular unit mounted on top of the sauna.

I will post all the photos so you are able to see detailed views of everything - I have now ordered a replacement for the power supply (s-35-12) as I cant imagine the transformer would short the entire sauna. internal fuses are all 3 amp, this is the power supply (but the power running from mains is standard 13amp):

https://www.aliexpress.com/store/produc ... 13295.html

And from what I can tell there is a sort of voltage regulator on that PSU which has a phillips white screw which is used for adjusting. My guess is that previous owner set it for wrong output and it blew the PSU?

Alternatively there is the main board, but I wouldnt know what to look for, nor how to replace, as it had no particular model number.

I tested current coming from mains to the main board (sorry I dont have technical name for that) and electricity is definitely arriving there, but not sure where (or if) it goes after. I tried to swap one of the kettle lead fuses for the one on the PSU board, and then power on, but as soon as I tripped the power to on it blew the fuse..

Thank you for your help!
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Postby nigeldunkley » Sat Mar 04, 2017 3:58 pm

running more tests with new fuses, when all fuses are replaced and new, the one that continuously blows when I plug in is circled in light blue.
When that blew the last time it shattered the fuse and the piece circled in green sparked and a piece flew off the top of it, like a chip (see below)
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Postby ericmark » Sun Mar 05, 2017 5:43 pm

It looks like a switched mode power supply, basic idea is the AC is turned to DC a capacitor charged then it's turned into high frequency AC so the transformer can be a lot smaller, if anything makes it so you don't get high frequency AC then the transformer becomes a dead short.
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Postby ericmark » Sun Mar 05, 2017 6:01 pm

Sorry called away, in real terms it is very hard to repair a switched mode power supply, some times you can see an exploded capacitor, but 9 times out of 10 it's a case of renewing the whole unit.
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Postby nigeldunkley » Mon Mar 06, 2017 5:45 am

Thank you - I have now purchased a new unit which will arrive today and I will replace. Would you say that the symptoms are definitely those of a faulty PS, and not a fault in the circuit board as well?

I was also reccomended to swap the fuse that is blowing for a 5 or 10 amp slow blow - would you agree?

Thanks again
Nigel

ericmark wrote:Sorry called away, in real terms it is very hard to repair a switched mode power supply, some times you can see an exploded capacitor, but 9 times out of 10 it's a case of renewing the whole unit.
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Postby ericmark » Mon Mar 06, 2017 1:23 pm

I have found reverse engineering hard, and I would not try to work out what a circuit board does without having it in my hands.

Fuse likely went for a reason, that reason could be old age, but without knowing what it does I would not put a larger one in. If you know what the fuse does then you can work out yourself what size it should be.

I remember a bottle fuse blowing on a freezer, it went twice so then I started to look why, the freezer motor was rated larger than the fuse, but a 25A would not fit the holder,as a stop gap I carefully removed the foil in the 25A and put it in a 16A and refilled with sand. I was scratching my head as how the originally 16A held, on the return of the regular camp electrician I asked him, seems he had done the same as me, as he had no 25A bases. But this is unusual only once has it happened to me. So I would say keep the original fuse size.

I don't know why the unit needs all the control panels, it may be some safety feature to limit your exposure, in general repairing some thing which has broken is OK, but buying something broken to repair it is a bit dodgy, OK buying it for spares, but unless you know what it should do, then you will not be alerted if there is a fault.
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Postby nigeldunkley » Mon Mar 06, 2017 1:27 pm

Thank you! I replaced PSU, and swapped fuse from 3amp to slow blow 10, and its working great!


ericmark wrote:Sorry called away, in real terms it is very hard to repair a switched mode power supply, some times you can see an exploded capacitor, but 9 times out of 10 it's a case of renewing the whole unit.
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