Industrial Electronics Repair : PLST-BCT Swimming Pool / Spa DIN Rail Timer
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- Опубликовано: 28 авг 2024
- Here's a PLST-BCT industrial timer that is used in Swimming Pool and SPA applications. I was asked to look at this to see if I can repair it for a local business. They say that there are more of these units and similar items that they have which are faulty and that they were surprised there is anyone here who works on such items. This sort of kit is expensive to replace so let's see how easy it is to work on and whether this sort of work is profitable
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Thank you
Richard
I’m very happy to find this channel. With as many electronic channels as there are, 99% of them are a waste of time. Especially for beginners. Keep up the good work.
This is my favourite sort of video, you are very clear in explaining your thoughts and not afraid to say your first thought was wrong. Thanks for sharing your knowledge and taking the time to make these videos. I'm a hobbyist and learning loads from you.
50 Euro sounds fair enough. Customer said you're the only one that does these jobs so I guess there will be more business coming 😄Waiting for part 2
Surprised you're not using a capacitor ESR meter, saves an enormous amount of time especially as you can usually find dried out electros while still in circuit.
The one I've been using for the last 20 years is the "Silicon Chip Magazine ESR Meter Kit"
Beaut videos, Thanks.
Thank you very much for recording and posting this!
Even if the electrolytic caps measure ok, I would still change them before changing the chip. These chips mostly fail because of bad electrolytic caps.
For starters: I love these videos of you giving a clear explanation on the tests you perform and the subsequent actions you take. The solder joints on the switch mode chip look a bit cracked, but perhaps I'm imagining things.
I like these types of videos. Both interesting and educational. I think that these industrial devices are really interesting. I'm at a transition point with my age and health. I need a new hip. So I am working on figuring out how my future will be. When I can get a new hip, I'll need to start working for a living again. I just take care of my father right now, who has bad health problems.
Make sure you have the right size of heat shrink tube in stock to re-wrap the PSU after repair.😉
Thanks for sharing all your knowledge, please keep it coming.
Hello
Every time I learn something new I give a thumb up you get one every video. Thanks.
I think the processor chip was a pretty standard 328P - the same as found in many Arduino Uno. Nice tip about using that inverting buffer on the outputs to protect the chip.
great video,... And for me I got to learn about some new parts, also sometimes when you don't know how something works you just have to slowly work through it and see if you can figure out how it works by examining all the parts.
I love all your videos and watch some of them over and over till I learn. As I’m trying to learn and diagnosing some stereos sometimes I get confused about what should be AC or DC voltage. Do you think you can do another learning video about how to find out what is what and where you should and shouldn’t find AC or DC? I’m sure I’m not the only beginner that gets confused by this. Thanks and keep them coming!! And happy holidays to you and your wife!
Just put some heat shrink on the pins of your test leads so that only 2mm stands out. That should suffice
A suggestion is to also change C5, if that is the capacitor on the Vdd pin of the switcher. Using a ceramic capacitor for that supply is not the best of designs.
"Using a ceramic capacitor for that supply is not the best of designs."
Why?
If this capacitor was faulty (open circuit or low capacitance) then it would cause the PSU not to start, Likewise if it was leaky or short circuit but I checked for that. In my experience these MLCC capacitors don't fail by low capacitance, though electrolytics often do, As it is an MLCC and not short or leaky I didn't investigate this further, but if a replacement IC does not fix it then I would change it as it could be breaking down when voltage is applied. Another possibility I didn't check for is a shorted turn in the transformer, though this is difficult to test for and would more likely cause the PSU to power cycle
@@d614gakadoug9 Generally (though not always) electrolytics provide a higher capacitive and energy density, equating to better stability over time. You mostly see aluminium electrolytic in these designs and the datasheet shows a polarised cap. Although MLCC have come a long way, they regularly break down due to heat, vibration, moisture and large spikes (as any laptop repairer will tell you). My suggestion of changing C5 is just my opinion, and in no way suggests that this is the cause of the issue.
@@ralphj4012
Aluminum electrolytic caps are vastly inferior to MLCCs in terms of ripple current handling and ESR. They have an in inherent wear-out mechanism and MLCCs do not. It is quite easy to get good-quality MLCC of sufficient capacitance for that position without resorting to the types that have horrendous negative voltage coefficient of capacitance.
It is very common these days for switchers operating at high frequency to be all-ceramic designs and reliability is excellent. Of course this switcher probably operates at less than 150 kHz, but in that position an MLCC is entirely adequate.
The aluminum output cap is the one most likely to fail.It is a flyback converter and they are _very_ hard on the output cap, imposing very high RMS ripple current in comparison with other topologies.
I have yet to see a video of someone replacing an SM ceramic capacitor in something using any semblance of a technique that is satisfactory for decent reliability. I've seen some absolutely abominable hacks "teaching" people how to do this stuff (Sorin at another "electronics repair" channel is such a hack).
@@ralphj4012 Ralph, I quite agree with you. As mentioned I was solely going by previous experience with MLCC but if it has failed in the way you suggest then it would cause this exact type of fault. I guess this is mostly down to repair methodology where one person would have changed the (MLCC) capacitor by default and the other wouldn't (but would have been much more suspicious of an electrolytic causing the same fault condition) and I don't really think there is a right or wrong approach here, it's more matter of personal preference how to approach any given fault. 🙂
Comment for the gods
Nice work...cheers!
Those bottom terminals are probably for capacitive proximity sensors possibly used for level control or something similar?? Just a guess!
You should check input pins of bridge rectifier, maybe I imagine something but right one (same side as positive opposite to it) seem to be in the air.
I double checked that this morning, all the soldered joints on the bridge rectifier are good
I would use a PCB holder .. one you’d use to assemble/install components on the board, so it would stay put (and not use your hands, holding it) while you’re testing and working on it.
+ sharp probes to avoid accidental slipping
@@MadaraUCHIHA-hy9xe I doubt I can find sharper probes than these. A PCB holder is a good idea actually if only to make it easier while recording videos. I'll order one.
I'm wondering how much damage I could do with a bench power supply attached where the power supply used to be attached while your waiting on parts?
I would think I might be able to check the rest of the circuit for problems this way but maybe that's a bad idea?
I also would have powered up the unit from a bench power supplier to check all is well before ordering replacement parts. 😁
Does the soldering on the AC input plug look suspect?
The area that says npn and pnp are jump rails
Can you post a bit more information about this topic. Thanks
@LearnElectronicsRepair To be perfectly honest, I don't really know much about it. Just that from what I can see in the video, it appears to be a series of pins with jumpers. The npn and pnp have indicators pointing at different rows of pins. It appears that the jumpers are currently on the npn pins. Again, I am not super knowledgeable here, but it seems that moving the jumpers would change the operation of the circuit. I could, of course, be completely wrong. I apologize if it turns out that I am.
In industrial engineering the sensors either output a voltage PNP or Sink a voltage NPN . To be usable on many different control cards and input sensors it is made user selectable. @@LearnElectronicsRepair
Hot ground… isn’t that common (com) pin 5 On-The-Go output?
Re working safe: "High Voltage comes without brains, so use your own"
If you move the jumpers it changes the settings
I‘m in bed with corona, that‘s why I have time to watch so many of your videos😇
And they are always great value👍
What about the 000 resistor? Could be open circuit there.
Hi. I double checked that this morning, firstly it is not actually a zero ohm resistors as I thought, its actually marked 1000 but the 1 is hard to see. That makes it 100 ohms (1 0 0 followed by zero added zeroes) and it reads correctly
That thing is a boxed arduino driving an ULN2003 and from there some outputs
I did buy some cheap pmics once from aliexpress and my 1st thought was why fake such a cheap chip
I bet it's a broken winding on the transformer.
The primary winding looked ok and also the aux winding. It's very difficult to test for a shorted turn unless you have a known good transformer to compare with so I stand by the decision it is time to try another IC, but also accept you could well be correct. Time will tell
Maybe a future project, building a simple ring tester to test transformers, using PCBWAY Richard. @@LearnElectronicsRepair
The unit price must be £100 so if you repair it for £50 it is a win win, only if it lasts half the life of a new one.
I showed the price in the video, it's €130
you could do withe some new test leads ,yours look very bendy and dangerous ,not up to fluke standards, I dont know how you work with them
Its the reverse, They can be quite expensive or hard to find and in fact I'll bet you he has them by choice. They are great forgetting into tight places and very sharp to make light work of any conformal coating or flux left by poor manufacture. Remember Mr Jackofalltrades proper tools for the job used by skilled people is the right way to do it, so if your not skilled or they make you uncomfortable you shouldn't use them , in fact I think Richard explained it early on.
obviously you dont do this kind of work@@andymouse
Correct ! I retired after 40 years it's just a hobby now.@@jackofalltrades3727
@@jackofalltrades3727 To be honest I do use these probes by choice. They were part of the Kaiweets KET05 probe kit
www.aliexpress.com/item/1005003727037642.html?af=ler2022 and they were not cheap. Well in fairness they were cheap as I received them as part of a free Christmas gift box last year from Kaiweets but you get my point. I always preferred sharp needle point meter probes and most types I tried would break after a month or two but these are really going strong after a year almost. I did comment on the safety (or not) of using them on high voltage circuits, and my reasoning regards that, in this video.
@@LearnElectronicsRepair "but you get my point" Pun intended :-)
The pricing is certainly tight for this kind of equipment. When the client can tax deduct the cost of equipment, the delta to a new one gets fairly small.
If more of them fail in the same place (as you suspect), then it could be a design fault (possibly cooling of the chip?) and he would be better off buying a different brand or type of timer.
On the low end of pricing, even if you know where the fault is, it will take at least half an hr to get everything opened, repaired, tested, closed, so you don‘t want to go below 25€ to make it worthwile.
So, not an easy one. No comparison to the transmodulator you repaired a year ago where the cost of replacement is 10 times higher.
Funnily enough my next repair job is another transmodulator 😉
50 euro's is fair enough, your not running a charity.