Plug Rewire

[thisisgazza]

Hi everyone, new to the forum and really new to electricals too so would really apreciate your help.

I recently purchased an electronic plug-in temperature controller. The idea was, when the temperature got to 25c, the plug would turn on and operate the cooling fan, to bring it back down to temperature in which it would turn back off. BUT in my error it works the other way round and is for heating.

Now looking inside the box, im guessing its just a matter of switching the on/off wires with each other? Could you look at the pictures below and tell me which wires i should be swopping around?

Thanks for your help

Andy

 

[Doomed]

If you had to ask this question I would advise you not to touch anything!

However, the temperature controller should operate a relay that allows the circuit to be completed. The relay should have another output contact that is not connected to anything. The wire connected to the existing output contact will have to be moved to the unconnected contact.

As the unit you purchased seems to be all soldered and sealed onto a small PCB I will again say DON'T TOUCH IT.

 

[thisisgazza]

Howdy,

thanks for the reply and I understand your caution.

My father knows a few things about re-wireing so will run it by him before anythings done. Just wanted to get some facts before i show it him.

Right having looked at the connections iv narrowed it down to the 2 small blue wires.

You say that these cannot be simply switched round so the circuit is completed in reverse, correct?

I will take some more pics close up tonight.

Thanks

 

[Doomed]

Ack!

Definately get someone else to look!

Not sure from the picture, but very high probability its not the 2 blue wires.

 

[Darkwood]

Dont quote me as a 2d pic is not too easy to give a reliable answer but it looks like the black box is your relay and you need to swap the orange wire to an adjacent empty solder pin, im assuming as its hard to work out that the red and orange are not connected together but to seperate pins at the bottom right.
As mentioned before if your asking this question in the first place dont get involved as my advice is limited as i only have a picture to go by.

 

[thisisgazza]

Hi, thanks for the reply darkwood.

Ive taken a few more pics, let me know if these help you out. Need another pic, let me know and i shoot it ya.

Thanks again

 

[Darkwood]

Thanks for the bigger photos, by the looks of it you dont have a spare contact point on this relay its just has one set of contacts so you cant do it without replacing the relay, for your info thick red is feed and orange is your switch wire with the 2 blues been your coil supply to relay and the thinner red is the feed to the control board passing through the parallel resistors which also has a thick blue neutral, the yellow unit looks like a mains filter/suppressor unit.

 

[Mr Brady]

Here's a relay with changeover contacts but only you can tell (by measuring and comparing) if it will fit: SCHRACK COMPONENTS|RTD14048|RELAY PCB SPCO 48VDC | CPC

 

[thisisgazza]

Thanks darkwood for the excellent explanation.

Right, so what your saying, with these components i cannot do anything with?

So, next question, can the relay be swopped as Brady suggested(allthough that particular one wohnt fit,unless the width overhang doesnt matter?. my dimensions are Length =29mm, height = 20mm, width = 13mm). Or would it be easier to make a circuit from scratch to replace that bit?

Thanks again

 

[Darkwood]

You need to find a relay that will be the same coil voltage have the same switching contact rating and fit the board, but make sure it switches the opposite way round ie.. if the existing relay is n/o (normally open) then you need a n/c (normally closed) and vice versa i cant tell from here.
For all its worth its probably easier to build a cheap one with a room stat and socket outlet if all your going to run on it is a fan, as long as you stat has both contact terminals and is rated to what you plug in.

 

[thisisgazza]

Hi thanx for the reply.

Iv looked on the net and this is what it is Hong Kong SAR Power Relay. Exporter

Im guessing from the symbol on the relay that it is N/O?

What uk websites should i be looking at to buy these parts from?

Can i not just build that little section and then just solder all the wires back to it. I have 2 of these plugs you see, otherwise they wohnt be any good to me.

Bascially i have a marine aquarium tank and recent hot weather has made my tank temperature go well over what it should be. The idea was place external fans to blow onto the water surface cooling it down, the second plug would blow cool air around the room. As soon temperature drops below whats needed then the fans would cut off waiting for the next temperature rise. Hope that makes sense?

thanks again

 

[Mr Brady]

@thisisgazza
If you are going to build the relay section yourself, then the relay I linked to in post no.8 has the right coil voltage and contact ratings, or at least it matches the ratings shown in your pictures.
Good luck, or will you give it to your father to play with?