Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[bigegg]

I am repairing a reclining chair for a friend.
The transformer which powers the recliner motor and massage/heater is busted.
It is a standard iron cored toroidal transformer rated 12v 3A AC

Would I be able to substitute a 0-50W electronic low voltage lighting transformer?
I'm specifically looking at a YT50L from "varilight", because it is specced 0W output - if the motor, massager and heat pads are off, there is just a small LED to show power is connected -and I'm not sure what the failure mode is.

I don't know enough about electronic transformers to know if they can be used on inductive loads - or only resistive.

[pscocoa]

I would get a proper replacement - I recently had to do one for my mother which was buzzing and did not want to mess about with circuit boards when a replacement unit complete wasn't that pricey. Is there an electrical fire risk. We had to get unit pat tested.

[zirk]

Its not so much a like for like Transformer, its more to do with any DC Rectification after it thats important (could also be switch mode?), personally unless your really up on the subject, I would recommend you go down the proper Manufactures Parts route.   

[bigegg]

proper replacement is from the states and starts at 90US$ + shipping + VAT + taxes +

I could just buy another iron wound transformer, and swap the plug over, but this unit I'm looking at has terminals so I can just wire it up that way - also has the advantage that it's much lighter and smaller, so can be mounted inside the chair, instead of left on the floor to be run over with a wheelchair - which is what happened to the last one.

PAT testing not relevant - private house.

When I say "transformer", "power adaptor" might be nearer - like a big wall wart, not just an electronic component.

[Rods2]

I would replace like with like by getting a 12v 3a toroidal transformer.

[Andy H]

One of these will give you 4 Amps with both windings connected in parallel.



http://www.maplin.co.uk/p/2x12v-208a-toroidal-transformer-n22jb

[Andy H]

Do you know what kind of motor is fitted? Does it want AC or DC?

If AC then the neatest solution would be an 'old school' low voltage lighting transformer with a transformer inside a case with terminals for you to connect to.

If it wants DC then you may be able to find a 12v 3A DC wall wart. Alternatively cased 12v DC switch mode power supplies are fairly easy to source.

An electronic low voltage lighting "transformer" is going to be a bit of a lottery. It could be doing something horrible to the output because 12v halogen lamps aren't going to notice.

Can you post a picture of the power supply that died?

[bigegg]

Can't post a pic - camera on my phone is FUBAR

it's a bog standard iron cored transformer in a plastic case - NOT toroidal, sorry, it's the sort where the iron core is made up of lots of iron laminations in the shape of an 'E'

It has four wires connected - two from the low voltage side.
two from the mains side.
no other components.

The low voltage transformer I'm looking at *is* the sort with screw terminal - I will be able to cut the wires from the old transformer, strip the ends, and connect them straight into the terminals

[zirk]

You mean like this, only a 3 Amp + version?, if so then Maplins, CPC, Farnell, RS Components etc.

[zirk]

Here ya go Maplins.

And if like you said your thinking of mounting inside the Chair, dont, they get warm and need ventilation. 

http://www.maplin.co.uk/p/12v-3a-chassis-transformer-n60jb

[I_want_an_Omega]

IMHO - if you use anything other than one supplied by the manufacturer & for this specific model then you would contravene it's "approval" and maybe household insurance in case of fire etc.

Even worse doing it for a friend -  my suggestion is get them to pay up for the "correct" replacement and keep things above board .....

[Andy H]

Can't post a pic - camera on my phone is FUBAR

it's a bog standard iron cored transformer in a plastic case - NOT toroidal, sorry, it's the sort where the iron core is made up of lots of iron laminations in the shape of an 'E'

It has four wires connected - two from the low voltage side.
two from the mains side.
no other components.

The low voltage transformer I'm looking at *is* the sort with screw terminal - I will be able to cut the wires from the old transformer, strip the ends, and connect them straight into the terminals

If it says "electronic" anywhere then it isn't a traditional transformer and not suitable for powering a motor.

12V 3A is only 36watts. That doesn't seem enough to power seat motors and heaters. Is it possible that the 3A is the mains input? 230V at 3A is 690W. £90 doesn't seem so unreasonable for the genuine article if that is the case.

[Kevin Wood]

Yep, get a proper transformer. Many lighting transformers will be switch mode converters and unsuitable for this application. A decent quality toroidal replacement from Mapin, Farnell, RS, Rapid components, etc. will be a much better bet and they are not expensive.

[pscocoa]

http://www.bfworkshop.com

I used these people - prices ok and delivery prompt.

[bigegg]

Can't post a pic - camera on my phone is FUBAR

it's a bog standard iron cored transformer in a plastic case - NOT toroidal, sorry, it's the sort where the iron core is made up of lots of iron laminations in the shape of an 'E'

It has four wires connected - two from the low voltage side.
two from the mains side.
no other components.

The low voltage transformer I'm looking at *is* the sort with screw terminal - I will be able to cut the wires from the old transformer, strip the ends, and connect them straight into the terminals

If it says "electronic" anywhere then it isn't a traditional transformer and not suitable for powering a motor.

12V 3A is only 36watts. That doesn't seem enough to power seat motors and heaters. Is it possible that the 3A is the mains input? 230V at 3A is 690W. £90 doesn't seem so unreasonable for the genuine article if that is the case.

definitely 3A output (actually 2917mA).
It doesn't power the seat motors - just the massage bit, possibly a heater.

I'm going to find a 3A wall wart - I think I may already have one in the shed.

Thanks for all the advice/info