# disabling auto-shutoff on a pcb



## dorado29 (Oct 6, 2008)

hey guys, not sure if this really counts as "home improvement"...

I just went out and bought a heat pad: http://www.kaz.com/kaz/store/product/550cd6b67e55a279c68afdf93febaa8b/


it has a 60 minute auto shut off, apparently most heating pads have them so people don't fall asleep on an extremely hot pad/ harm themself. I really need this to be disabled but after googling and looking over my circuit board, i realized that mine and the pcb in this "how to" guide were very different


http://www.ralree.com/2007/12/13/disabling-auto-off-on-the-sunbeam-health-at-home-heating-pad/

i was hoping they would slightly resemble each other :laughing:

heres the inner workings of mine



















any thoughts on what i should try or look for to get the 60 minute timer shut off?


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## jbfan (Jul 1, 2004)

You will not find anyone here to give instructions on how to disable a safety feature!!!!


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## dorado29 (Oct 6, 2008)

it's not a safety feature in this case. I keep reptiles, and a popular way to heat tanks is with a heating pad similar to this

http://www.petco.com/product/6353/Zoo-Med-Repti-Therm-UTH-Under-Tank-Heaters.aspx

$15 at target + disabling their silly auto shut off vs. $45 at petco for a non-adjustable, large heat pad

I already contacted the manufacturer, they confirmed that continual use is okay, but they were not allowed to supply any information that could potentially make the product harm someone who loses consciousness and burns themselves. This is going under a terrarium lol; if it gets too hot for some reason then, in the process of thermoregulating, the snake will just go to the other side of the tank.


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## Yoyizit (Jul 11, 2008)

It'd be easier to make your own fixed-level control, unless you need it full on all the time. All you need is an incand. lamp.


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## dorado29 (Oct 6, 2008)

Yoyizit said:


> It'd be easier to make your own fixed-level control, unless you need it full on all the time. All you need is an incand. lamp.


It has to be on 24/7, running on low (possibly even lower than the lowest stock setting) I'll have to check the temperatures more accurately than just feeling it lol, but low *should* suffice

Are you saying that i should essentially cut the wires in between the controller and the pad and wire this up so that the heat pad would act like the "bulb" in the lamp assembly? I'm new to almost everything electrical so bear with me please :whistling2:


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## Yoyizit (Jul 11, 2008)

I couldn't find the wattage draw on your blanket, but if you put the blanket (no controller) in series with an incand. lamp, 7-1/2w will put very small power into the blanket, larger will put more power into it. 
You adjust the lamp size to get the heating you want. The lamp may or may not glow.


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## dorado29 (Oct 6, 2008)

it says on the pad "120 bolts AC / 45 watts," so if 45 watts sounds reasonable then thats probably it haha

im guessing that i would rig this up to a 45 watt incandescent lamp? 

how should i go about doing that?


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## Yoyizit (Jul 11, 2008)

dorado29 said:


> it says on the pad "120 bolts AC / 45 watts," so if 45 watts sounds reasonable then thats probably it haha
> 
> im guessing that i would rig this up to a 45 watt incandescent lamp?
> 
> how should i go about doing that?


In the diagram below, 
http://www.ftschool.org/fourth/science/images/seriesCircuit1.gif
120vac substitutes for the battery. 
The blanket substitutes for one bulb. 
If you use a 50w, 120v bulb for the other bulb the blanket will run at less than full power. For even less power into the blanket use a 25w or a 10w bulb.

Use wiring that can stand 120 "bolts" of AC. 

If you're unsure about what this all means, don't do it.


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## dorado29 (Oct 6, 2008)

rofl. ya' got me

im still getting used to my keyboard, its hard to go from a really small laptop keyboard to an ergo-curve keyboard imo :laughing:

so let me get this straight:

Step 1: Cut heating pad cable somewhere between the pad and the controller

Step 2: Find a small incandescent lamp that's 120 "bolts" and maxes out at ~45 watts (right?)

Step 3: Take the now cut and slightly separated wires that go to the heating pad and connect them to the two points in the lamp which I'm assuming are positive / negative.

****How should i safely connect the pad's wire to the lamp's (for lack of a better phrase) input / output?****

Step 4: Use the handy lamp dimmer I have lying around that goes into wall sockets then plug the incandescent lamp into that

Step 5A: Turn it on
Step 5B: Pray

Step 6: Dial in the temperature using the lamp dimmer

How's this sounding?


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## hayewe farm (Mar 15, 2009)

From what you are asking and what you are posting I would suggest you spend the $45 and get the proper unit before you burn the house down.


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## jamiedolan (Sep 2, 2008)

hayewe farm said:


> From what you are asking and what you are posting I would suggest you spend the $45 and get the proper unit before you burn the house down.


:thumbup::thumbup::thumbup:
Jamie


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## rgsgww (Jul 5, 2008)

I am all for modding electronics, but not devices like these.


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## dorado29 (Oct 6, 2008)

lol..

i suppose i forgot to mention that i'm going to have it looked over by my parents' friend, an electrician. I don't want him to have to do all the work in putting it together


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## Yoyizit (Jul 11, 2008)

You could use a lamp dimmer but some have a minimum load, probably 40W.


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## hayewe farm (Mar 15, 2009)

Here's the problem with answering your questions. None of us have a schematic of the device. On one end you have a 2 cond cord the terminals are are marked "L" and "N" so I would guess that is the power cord. The other has 3 wires. That could be 3 separate heating element connections or it could be 2 element connections and a thermocouple connection. Operating without the thermocouple connection you could have the element over heat and cause a fire. We also do not know if it actually provides the 120 VAC to the elements and connecting direct could cause a fire. Modifying and experimenting with electricity if fine but not for a device that is likely to be left unattended and providing heat. To endanger your home or yourself just to save $30 is just insane.


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## dorado29 (Oct 6, 2008)

i went to the store and found a sunbeam model like the one that the tutorial is based off of. I have that plugged in as i watch it for a few hours to make sure it doesn't asplode or shut off after 2 hours


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