I have three of these PIR units in my house (UK), two have died in the past and I just replaced them, the latest failure and I found it difficult to buy another straight away, I searched on line for one to buy, and found this video by chance. I took mine to pieces and found it had exactly the same capacitor problem, two new ones from ebay (£5 for two sets of ten of them) and it works! Thank you so much.
Please keep on pumping more videos!! I also have an degree in Electrical Engineering but school doesn't teach Failure Analysis. I learned so much! thanks!
Our sporting club has upwards of 20 of these sensors ... there is always a faulty one somewhere... being council property we are not allowed to interfere with them ( rightly so ) As a temporary fix whilst waiting for contractor to replace the faulty unit, we give them a light couple of taps with a broom handle and they fire up, generally working for the entire game day .....until next training session Nice video and well presented
The fact that you pulsed it and it didn't lose any capacitance is super interesting.. maybe having the X cap closer to the heat source in some cases is beneficial? Drive off humidity? Unless its just humidity when manufactured and not after.
That thud you heard when you attempted to shock the capacitors was the LP12's internal safety dump relay, the impedance sense probably found something out of wack when it tried to initiate discharge and sent the energy through the dump circuit
Side note: I'm very familiar with the 12s internal workings, if you have any questions about the workings of your unit I'd be more than happy to help. I'd also recommend giving the service manual a thorough read, it's freely available online and whichever version you find will likely apply just fine
Interesting! I knew about the dump circuit and have heard it be switched in when you command a charge but then cancel it, but didn't know it could be switched in during the discharge but now I think about it, it makes sense it should. I have had a couple instances discharging into strange loads often with bad contact it gives the "ABNORMAL ENERGY DELIVERY" or "ENERGY NOT DELIVERED" messages, but can't remember what sound it made. Unfortunately I didn't record the screen of the LP12 but I did have another wide camera angle I used for the audio which happened to record the therapy cables jump a little from the magnetic field during the discharges and I can hear the 3 beeps after for the priority 3 tone so I think it probably did get the full or part of the 360 J. The _thud_ sound in the recording does sound different to the usual _click_ of discharging into 50 ohms, I can't remember what I did for the audio, I might have recorded it with a lapel mic, possibly very close to the LP12, but I can see in the edit I put a +24 dB gain on it otherwise you can't hear it, in the raw recording it's a very quiet _click_ sound. Next time I'll also record the discharge waveform with an oscilloscope current clamp and HV probe so I can show the real peak power the component is subjected to (18.5 kW figure is just for 50 ohms) and be confident it actually discharged properly in both phases. And thanks for the tips. I certainly would not be using it without having first read the operators manual and service manual (which are really good). This particular LP12 was damaged in shipping from it's annual calibration so was written off as a total loss, I got it and replaced the shattered LCD and repaired the ECG/SpO2 PCB. I've been meaning to make a video about the whole thing but haven't had the time. But I will eventually! And thanks for watching! I remember when I got the LP12 I watched quite a few videos about them including yours so cool to see you here.
@@WizardTim That's cool! I didn't know you came across those old vids. I also recently fixed up my 12 and got it calibrated and repaired and the software updated so it's just like new and made some new vids on it. And you'd be right in thinking some energy would make it even with an abnormal delivery message. I was messing around one time and zapped an apple, made a big spark along with the abnormal energy delivery message. Im more familiar with how the defibrillator reacts with hard paddles since it's more lenient on letting you discharge those into thin air or strange loads (where most of the time it'll just engage the dump relay). I'm more hesitant with using the therapy cable for experimenting because I want to keep it in good shape in case someone licks a power outlet wrong but luckily I have a couple of other units with cable that I can experiment with (though they are monophasic). If you want I can invite you to a small little med tech enthusiast discord I run, we have a good number of people who are knowledgeable in different tech for example I am the resident expert on LPs while another person knows more about Zolls. All the best!
I learned so much!!! Im so interested in learning about these type of failure modes. Where did you learn these skills from? Can you point me to where you get the Transient generator that you used for blowing up the caps?
Thanks! I learnt most of it from TH-cam videos just like this one from other people along with plenty of blogs and forums but also an electronics engineering degree at a university and also through my employment. The transient generator is actually a medical defibrillator, specifically a LIFEPAK 12 that I repaired which will be the focus of a future video (#20). But I must note that defibrillators are dangerous, don't play around with them unless you know what you're doing, the energy they store is lethal.
I have three of these PIR units in my house (UK), two have died in the past and I just replaced them, the latest failure and I found it difficult to buy another straight away, I searched on line for one to buy, and found this video by chance. I took mine to pieces and found it had exactly the same capacitor problem, two new ones from ebay (£5 for two sets of ten of them) and it works! Thank you so much.
Your video is truly captivating, and the topic you covered is highly thought-provoking.
Please keep on pumping more videos!! I also have an degree in Electrical Engineering but school doesn't teach Failure Analysis. I learned so much! thanks!
Another excellent video, it's great how you get to the root cause of why components fail and give us detailed reference photos at the end!
Our sporting club has upwards of 20 of these sensors ... there is always a faulty one somewhere... being council property we are not allowed to interfere with them ( rightly so )
As a temporary fix whilst waiting for contractor to replace the faulty unit, we give them a light couple of taps with a broom handle and they fire up, generally working for the entire game day .....until next training session
Nice video and well presented
These videos are equivalent to a pot of gold for pcb repairs
The fact that you pulsed it and it didn't lose any capacitance is super interesting.. maybe having the X cap closer to the heat source in some cases is beneficial? Drive off humidity? Unless its just humidity when manufactured and not after.
That thud you heard when you attempted to shock the capacitors was the LP12's internal safety dump relay, the impedance sense probably found something out of wack when it tried to initiate discharge and sent the energy through the dump circuit
Side note: I'm very familiar with the 12s internal workings, if you have any questions about the workings of your unit I'd be more than happy to help. I'd also recommend giving the service manual a thorough read, it's freely available online and whichever version you find will likely apply just fine
Interesting! I knew about the dump circuit and have heard it be switched in when you command a charge but then cancel it, but didn't know it could be switched in during the discharge but now I think about it, it makes sense it should. I have had a couple instances discharging into strange loads often with bad contact it gives the "ABNORMAL ENERGY DELIVERY" or "ENERGY NOT DELIVERED" messages, but can't remember what sound it made.
Unfortunately I didn't record the screen of the LP12 but I did have another wide camera angle I used for the audio which happened to record the therapy cables jump a little from the magnetic field during the discharges and I can hear the 3 beeps after for the priority 3 tone so I think it probably did get the full or part of the 360 J. The _thud_ sound in the recording does sound different to the usual _click_ of discharging into 50 ohms, I can't remember what I did for the audio, I might have recorded it with a lapel mic, possibly very close to the LP12, but I can see in the edit I put a +24 dB gain on it otherwise you can't hear it, in the raw recording it's a very quiet _click_ sound.
Next time I'll also record the discharge waveform with an oscilloscope current clamp and HV probe so I can show the real peak power the component is subjected to (18.5 kW figure is just for 50 ohms) and be confident it actually discharged properly in both phases.
And thanks for the tips. I certainly would not be using it without having first read the operators manual and service manual (which are really good). This particular LP12 was damaged in shipping from it's annual calibration so was written off as a total loss, I got it and replaced the shattered LCD and repaired the ECG/SpO2 PCB. I've been meaning to make a video about the whole thing but haven't had the time. But I will eventually!
And thanks for watching! I remember when I got the LP12 I watched quite a few videos about them including yours so cool to see you here.
@@WizardTim That's cool! I didn't know you came across those old vids. I also recently fixed up my 12 and got it calibrated and repaired and the software updated so it's just like new and made some new vids on it.
And you'd be right in thinking some energy would make it even with an abnormal delivery message. I was messing around one time and zapped an apple, made a big spark along with the abnormal energy delivery message.
Im more familiar with how the defibrillator reacts with hard paddles since it's more lenient on letting you discharge those into thin air or strange loads (where most of the time it'll just engage the dump relay). I'm more hesitant with using the therapy cable for experimenting because I want to keep it in good shape in case someone licks a power outlet wrong but luckily I have a couple of other units with cable that I can experiment with (though they are monophasic).
If you want I can invite you to a small little med tech enthusiast discord I run, we have a good number of people who are knowledgeable in different tech for example I am the resident expert on LPs while another person knows more about Zolls.
All the best!
I learned so much!!! Im so interested in learning about these type of failure modes. Where did you learn these skills from? Can you point me to where you get the Transient generator that you used for blowing up the caps?
Thanks! I learnt most of it from TH-cam videos just like this one from other people along with plenty of blogs and forums but also an electronics engineering degree at a university and also through my employment. The transient generator is actually a medical defibrillator, specifically a LIFEPAK 12 that I repaired which will be the focus of a future video (#20). But I must note that defibrillators are dangerous, don't play around with them unless you know what you're doing, the energy they store is lethal.