Cooking STC-1000

[wildburkey]

Has anyone ever had a problem with an STC1000 heating up? I scored a free fridge the other day and traced the fault back to the thermostat. I ripped the old thermostat and light out and wired the stc power from the neutral power for the light (blue in picture) and active to the starter (and light) from the old thermostat, I then jumped the active over to the relay switch (7) and placed the white wire (which the old thermostat made contact with the active to start the compressor) in the other side of the switch (8). When I turned it on the STC started heating up so I assumed it must be shorting/ conflicting with something in the fridge circuit somehow. I couldn't figure out why this would happen because the old circuit with the light in would have been wired the same e.g. the light was powered off the same active wire from the thermostat/ starter and the neutral I am powering the STC off. This morning I wired the STC up on it's own power source and it still does the same thing with just active and neutral connected to 1 & 2. So now I'm not sure if I buggerd it with my initial wiring or if it's just a faulty STC. I have put the multi meter over the STC terminals and nothing seems to be shorting between 1,2,7,8. The unit heats with just the power plugged in and nothing else wired. It would be Ideal if I can wire it as planned cause then I would be able to mount the STC in the door and have a heat pad, the stc, and fridge all running from the one power source in a nice tidy fashion. Here is a pic of the wiring in the fridge - the brown and white are active (they contact the starter for the compressor) the blue neutral and the earth wire is to the old thermostat. Any ideas what the problem is here - I personally think it is must be a faulty STC unit.
EDIT: Not too sure if anyone can make any sense of this, just wondering if anyone has wired a STC this way before. I might just have to run in a project box the usual way.

 

[rude]

Mate without trying to decipher what you have posted a diagram would be easier

Don't know why you took the thermostat & light out no need just turn thermostat all the way

Just re-read you have faulty thermostat ? Just connect active to switch wire bypass thermo

Just sit stc on top of fridge with power from lead going in

Fridge plugs into another lead coming out of stc for cooling

Winter time you will need another wire for heating

Run sensor wire in between door seal & tape to fermenter

I've done the same for my heating cable going to a 50w cubicle heater

I have 3 stc 1000 & all good are you a sparky ?

 

[wildburkey]

Update: it must be the stc unit, I just rigged up another single relay temp controller in the same fashion and it worked fine . I Just ordered another STC seeing as I want to also control a heat mat to use the fridge for fermenting.

 

[wildburkey]

Cheers beer god, I'm not a sparky but have the general know how. I have made temp controllers, power controllers, wired elements and built my own tube amp; I test then stand back when I fire em up then get my sparky mate to check em over, lol.

 

[rude]

All good mate no wires going under the door seal for you

 

[dblunn]

Maybe a silly question but it was a 240V STC wasn't it. Not a 12V version.

 

[wildburkey]

When I researched this there was one major con in bypassing the thermostat - if the controller should fail to switch off your brew can freeze. I have never had an issue with one failing to switch however. This is a much more simple installation IMO and could be hooked up the same with a working thermostat.

 

[wildburkey]

Yep 220v, not a stupid question at all m8, cheers

 

[TheWiggman]

What you have there isn't an STC-1000 per se, it's a copy that only heats or cools. I'm not sure if they're 'inferior' but I'd wager they'd all come from the same continent.
I've never checked to see if mine heated up because it's locked away safely in an electrical enclosure. Does it heat up when it's switched or when it's powered? And also, how hot is hot? Can barely touch? Mildly warm?

 

[wildburkey]

Cook an egg on kinda hot, it's definitely not right. I realise it's not a STC, that one is what I have replaced the stc with for testing until another arrives. Cheers

 

[wildburkey]

Here's a cpl of pics of the completed project with a single relay control.

 

[Tropico]

I found that mine got quite hot when either the heat or cool relays were on. You could test this by setting the Temperature set value around the current temp and Difference set value to 10.0C, so that neither heat nor cool are on.

 

[wildburkey]

Cheers, but it just isn't right. It started melting on the last test I done.

 

[Tropico]

Cheers, but it just isn't right. It started melting on the last test I done.

That doesn't sound good. If you are going to bin it, open it up first to see where or what it has started to burn on the inside. Just out of interest.

 

[wildburkey]

I'll be seeing if I can salvage the relays from it, it seems to be a tranformer just at a guess from where the heat is coming from. I'll keep you updated.

 

[dblunn]

The internal power supply (240Vac to 12Vdc or maybe 5Vdc) is the most likely suspect. If you're keen to do a bit of electronics you could replace the PSU with an external one since it will all end up in an enclosure anyway.
Dave

 

[ctagz]

I wired one up yesterday STC-1000

Brown - Live going into port 1 and 7 (jumper from 1 to 7)
White - live to compressor coming out of 8
Blue - neutral going out of 2

In fridge originally brown was split into two reds, thermostat and light
Blue went from light
White out of thermostat
Green - earth out of thermostat.

its my understanding that a faulty thermostat will keep power to the compressor going and you will accumulate frost and whatnot in the fridge

I have not given mine a good run yet to see if it does heat up but will be checking it carefully when i do now, so thanks

 

[hellbent]

wonder how many fridges have stuffed up and how many fires have been caused by these DYO sparkys setting up a STC1000???

 

[Ducatiboy stu]

I'll be seeing if I can salvage the relays from it,

My experience over the years says its not worth the hassle. I have found that component failure tends to propagate when high voltages are involved.