Fixing a plug with a circuit board

King

We recently had a pin snap on a plug for an air filter we bought, so I decided to replace the plug head.
When opening it up, I discovered there's a small circuit board inside - I can only assume this helps with the controlling of the filter (it has 3 speed options).
When looking for a new plug housing, is it simply a case of finding a similar one which has space for the circuit and swapping over as best I can, or is there something else I need to look out for?
I'd appreciate any advice or tips

grumbler

It's a low voltage power supply. The broken part is needed only to open the socket when you plug it in.

Options

• Use some plastic object to open the socket manually every time you plug it in
• Buy a new PSU with the same voltage and power/current and re-solder the wire. Power/current can be higher.  Make sure you keep the same polarity (+ and -).
  
• Plug it in to a small adaptor or an extension lead and unplug the adaptor/lead when needed

Mutton_Geoff

Is there a plug into the filter on the the other end of that cable or is it hard wired into the device? As grumbler said, it's a 12v power supply (PSU) not anything to do with controlling the filter. If you hadn't taken it apart, you could have safely filed down the plastic where the old "earth" pin was since that was probably just a plastic leg not connected to anything as the supply has a double insulated symbol (double box) and does not require an earth (the only leads coming out of the PSU are the +/- 12v leads).

It's too risky to try to reassemble it now as you may leave exposed parts so just buy a replacement PSU and

Interestingly the label says it has a T1A (T means "timed" or slow blow at 1 amp). Since the PSU is rated at 1000ma (ie 1amp) then it's strange fusing it at that value. In any case, I can't see a fuse anywhere so it's probably just another exaggeration in the same way as the CE label ;-)

If you have a small plug into your filter at the other end, finding a drop in replacement is easy. If it's hard wired, you could try one of these power adaptors with little connector blocks. You could cut the red and black wires, strip them carefully about 2-3mm and attach them to the screw terminals. Red is +, black is -.

This item is a direct replacement but I might be tempted to go for the 2A version for more reliability - https://amzn.to/2Z3n1Xt - 12v 1A supply.

King

Thanks for the replies, extremely useful.

FreeBear

grumbler said: It's a low voltage power supply. The broken part is needed only to open the socket when you plug it in.

Options

• Use some plastic object to open the socket manually every time you plug it in
• Buy a new PSU with the same voltage and power/current and re-solder the wire. Power/current can be higher.  Make sure you keep the same polarity (+ and -).
  
• Plug it in to a small adaptor or an extension lead and unplug the adaptor/lead when needed
  

First option - Very dangerous and not advisable. UK plugs & sockets use the earth pin to open the gate covering the Live/Neutral contacts to ensure it is safe and small objects can't be pushed in (important point with small children in the house).

Option 2 - The best choice. A 12V 1A power supply is fairly common, and may well come with the right sort of plug on the end. Look around for universal power supplies, and you'll find one with interchangeable low voltage plugs for not a lot of money.

Option 3 - Still has the same issues regarding the safety gate in option 1.

Option 4 - Glue a new earth pin on to the power supply. However, the the glue joint fails (which it probably will), the dangers mentioned in option 1 come in to play.

Buy a new one - These things are not designed for repair, and the casing is often glued together to prevent it being opened. Looks like the OP had a good fight with it and may have damaged the casing in the attempts to open it up.

Jumblebumble

FreeBear said:y.

Option 3 - Still has the same issues regarding the safety gate in option 1.

Option 4 - Glue a new earth pin on to the power supply. However, the the glue joint fails (which it probably will), the d

If the earth pin gate mechanism is flicked down with a small screwdriver just enough to let the power pins in then I can see no danger in Option 3 as we are only interested in what happens when the charger is removed
If something is left in the earth pin hole then I agree it it unsafe

Ectophile

If you are buying a replacement power supply, try to check that the polarity of the plug matches the appliance.

If you look at the picture posted by Mutton_Geoff, just above the "Made in China", is a magic graphic that tells me that the outer sleeve of the plug is negative and the centre hole is positive.  Unfortunately, your old power supply doesn't have that logo.  Maybe the air filter itself does.

Rodders53

Mutton_Geoff said: In any case, I can't see a fuse anywhere 

Look again. Its the black block at the bottom of the unit, adjacent to the VR1 marking.
https://uk.farnell.com/multicomp/mst-1a-250v/fuse-radial-slow-blow-1a/dp/1566100

The psu and connector you've suggested should work fine though with the cable to the unit cut off:   red is invariably + ve  and black - ve connection.