Disabling Auto-Off on a Sunbeam Health at Home Heating Pad

Statement of Empiricism
I have used this heating pad for several years now (I wrote these instructions in December 2007, it's now February 2011).  I have had exactly ZERO issues with it - it works perfectly and the hedgehog is fat and happy.  YOUR MILEAGE MAY VARY!  PLEASE USE EXTREME CAUTION IF YOU FOLLOW THESE STEPS.  If you do this, closely observe the pad for at least a few days to make sure it's not overheating or catching on fire.  See the obnoxious red text below:

WARNING! DONT BURN DOWN YOUR HOUSE!
USE CAUTION! TRY AT YOUR OWN RISK!
YOU WILL VOID YOUR WARRANTY!

So, I got this heating pad at the store a while back to use as a hedgehog heating pad. I found out that the 2-hour auto-off timer was hardcoded into the circuit, and they didnt even bother to put a switch on the casing to disable it. Typical overprotection of the consumer - this wouldnt exist if our country was a bit less litigious.

African hedgehogs need at least 72F to be happy, so a heating pad under the cage is recommended. I mean, how could you say no to his face?

So, to disable it, I decided to take it apart and find the culprit like this guy did. Its too bad that for some reason they decided to make it even harder to change this feature.

Step 1: Surveying the Situation

Here, we can see the circuit board and outer casing.  It’s an Eagle LOPP4, and apparently it was made on Christmas of 2006 (2006-12-25)! It also bears a marking of 07.28, and I have no idea what that means.

Step 2: Doing the Modification

So, the deal is that after a lot of trial and error, I finally found which single pin on the IC you have to cut. I’ve circled the IC in the picture below.

It’s PIN #2!

OK, it actually isn’t #2 on the schematic, but in the picture it makes sense. Just take a soldering iron and a sharp pointy object (I used a thumbtack), melt the solder, and pry the pin from the board. Be careful not to touch pin #1 - if you disconnect it, it will turn off every 5 minutes! Then, put the entire thing back together and celebrate!

I used the datasheet for the IC chip to figure out what pins to screw with. I can’t find the number of the chip right now without tearing the whole thing apart again. Basically, the chip is just a counter, and you cut one of the pins that makes it increment. So simple.

Step 3:

Now I have a happy hedgehog. He’ll never be cold again.

Step 4: Also, the Sunbeam Model 836

Nick V has modified his Sunbeam Model 836. For those interested, here’s his description of the mod:

The chip is a CD4060 (14 stage ripple counter) on mine. They use it as count up timer to turn the ac to the heater coils off after two hours. I wired in a 10k resistor pullup to Vdd to pin 12 (master reset). This disables the counter function, and voila, no auto off!

I went ahead and found the datasheet for all you kids looking to try this. I extracted the one piece of information you probably need, which is in the attached picture.

Nice job, Nick! Hats off to you!

Comments

[KainB]

How do we remove it off a "LOPP4 2014 05-28" ? (No quotes)

[fserfgh]

Every heating pad available today(2022) has been made with a microprocessor and has been programmed for the most ridiculous nanny-state safety making it pretty much useless. (Electric blankets have same issue. They tend to Auto-Shut Off before you have completed a nights sleep.)
Auto-Shut OFF in 2 hours - no good. On power up it wakes up in OFF mode requiring button presses to turn back ON so an external timer to try to reset Auto-Shut Off time is no good.
Instead of two coils like in the old days to allow 3 power levels they only have one coil and the control circuit pulse modulates for temperature control.
Even if you figure out how to bypass the chip's Auto-Shut OFF you still have the possibility of a power surge damaging the chip and it pulse modulates at full power and cooks your feet or your animal. So adding a semiconductor to the circuit actually detracts from safety and adds the possibility of dangerous over heating.
So the easiest thing is to just cut the control off and throw it away. Rewire the cord to plug into a variac transformer and set it for a voltage that will give the desired output heat. Of course this requires a $70 variac. Or you might search through your scrap transformer box for a voltage that is suitable.
Or buy a cat heating pad which is already set for a very low heat level. Not too bad but my cats tend to crowd out my feet from my heating pad. But actually sticking my cold toes under my warm cat is rather pleasant if they would just stay there.

[JonathanM116]

I have a new Walgreens heating pad the board number is 109375N the chip is 18 pin and reads SONIX N8P2602BSB 102QNKB14 I have reptiles and I am trying to disable the two hour shut off

[dsamual]

after some digging on Internet, I've found datasheet for IC. Can anyone PLEASE help me with which pin?
I've currently got 3 different heating pads all doing the flashing red light.
one is the same as yours, other is HP215
I have IC pinout for sonix 18 pin IC but it won't let me post

[wimspeed]

This is the datasheet for the 109375N: https://pdf1.alldatasheet.net/datasheet-pdf/view/3... , a SONIX SN8P2602BS. Anyone has an educated quess on how to bypass the #G86$%! autoshutoff?

[dsamual]

here is the 18 pin Sonix IC pinout. JohnathonM116 and myself have same pad.

Can anyone PLEASE help me? I also have the data sheet which had more info

[KimbieH]

Did you ever figure this out?

[dsamual]

I know this is old, but I'm having red blinking light. Hold power and plug in, see green light for a second then back to red blinking. Did you ever find out how to fix this?

[smoph]

I just got this sunbeam heating pad, with a controller that looks quite similar but the circuit board looks entirely different. I was hoping to be able to turn the auto off on this safely. I've looked around and could not find any clear instructions on how to modify this. Do you know if it's possible with this model?

[DatabaseBen]

it looks like you bought the "none" auto-shutoff model. i have several of these that do not auto shut-off. but they are hard to find these days.

to double check, if your model had "auto shut-off", it would clearly be cited on the front side of the box. but you have the old fashion type pad. :-)

[flutterbie.butterflie]

Here's an even simpler solution..buy/order an outlet timer. I already had one that we used to use for the lighting system on our aquarium.. Simply set it to turn off&right back on every 115mins which will reset the auto off timer each time you do resulting in a heating pad that never turns off! Voila! Problem solved without risk of being charged with arson after I burn down my entire neighborhood. Which is very likely...I once burnt my parents entire coffee table down along with the rug underneath and part of the love seat all cuz I wanted to make smores in the middle of the night and thought it'd be a good idea to use my moms lighter to toast the mini marshmallows. I learned very quickly I was indeed wrong...it was a terrible idea. I'll never forget that night going in to wake my mom up,talking so faintly soft &quiet "mom, mom, hey mom..mom the livingroom is on fire.." She replies" bugsy, go back to bed" then you just hear this awful screechy scream sounding like someone was being murdered but no,it was just my sister trying to scream the living room was on fire but seeing how she just woke up from a dead sleep to go use the restroom,she was so confused and in a panic that none of those words were coming out..just horrendous sounds. So my mom jumps up and damn near runs me over to go see wtf is happening at which point she sees the fire & screams "bugsy wtf did you do?!" I calmly replied, "i told you the living room was on fire. I'm sorry. I just wanted smores" and I began to sob as my mom&brother,who woke up and rushed out&helped my mom quickly put out the fire&go straight back to bed,never saying a single word,like a damn super hero. I'm not even sure if he was really awake. My mom scolds me,sends me to bed,&goes back to bed herself where my dad was still snoring..straight slept thru the entire thing. He was pretty shocked to wake up to a partially burnt living room. In my defense I was only 7.

[boogiethecat]

This also works SUPER weLL on the little heated sunbeam throw blankets that Costco sells.
THANK YOU for the cool tip, it was that easy. Prior to reading this I used to just cut the controller off, hook AC to the white and green wires of the blanket (black is a heat sensor), take my chances on not overheating and plug the thing in. For lower heat I'd put a cheap light dimmer in series with the AC to the blanket, it worked really well but your solution is even better!! THANKS

[Naceanator]

Can someone tell me how to stop timer on a heat pad

[Naceanator]

TC25B1-04

[JohnS1115]

Wow! Worked great!! It's actually PIN #10 on the diagram, and the LOPP4 NEW uses the HEF4060B which is very similar chip. When looking at the name up the chip, it will be the 2nd from the right, top side. I did not have a soldering iron, nor a clipper small enough. I instead took an etching knife and cut the connection on the board from the chip to the component that was laid out on the board. That would be the Rtc Oscillator Pin pin connection that I cut. Now my chickens are nice, warm, and happy.
Also, the screws were a weird type of tri-shaped y. I however was able to use a small star-type screw bit, and they all come out just fine!

[Bobbyrab54]

I have the Sunbeam Heated Back Wrap with 4 heat settings Warm,Low,Med,and High with 2 hour shut-off.The controller is somewhat different than the one in your drawing. My model is SW115D to be used with pads model CAT94M E4738193. On mine,the counter IC has a dot on top left of IC denoting pin 1.I tried disconnecting pin 2 right below pin 1,put it together plugged it in,and nothing,no light no heat. I now have another,the same model,and I dont want to fry this one.please,tell me how to disable this timer so the pad stays on until I turn it off,and still has each of its 4 heat settings.Also,if there is a way to increase the time from 1 hour to 10 hours,that would even be better.Please help and explain to me how to do this successfully.Thank you.

[ChristopherS358]

I do industrial machinery and have soldering experience. The problem I have with projects around the house Is the ability to find the data sheet for chips like this so I can modify them to fit my purposes around the house and work. Larger factory equipment I can usually contact the machine provider and get information on the hardware and most is included with it.

[SteveDay72]

After making sure you have correctly identified the pin you can simply cut the PCB trace that it connects to. Cut it in a place that can always be patched with a wire/solder-blob later, just in case you want to reverse the hack.

[SteveDay72]

My heating pad was a newer version. The PCB was marked "LOPP4 NEW". The design is tidied up a little, but otherwise the same. It still uses a 4060 14-stage binary ripple counter (mine uses an HEF4060BT which is pin compatible with the 74HC4060 ic).

I didn't bother desoldering and lifting Pin 2. Instead I opted to simply cut the PCB trace to that pin instead. Much quicker!

FYI: the mod works because Pin 2 is the oscillator input, which *appears to get a half-wave rectified input from the AC 60Hz power input (* I have not reverse engineered the board, but that's my "gut feeling" based on the components around that pin). By cutting the oscillator input you are preventing the counter chip from counting - a pretty clever trick.

[deb1ie]

I have a Sunbeam heated throw/lap blanket with a 3-hour shutoff. Do you think this modification would be about the same as with the heating pad? How’s a girl supposed to keep her totally outdoor cat warm at night? She sleeps on the outdoor back porch at night, which is her choice, not mine.