Biddeford Electric Blanket Troubleshoot / Repair / Internals
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- čas přidán 4. 05. 2019
- A thorough look at the Biddeford series TC12B0-D electric blanket controller, including blanket testing, circuit internals, troubleshooting and repair. This model has a 4-wire/4-prong blanket connector and is also sold under the Sealy, Cannon (76PA) and "Living Quarters" brands.
A 2015 board is examined and serviced and a 2010 board is shown.
The schematics mentioned in the video are here:
youtube.wardco.com/Biddeford_T...
The expired 1999 patent that covers this controller is here: patents.google.com/patent/US5...
The older TC15B2 is similar.
Here is the gray-market 1.5uf CL21 cap I just bought to replace C1 off ebay
www.ebay.com/itm/20Pcs-Metall... - Věda a technologie
This is perhaps the best electric blanket video on CZcams! More than I could have expected. Electric blanket nerd!
You have excellent taste. Thanks!
This video is littered with many comedic gems. He is so funny! And he says it so nonchalantly. “So naturally I ignored her.” (Doing this modification could potentially kill you, so then he says...) “So if you lack the necessary skills to do this kind of stuff, you should have a few drinks first” Sir you have such a great sense of humor! But please be nicer to your wife if you weren’t joking lol, Appreciation goes a long way! I appreciated stumbling on your video!
Thank you, PI.
He had me giggling too. So hard to find good humor these days!
I know this is 5 yrs old, but an awesome vid, and your sense of humor is fabulous!! Thanks for the info, hope I can fix my 3rd controller which is dead!!
That joke about having a few drinks if you were unskilled and intimidated dealing with a mains powered board cracked me up (and the assorted sacrifices for your wife's electric blanket travails).
I was watching with half an idea that I could juice my 100w electric 'throw' toward delicious, life-threatening heat. Petrol + lighter would be too odorsome, not to mention fleeting.
Good grief, I watched about 40 min on this. Good job sir.
Thanks SortBiker! Appreciate the kind words. It never occurred to me to set my wife's half of the bed on fire, but now that you've suggested it...
No...no...
I was having problems with my blanket at well. I put the controller on the other side of the bed and it heated it up fine. I then took the other controller and put it on the other side and it heated fine which lead me to believe it was the controller. Then I figured it wasn't getting a good connection so I out little pieces of aluminum foil in the tiny holes in the cord that plugs into the blanket and now it works. Nice and warm.
OK, first off, I wish I had paid more attention in French class years ago, because pretty much everything you said was French to me. I THOUGHT by watching your video, I'd be able to fix my electric blanket. I was wrong...so I guess I'll just buy a controller off EB, or a brand new blanket from a box store. Secondly, I did watch the entire video, including the out takes, cause you had me laughing from the beginning. So kudos for your sense of humor, but more so for your electronic knowledge. Very impressive. I know now that an electric blanket repair business isn't going to be my second career. Thanks for the video anyway. :-)
Thanks Pete! I hear you. Who could have guessed that spending hours repairing a $15 piece of disposable consumer equipment would not to be the glamorous and financially rewarding career we had hoped! It all seemed so promising at the beginning...
@@WardCo 😂😆
Thank you so much for making this video and breaking down this blanket/board, it has helped me repair and diagnose 2 separate blankets!!! I hate throwing away repairable equipment but I lack the formal education on how the electronics actually work, But I can at-least solder well xD Thanks again!
Thanks for the kind words, Husky. Appreciated.
It's going on almost two years since this was posted but my Biddeford heated mattress pad has been acting up so I figured I'd see whether this video would help me. Holy moly! I wish I'd paid closer attention during the Circuits course I took back in college. Man, you must be an E.E. who designs circuits to know what all this stuff is. Actually, most of these components probably hadn't even been invented back when I was in college. Anyway, I found that the controller for my mattress pad is really quite similar to the one for the blanket. I may have even found the problem as my mattress pad seems to be working okay again. Enjoyed your humor. I even watched one of your other videos about fixing an electric bottle opener. Glad to see someone else believes in repairing stuff rather than just pitching it out. My wife even enjoyed watching that video and she's not at all mechanically-oriented.
Heh. That's great Greg. Thanks for the kind words. Very much appreciated.
This is the best, easiest to understand video! Thanks for explaining so well. I'll let you know how my blanket turns out.
How did it turn out?
This video was *definitely* not too long for me - I was looking for exactly this much detail. I wanted to understand how they worked and give myself a starting point to make a (much better) controller of my own, and now I believe I do. Big thanks for this!
Oh - I also stumbled over the word myself, until ... aha! body parts! thigh, wrist, or ???
Finally!! A comprehensive explanation of electric blankets! Great video. After plugging in 3 controllers to a defective blanket, I finally figured out the heater and sensor wires are shorted together. Your video is the first one to identify the pins on the blanket. Now to order replacement fusible links to get the controllers working again. Thumbs up!
Thanks Randy!
Enjoyed listening to the video eating ice cream with my dog on our cold twin blanket, hoping the E turned into a number. When I got done I pulled the cord out of the blanket, turned it around and plugged it back in. It works fine now. At least now I know how to repair it and my year of Army electronics training 50 years ago will come in handy, after retirement. As it is now, at my hourly rate I could have bought two new blankets for the length of the video. I'm surprised your wife did not replace her controller with yours and not even mention it. My wife bought this blanket on sale at least 10 years ago, and this was its second night of use. Thanks for the video!!
Thanks John. (Please don't give my wife any ideas!)
Your video is beyond my knowledge level, but much appreciated.
Thanks! Saved me a bunch of time troubleshooting my daughter's blanket controller. My controller is a little newer with a mix of surface mount and through hole components, but same basic idea. In my case it was the thermal link between the two resistors. Have a few on order and will replace the failed one and then do some testing for a bit before I return it to service just to make sure there isn't some other root cause that is causing the thermal link to fail.
The thermal protection device failed again after a few day's use. After stumbling on a video of Sunbeam blankets burning up I decided not to repair again. As a test, I connected my Variac to the blanket and turned it on with voltage set to 120 VAC to simulate what might happen if the controller failed in the stuck on position. Because some people leave their blankets folded at the end of the bed, I folded the blanket up and left it sitting in a safe spot in my driveway. Was in flames in less than 30 minutes . . .
@@RideGasGas WOW! Thanks for sharing!
Great video, I've had Biddeford blankets for a long time and have replaced many controllers. Your video tells me how to troubleshoot/repair which I'm going to try. Tks!
Hahaha! One of the hidden gems of CZcams right here. It helped me fix my own electric blanket controller and made me laugh while learning about how to do it. Thanks so much for making this video!
Thank you J
Thank you for a very comprehensive video. In my cat on of the 5v Zeners failed closed and pull the rail to zero. But your walkthrough of the circuit saved me hours.
I'm Liking and subscribing
Thank you, sir. Another fellow here in the comments had zener failure too -- and yes, when they go, they like to short. I just wonder what causes this? Sure seems like the babies are sensitive to power conditions -- or maybe the stress of cycling the load all the time has some bad effects.
I enjoyed watching your video, many laughs too thanks. I have a pair of those Sunbeam dual-control blankets. Both do not give off codes or "E's" but there is little to no heat coming out of them.
Great video. Thank you for taking the time to create this very informative video so all of us married guys can sleep peacefully again 😄👍.
Changed out that capacitor and my blanket lives again!
Ha! That's great to hear. Cheers.
Ward, Great video. Believe my problem is C1, however will replace C2 as well. What a great bit of revers engineering.
I have a Sunbeam 6 zone unit. Wasn't working well last year and this year not working at all. Thanks to your video was able to understand how these things work. In my case it appears from a resistance test both sense wires appear open. All 6 Heating wires are around 12 ohms. Can only assume that the "infinite resistance" tricks the unit to turn the outputs off. Don't have a isolation transformer handy so haven't scoped the triacs but they are all showing mains output on a multimeter which is odd?, Duty cycle I suppose as the unit draws about 10-20 watts when the label shows 180watts x 2 Only option I suppose is to open up the pad and see if I can repair the breaks, or perhaps first step is to solder a 1K resistor across the sense wires and see what it does.
This was so enjoyable to watch!
Nicely explained,
You saved me lots of time.
Thank you!
Thank you so much for all your time and effort in making this video. It was super helpful to have the circuits explained. I have the 2010 model but it's slightly different than yours. I think you were exactly right about the triac needing a better heat sink, and that's why they changed the design. The printed circuit on mine looks kind of discolored and rusty near the triac and smells burnt. At least now I know how it works and what the problem is. I enjoyed the humor as well. Great video!
Thanks for the kind words J.
Yes i watched it thank you! Trying to diagnose the frigid old woman issue.
Generally not as easy to solve as replacing a capacitor...
VERY helpful video. So I have a much newer controller than either one of yours. No date but it is all SMD. Biddeford wanted me to pay for return shipping for any warranty. Then I noticed that the schematic for these newer units seem pretty close to yours. My symptom was that it would only give me the power on dot and nothing else (and it also seemed a bit too dim). It also did not rapidly cycle through the digits when first plugged in. To make a long story short I found that the 9.1volt Z1 was shorted. Replacing it fixed the problem. My question is what caused it to short? I would not really worry about it since it is fixed except that have TWO controllers (on two different blankets) with the EXACT same problem!!! Thoughts?
I loved your video, even though it was way long. My wife's electric blanket displays "E" after it is in use for a while, but only if it is set above 6. Setting to 8 causes it to fail after a while. I'm not sure why that happens. Would ripple in the 5 volt supply affect the processor commanding higher settings? The mystery awaits me. I have a VOM like yours but I need a scope to troubleshoot my electric blanket. Hopefully, I'll be able to fix it without a scope. I think it is commendable that you have taken so much effort and time to investigate this problem. I think you must be retired with some extra time on your hands. Well, you have done good service to help many people with similar problems with this electric blanket. Keep up the good work at making the world a better place. As a side note, from my experience, never expect an electrolytic cap to be what it is marked. It's a blessing if it is high than rated. And never expect an electrolytic cap to filter out high-frequency noise, That's what the mylar cap is for as wired parallel to the electrolytic. Thanks again for this great video! Keep up the good work!!!
Thanks for taking the time to write these kind words, Carl and thanks for the tips. I was NOT retired when I made this, but I am now, and think I have another interesting (too long!) video in the works on another bit of tech I've recently become obsessive about. But at this point I'm not sure if I'm going to beat it, or if it is going to beat me! We'll see...stay tuned.
Funniest video I ever saw. Like my favorite teacher. Thanks
Great video. Thanks! The, have a few drinks thing was great!
Great laymen term video.
Great video. My problem is, the Sunbeam blankets always go high-resistance so instead of 150W they always default down to 16W. It’s not a loose connector connection but the element goes to a stable high resistance measured at the blanket connector. Have not figured out how you can actually fix the element wire…
Great video, thank you. I have a strange failure and hope that you might have some advice for this novice. Both of our controllers seemed to fail while in summer storage, but maybe they died right before taking the blanket off. When we put the blanket back on neither controller would power up. I opened one controller and the thermal fuse is blown/open, the resistors look fine and test good, and the blanket's heating elements both show a bit over 120 ohms so they appear to be good. I temporarily bypassed the fuse and ran the blanket on high for about a minute and it's working. Should I assume it was a Fluke and replace the fuse? Maybe replace it with a piece of 10ga. wire so we're guaranteed to stay extra warm?
I assume the other controller has the same problem but I can't reach the power plug to disconnect it. I've had enough drinks to feel qualified to work on it, but one too many to safely open it live.
Thank you for your video. I have fixed two devices.
My board is a 2012 and looks nothing like yours. Neither of my controllers power on when plugged in. There are no areas that looked scorched and there seems to be some type of internal glass fuse that looks intact as well. I guess I will call their customer service hotline because I will never figure this one out! Lol
Still a great and informative video.
Very well done. Thank you.
Great video- nicely explained whole operation of the heated blanket! I was able to find that one of my blankets is damaged and it caused two controllers to be damaged as well. Fixed thermal fuse that was blown but now I see E on the display and I can’t find anything else wrong. Any other ideas?
Thanks Snehal. Hard to diagnose from afar. Do check the DC voltage level and quality, and the input clock to the CPU though.
@WardCo how can I make this controller less bight that would be a huge value add! Also awesome find on the Preheat + 2 as I had no idea what that did i thought it was max temp
Thanks, I found the problem. The temperature fuse was open. Price for a new component $3.00
Thanks got it fixed
You the man 👍
Excellent work, thanks for sharing! Surely this will help someone down the line.
So the current from 120VAC source through the heating element section would be about 1(one) Ampere (1Amp = 120V/112 Ohms), thus the element would be capable of generating about 120 Watts (120W= 1Amp x 120V) of power each side.
I measured my (new) blanket heating element at about 90 Ohms, FWIW. That would make mine a 160 Watt element.
My sunbeam control provides 24v to the blanket. I can't imagine using one with 120v, it would be unpleasant to wake up to a fault.
@@acoustic4037 if you're sleeping in a wet bed perhaps? Been using 120v blankets on lamp timers for 60 years and no probs yet. I hear the new blankets are unreliable and shut themselves off after a short period of time, must be reset manually once you wake up from being cold?
Anyway, the power source for electric blankets in the us is 120vac, not sure where your isolated 24vdc is coming from, a gfi safety device or isolation transformer are options.
Your CZcams handle... lmao
i miss the old "dumb" technology , where you just had a toggle switch for on/off . had my old one on a timer , came home each night to a warm bed . i have to physically turn the new one on each night , and if the power blinks , if i roll over the wrong way , or if the blanket just decides i've slept long enough , it quits . "naturally , i ignored her" . now that you mention it , i seem to remember being married once .
Heh. Yeah. I'm not sure all this tech buys us much that is better than an old bi-metal coil clicking on and off all night, but...here we are in the future.
Hi i tested the thermal fuse and it was good and also checked 240V on the output side of the fuse and it was there. All diodes test good- no other electronics on this one, but i have 4 wires from the blanket and no matter what combination i try i get at min is a few thousand ohms?? does that mean the coils in the blanket have had it as i noticed the little light sometimes come on and not although the blanket did heat , now i get nothing on any setting and no light or warmth on blanket.
Thanks
Ok, someone else solved the "JP6" issue for me.. I showed this to another engineer, and he quickly discovered your mistake in reverse engineering the schematic. When you flipped the board over, you reversed the positions of R26 and JP6 when you wrote on the back of the board to label them which are above and below each other. The jumper feeds the gate, and the resistor is tied to ground.
I think it would be good if you could take the time to fix your schematic, and the labeling on the back of the PCB side.
great video explain how it works. just a curious question, when you connect your Osco scope to the board, how do you avoid short the oscoscope to the ground. I had used my scope before on main circuit and accidently blow mine. it seems your scope can manage it. any suggestion?
Hi Ted. I have the blanket controller on an isolation transformer. (The other way to do it is with an expensive differential probe.)
@@WardCo thx, that explains how you make it. Smart idea
I have a newer model, TC11W1, that has surface mount components, but the circuit design looks to be the same.
I noticed the link to your schematic does not work. Are you able to update the link?
Still working AFAIKT
Hi. I enjoyed your video. Thanks! Someone gave me one of these to fix. LED doesn't come on (other than little dot lower right) The blanket is my problem I think. Your test you showed around 120 ohms across H1-H2 and 1K ohm across S1-S2. I get 80 ohms between H1-H2. But S1-S2 is open. Also, I get around 1 Kohm across H1-S1 or H2-S1. Sound like the wiring in the blanket is the trouble? Thanks!
If S1-S2 is open, yeah, the blanket is broken.
Still a better story than Twilight
First off, thank you for such a detailed description of your investigation. And as others have said, for the enjoyable commentary and how you presented your discoveries. I'm a retired electronics mfg. manager with "some" troubleshooting skills. Just enough to get me in trouble, lol! The issue with my controller is that it appears to be that when I initially turn it on and it is at the "1" setting, it seems to heat up very high. But occasionally it doesn't get as hot. We were going to swap controllers to opposite sides of the bed to test to see if maybe it was the blanket but my gf doesn't want to give up her controller in case it might get damaged. Any thoughts on what might cause this? Thanks in advance.
Intermittent problems are the worst! If it gets too hot then we're talking trouble with the temp control feedback system, so I start to worry about a fault in the sensing wire in the blanket or a loose connection for same on the main board. In theory, the LM comparator IC or the transistor that switches the heat on and off could be faulty, but that seems farther fetched. That said, if you can pass the multimeter checks at the start of the video, I'd feel comfortable swapping controllers to help diagnose. Good luck.
@@WardCo Thank you! I will check as you suggested. Happy Holidays!
Well, the resistance checks show the blanket is ok. I took the controller apart and the board is all smd and has no date. I wanted to post a picture but I don't see that option. There does not appear to be any obvious issues with the board. I'm not sure where to go from here.
My resistors r43 and r44 burned out. Can you please tell me the name or code of the resistors to buy? What is the white resistor between r43 and r44? Thank you.
I have watched your video several times, plus other blanket repair videos on CZcams. No manufacturer seems to have a decent transformer-based power supply for the logic portion of the circuit, while the heating loop / ac portion seems to be simple, robust, and not prone to component failure. I wonder whether the reliability of all these blankets could be greatly enhanced with a good logic level power supply and optocoupled triac control. Of course a reliable blanket controller might be slightly more expensive and would cut the market for replacements. Call me a cynic.
Yeah, you hit the nail on the head -- these things are heavily "value engineered" -- that is to say cheap!
should have shown how to test the controller with the DMM and off the blanket. thank you.
I have that same control unit and I lost it so I bought one off eBay and it's just E2 all I can get out of it but anyway could I put any Biddeford 4-prong control module in my blanket like one of the other ones that has a knob and numbers between one and 10 stead of this digital display kind?
HI Randy.I don't know. Though I will say most of the stuff the microprocessor does in the digital units can be done with feedback circuits and bi-metal thermostats -- heck, that's all we had in the 60s, 70s, and 80s. But you'd lose the deadman timer. I just don't know if different resistance levels are used in a blanket meant for a digital control vs one meant for analog control. There might well be, in which case an analog unit would not work. Sorry. Never tried it. Don't know.
I have had one for years now and never understood something, is the number on the controller a timer or a heat setting?
A heat setting (or "E" for error). The 2 timers (debounce and deadman) have no UI at all.
You didn't say what the problem was with the controller. Was it not powering on or powers on and no heat? I have the TC12B0-D 2012.9.12 board and it does not turn on at all; no display. I am about to get the caps from your ebay link but want to confirm that the cap may be responsible for the no power condition. Also, when a cap goes bad, does it give off an electrical burning smell? I received my replacement controller from ebay this afternoon and within 20 mins of operation, it quit working with the same electrical burn smell. Sending that one back and will try to fix my first one. Thanks.
Check for continuity across the (white) thermal fuse. If it goes, there will be a burning smell from the two resistors on each side of it. Burn marks likely on the resistors too. If a 2nd controller went bad, you may have a (possibly intermittent) wiring fault in the blanket itself. Be careful. (You can get replacement thermal fuses on ebay, but it does no good replacing them if the blanket is just going to fry the next one.)
I don't think it is your caps, but you can use the schematic I made to trace the power through. In my case, the controller would power on, but the display would flicker, not respond to buttons, and finally just showed "E" all the time. It was getting power, but really noisy power with a ton of ripple on it.
@@WardCo Thanks for the prompt replay. I checked the resistance on the 4 pins of the blanket and they're all within the values as you measured on yours. No shorts between outer and inner pins. Next, checked the thermal fuse with the adjacent resistors and you definitely called it. The resistors were discolored and had the burn smell. So I plan to replace the thermal fuse and resistors. The resistors are 10 ohms right? (brn/blk/blk/gld). The fuse is labeled 125/250V N02E. I did a cursory search and nothing comes up with that nomenclature. Any ideas on a suitable fuse replacement? I had a year of electronics in college but was ages ago. Thanks again.
edit: I just noticed the resistors on your board is of the 200 ohms variety while mine is 10 ohms. Wondering if I should change to 200 ohms?
Yeah, and yet another controller blew. That's why I wonder if you have a fault that is intermittent or thermal. (That kind of situation really sucks.)
Hi Ward....would you please comment on this? My controller will not power up at all. Last night I set it on high, came back later and it was off and will not re-fire. I checked all the resistance and continuity in the blanket and it seems fine. I moved it around in case of an intermittent short but it followed your parameters except the heating wire Resistance was around .955 (should be fine.)I checked the thermal fuse and it has no continuity, one resistor appears slightly burned but both measure around 500 ohms. I checked your video where you briefly mention what would cause this fuse to fail but could use some more specificity as everything appears ok. the main fuse still has continuity. BTW, my control board looks different from both of those but similar in some ways....where is the date located? Thanks....Greg
Hi Greg. Sorry for the delay responding. Thanksgiving fun!
Seems like you are doing everything right, so now we turn our attention to the cord itself and ohm it out with the multimeter while flexing it to see if it has any problems (and check the solder connections where it attaches to the circuit board). If that all looks good, then we need to check the "T2_GATE" components in my schematic: T2, D5, maybe R29. If all *that* looks good, we may have a problem with the LM393 itself.
But, of course, I'm not an expert, even though I play one on CZcams. You're a "sample size of one" for me -- though enough people are looking at this now we might get some consensus on typical problems/solutions going. But, in the meantime, like you, I would really like to find a fault in the blanket or connecting wire before I go poking around on specific components! (And what made THEM fail?) Of course, you can always get a few thermal fuses on eBay and just "go for it" but, like you, I'm not terribly comfortable with that.
The date is silk-screened on the lower right corner of the 2 boards I have looked at.
Both of my controllers won't power up at all either. Did you figure anything out?
Pins 1 and 4 are 75 ohm is that normal the sensing matched
Good work! Well done!!! Thanks!!!!!
Do you have the schematic for this controller? Would make it a lot easier for me to fix
My reverse-engineered one is linked in the description.
@@WardCo Thanks, i missed that!! Looks like mine has a open thermal fuse so i need to track down what caused that. It's funny, though, this thing really is an exercise in making something as CHEAP as possible. Not even a voltage regulator to be seen! I have the 2010 version PCB and was honestly sort of surprised to find a full-fledged microcontroller because these guys obviously don't know about button debouncing. I have to hit my power switch 4-5 times or else it snaps back on. Would have taken just a few extra lines of code (which is free!) to properly debounce that switch!
Great video. On my controller the resistor on R20 is burned up. Its burnt so bad I can't read the value. I was looking at the video and I read a 5 band resistor as Green, Brown?,Red, Blue? and Brown. Does that seem correct?
Well, this is interesting. On my 2010 unit (which I keep meaning to sell on eBay for $10 or something) I have a orange-black-black resistor which is 30 ohms, and measures such, so I suspect that's the right number But, you're right, on the video my later unitooks like brown black brown (tolerance) green, which is 10 ohms (and my schematic doesn't even seem to have D9 ?!) Sorry I can't be more help with this.
Yeah, I looked at it again this morning and the 2010 board is wired differently. I'd need to open up one of the working units on my bed to tell you what is in the video, which is a PITA, but it ain't 30.
@@WardCo i got another working controller and opened it up. R20 looks like Brown, Black, Brown, Gold.... 100ohm 5%??
If it helps anybody else: I replace the resistor in R20 with a 100 ohm 5% 1/2watt resistor. My controller is working again....... thanks once again for the video it was extremely helpful.....
Where do you buy new fuses, etc. for Biddeford contollers?
Mouser, Digikey, eBay...
@@WardCo Thanks. What exactly are these termed in a search--Mouser, for example, has a million fuses.
Mine stopped working tonight. It won't power on and R23 looks burned up. I wouldn't have a clue on how to figure out its value.
The color codes in the video seem to be green-black-blue, which would be 50 meg ohms. My schematic has a 507 ohm notation, which I figure is a mistake. That goes out to the sense loop, so check your blanket wiring. Don't think it would stop the processor from running, but firmware may be deciding to shut things down when the sense loop doesn't check out -- or there may be other damage. :(
Mine is a beddenford pod 2 and it's got a blown fuse. How do you remove it.?
I can't speak to your specific model, but generally it has to be desoldered to be removed. I'll bet there lots of CZcams videos on the different ways to desolder stuff! Good luck.
I got one for Christmas and it hasn’t turned on yet and I’m very disappointed
Mine has auto off i was wondering why it quit working
🤣 you're hilarious
Thanks for the entertaining
Video
Thks & you have a PhD in Electric Blankets
Mine died and smelt burnt no longer will power on what do I do to fix it?
Well, there might be a video nearby on the topic. :)
I'd take a look at the thermal fuse.
All you have to do is call the company and they will send you one free.
Doh!
Seriously?!
That's because she didn't shove the power cable in the bottom
Don't you be making fun of where my wife puts her "power cable" -- or whatever the kids are calling it nowadays....
I measured the resistance between 1 & 4 on my blanket and saw 238 ohms. I then measured the resistance between 2& 3 and read 976 ohms. I then set my multimeter to the lowest ohm setting and measured between 1&2 and 3&4 and I got a reading that has a 1 to the far left and a '.' which I assume to mean open circuit.
Does this indicate that the internals of the blanket itself are ok?
This is a blanket made for 220-240V being used in a 230V system if that matters.
Voltage doesn't matter.
You resistance readings seem plausible. I don't know if I explained this well enough but the heating wire (1&4) is covered with an insulation that melts at a fairly low temperature and the thin sensing loop (2&4) is wrapped around that. The idea is that if the heating wire develops any hot spots, it will melt the insulation and short to the sensing loop and the controller will shut everything down.
I just looked at the 3 multimeters I have here. 2 of them show "OL" for open circuit ("overflow'), BUT, my old BK Precision from the 1980s shows "1." just like yours ("infinite"?) So I think your blanket wiring is OK.
@@WardCo Ok great. I've moved on to test the output voltage on the controller for my blanket (a Homefront/Osily/Mylek Choclate Heated Throw btw). I put the probes on 1 & 4 and then set my multimeter to measure DC voltage. Afterwards I turned on my controller and measured the voltage at settings 0-9. At all settings the voltage came out the exact same, which was 2V.
Should the output voltage vary based on the settings or does it stay the same? Or should a different value like current be varying here?
@@DB5tothehive If you are measuring at the female plug at the end of the 4 wire cord coming out of the controller, the CPU won't power up the circuit unless 2 & 4 have continuity and are showing a resistance in the sense wire range. The only easy way to measure this (without some kind of pass-through/breakout lash-up where the cord connects to the blanket) is to open the controller case and measure the connections on the circuit board directly -- but be careful, obviously. All the controller settings do is vary the duty cycle of the heating element on 1+4 as shown on the scope in the video. Also, you want to be measuring AC voltage on 1+4, not DC. I can't remember if I ever measured the voltage on 2+4, it is likely not significant, just enough to get a resistance reference value for the comparator/CPU.
How would you go about repairing the controller, if a dog chewed thru the wires and sort of blew it up. This is the order of what happened I believe: The blanket wires made a little pop sound, saw some minimal smoke, and there is some black on the wires. Seems the 2 sets of incoming wires must have touched, (DUH). The saliva from the dog may have made it worse, as must of us know water is not good with electricity -- the dog did not know this at the time, but I think he does now. I spliced the wires back together, but the controller will not come on -- nothing -- it is dead (the controller, not the dog). What sequence would you suggest to fix it? Change the fuse? What else? I am asking everyone who reads this to please not report me to the Human Society; I have enough problems as it is. Plus the dog does not seem to be permanently damaged; except he will not come within 3 feet of the surge protector or any other electrical wires now. One positive from all of this: if I get the blanket working, I don't believe this same problem will ever occur again. Any and all help is appreciated. Thanks
Ouch! Yeah, check the blanket wires as shown at the start of the video (to be sure the blanket itself survived ok), then open the controller up and beep out the thermal fuse with a multimeter to see if has opened. If so, it should be replaced, not bypassed. If not, it gets more tricky as you kind of have to chase the power through the right side of the board, but you can work backward from the rectifier diodes. The blue MOV may also be kaput. You can take it out and see if makes it come to life -- should run without it -- if it does, it should be replaced. Be careful, and if it gets to be too much, there are lots of controllers on eBay for not much money, and one commenter here has said the Biddeford sometimes sends new ones out for free with a phone call.
@@WardCo
Blanket should be fine, as he didn't get his teeth on it -- just the cord. I'll check the fuse and and thank you so much for the quick response.
@@AA-bj5rh Okay, as long as he didn't chomp on the 4-wire cable going to the blanket.
Riveting.
You talked about everything but the actual capacitor and how you got it and where you can get one how to test it how does it work you didn't know that very boring some good information but very boring but didn't tell me how to test the capacitor or where I can get one or anything else thanks
Well, the description above has information about the capacitor (though I expect the eBay listing has long expired). The ripple on the power rail was enough to determine it had failed, but there are lots of stand-alone capacitor checkers out there. It's always a judgement call to decide how tutorial to go in these things. I figured any one up for wading through this would already understand what a capacitor does generally and how it smooths the "pulsing" of rectified AC by providing a supporting charge when the AC waveform is crossing zero.
I just brought the blanket and never worked
Did you say... If you lack the skills to do any of this stuff, then you should definitely have a few drinks first? ROFL AS IF that would help gain the skills to do this ?? Literally after saying it could potentially kill you! Which I strongly disagree with lol doubt it'd kill you...
She broke her side so she could cuddle with you
This blanket sucks ??
For starters, it is pronounced "THY-rister", not "try"resistor or whatever. More properly, it is an SCR (Silicon Controlled Rectifier)
Secondly, Your comments at 17:27 is INCORRECT - you don't "throw open" the SCR to get it to draw tons of current to heat up the resistors.
Thirdly, pin 8 of the 393 compactor is V+ (supply), and so "probing it" with a high impedance scope probe isn't going to "load" it, so you should correct that.
Lastly, you show JP 6 in your schematic pulling the gate line of the SCR to ground, so you would never-ever be able to develop a gate charge on the SCR to get it to conduct. You need to find the correct layout and correct that.
Thanks for the corrections Steve.
@@WardCo No problem. I recently blew up 3 controllers in the last month, and thus why I am diving into this issue.
In my case, I am a Ham radio person (Call sign: W7SJ), and I frequently run 1,500 Watts, and so I'm wondering if I am getting RF (aka RFI) into the blanket, and firing the SCR. Remember, a blanket spread out on the bed full of wires is a perfect antenna.
So I wonder if all these people (you, me, and all the others here on CZcams making video's about this) may be getting subjected to RF fields, and RFI. Heck, even a GSM cell phone (or 2-way radio) can put out enough RFI to affect delicate electronics like this,
I'd really like to figure out what is going on here, or at least the designers intent here.
Anyways, I really appreciate you taking the time to reverse engineer this and draw the schematic and post it.
However, and as stated in my previous, I'm concerned about "JP6". As drawn, there's no way for the SCR to ever fire, since any signal from the LM393 is grounded out. I wonder if you could re-visit JP 6 some day if you ever decide to open the unit back up.
Steve
Electric blankets are unhealthy
Uh huh. And Smart Meters and cell phones cause cancer. Carry on.