Need to find 6 pin pcb transformer 120 to 12

I am searching for someone that can direct me in replacing a power transformer on a circuit board. A friend of mine asked me to get her electric hospital bed working again. She recently had to be cut out of a pick-up after a head-on collision and still needs an electric bed.

This is what I have so far:

The bed doesn't have a brand name but did have these numbers handwritten on a factory checklist 97-85600 0010411 9-18-89

The control box has 2-MOT., 2-VIB. CONTROL BOX ASSY PART NO: 5585550 / SERIAL NO: W0010411 (and also has a bar scan)

The circuit board has SCI-O-TECH 5201003 It has eight relays, all with 12 VDC coils

The transformer has PSC-244 EIA696B-8850 without any other info. It is a six pin transformer mounted on the circuit board. There are three spade terminals next to the transformer, Line, Neutral and Ground, where the cord connects.

I measured 120 V at the terminals and found 120 V at the transformer, but could not find any low volt output. There are no fuses. I don't have a pin layout for any six pin transformer and need help finding a replacement or another idea. I did try to find the board through a medical parts suppier, but they could not find anything with the numbers I gave them. I don't know who made the bed, which is why I didn't get too far with the parts supplier.

Reply to
dnba
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:I am searching for someone that can direct me in replacing a power :transformer on a circuit board. A friend of mine asked me to get her :electric hospital bed working again. She recently had to be cut out of :a pick-up after a head-on collision and still needs an electric bed. : :This is what I have so far: : :The bed doesn't have a brand name but did have these numbers :handwritten on a factory checklist 97-85600 0010411 9-18-89 : :The control box has 2-MOT., 2-VIB. CONTROL BOX ASSY :PART NO: 5585550 / SERIAL NO: W0010411 (and also has a bar scan) : :The circuit board has SCI-O-TECH 5201003 :It has eight relays, all with 12 VDC coils : :The transformer has PSC-244 EIA696B-8850 without any other info. It :is a six pin transformer mounted on the circuit board. There are three :spade terminals next to the transformer, Line, Neutral and Ground, :where the cord connects. : :I measured 120 V at the terminals and found 120 V at the transformer, :but could not find any low volt output. There are no fuses. I don't :have a pin layout for any six pin transformer and need help finding a :replacement or another idea. I did try to find the board through a :medical parts suppier, but they could not find anything with the :numbers I gave them. I don't know who made the bed, which is why I :didn't get too far with the parts supplier. : :

The manufacturer of your bed is SCI-O-TECH and according to this website they no longer make hospital beds

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SCI-O-TECH was acquired by LUMEX INC in 1995

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Further investigation seems to indicate that Graham-Field Medical

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acquired LUMEX. Their website lists LUMEX as one of their brands.

Their bed products are listed here

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You might contact this company for support (no pun intended) for your bed.

Reply to
Ross Herbert

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Hospital suppliers will not sell you electrical/electronic parts. They want to sell you new unit. Your help is helpless.

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Reply to
Michael A. Terrell

It is likely that an internal thermal fuse buried in the transformer's primary winding has failed. This being the case, it should be an easy job to measure the secondary of the transformer with an ohm-meter to determine its configuration. I would expect the most likely to be a single centre tapped winding, in which case, your meter will read pretty low ohms between all three secondary terminals.

Have a look to see if there is a bridge rectifier, and two smoothing caps. If there is, then the centre tap will be connected to system ground, and the bridge will be producing a negative and a positive rail, with respect to ground. You can get a pretty fair idea of the secondary voltage by looking at the voltage rating of the smoothing caps following the bridge. Take about

20% of that voltage, and then multiply the result by 0.7. So, if caps rated at say 25v, take off 5v = 20v and then multiply that by 0.7 = 14v, so transformer would likely be rated either 12v - 0 - 12v or 15v - 0 -15v. There may well be 12v regulators like 7812 and 7912 following the bridge, and 20v input would be a good figure for these.

As far as current rating goes, that's really just guesswork and experience. If the transformer is just powering some electronics on the board, then it's unlikely that the current draw is going to exceed 500mA, assuming that all those relays are not activated at once at any time, which I doubt, so any transformer around about 6vA rating that's the right physical size to go in, could be used. It does not *have* to be a PCB mounted type. It could be a clamp mounted type screwed to the board, or elsewhere in the enclosure if there's room, but if you do screw to the board, be very aware of any line voltage tracks, and where your screws come in relation to them. Best to use nylon nuts and bolts.

At the end of the day, it's not working now anyway, and it seems that there is little liklihood of getting genuine service assistance with parts, so you've got nothing to lose by having an educated go at replacing it. Worst that can happen is that it gets a bit worse than it is now, which is all part of the *fun* of this sort of project ... Hope your friend gets well soon, and you are able to help her with this.

Arfa

Reply to
Arfa Daily

I think the bed is working with electrial moter. As you decribe that transformer is confired with 6 pin. Here I would like to see that how many pin is on primary side and how many on secondary side.if you can trace the pcb you can find it.If 3pin on secondary side then the transformer may be 6 0 6 type and that may be connected to diodes to make AC volts to DC volts.can you trace the pcb connection if yes than trace it and send it to me or take picture of that pcb from front and back.So I can see it and I can guid you for the same.If the transformer is not available we can try to modify and start the unit.

Reply to
Vina.Electronics

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Probably true but you never can tell. If he can get past the Sales Droids, there might be someone in tech support who could at least provide the specs. Else find a company that sells medical/hostpical surplus equipment

Stranger things have happened.

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Reply to
Sam Goldwasser

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Reply to
Michael A. Terrell

On Sun, 9 Mar 2008 02:36:40 -0800, "Michael A. Terrell" wrote:

: :"Ross Herbert" wrote in message :news: snipped-for-privacy@4ax.com... :> On Sat, 8 Mar 2008 21:07:57 -0800 (PST), snipped-for-privacy@hotmail.com wrote: :>

:> :I am searching for someone that can direct me in replacing a power :> :transformer on a circuit board. A friend of mine asked me to get her :> :electric hospital bed working again. She recently had to be cut out of :> :a pick-up after a head-on collision and still needs an electric bed. :> : :> :This is what I have so far: :> : :> :The bed doesn't have a brand name but did have these numbers :> :handwritten on a factory checklist 97-85600 0010411 9-18-89 :> : :> :The control box has 2-MOT., 2-VIB. CONTROL BOX ASSY :> :PART NO: 5585550 / SERIAL NO: W0010411 (and also has a bar scan) :> : :> :The circuit board has SCI-O-TECH 5201003 :> :It has eight relays, all with 12 VDC coils :> : :> :The transformer has PSC-244 EIA696B-8850 without any other info. It :> :is a six pin transformer mounted on the circuit board. There are three :> :spade terminals next to the transformer, Line, Neutral and Ground, :> :where the cord connects. :> : :> :I measured 120 V at the terminals and found 120 V at the transformer, :> :but could not find any low volt output. There are no fuses. I don't :> :have a pin layout for any six pin transformer and need help finding a :> :replacement or another idea. I did try to find the board through a :> :medical parts suppier, but they could not find anything with the :> :numbers I gave them. I don't know who made the bed, which is why I :> :didn't get too far with the parts supplier. :> : :> : :>

:> The manufacturer of your bed is SCI-O-TECH and according to this website :> they no :> longer make hospital beds :>

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:>

:> SCI-O-TECH was acquired by LUMEX INC in 1995 :>

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:>

:> Further investigation seems to indicate that Graham-Field Medical :>

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acquired LUMEX. :> Their :> website lists LUMEX as one of their brands. :>

:> Their bed products are listed here :>

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:>

:> You might contact this company for support (no pun intended) for your :> bed. : : : :Hospital suppliers will not sell you electrical/electronic parts. They :want to sell you new unit. Your help is helpless.

While your assumption is generally the case where run of the mill domestic appliances are concerned, particularly when manufactured overseas, items such as hospital beds which are sometimes manufactured locally, can be easier to get parts for. It is one thing to put a TV or washing machine on the kerb on council pick-up day but you can't do the same thing with a hospital bed. Manufacturers will sometimes help to supply parts to individuals rather than a new bed if you speak nicely to them.

If their bed products are supplied under contract to a large hospital for example, I'll bet they do electrical repairs and replace parts rather than try to sell a new bed to the hospital every time one breaks down. If they didn't offer this service they wouldn't get another contract.

Anyway, the OP has found the problem and fixed it so he doesn't have to contact the manufacturer.

Reply to
Ross Herbert

Check to see if the bed is for 120 and 240 VAC operation. This may mean the transformer is 120/240, the reason for the extra windings. Mouser carries a lot of PCB mounted transformers.

Jimmie

Reply to
Jimmie D

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