Re: LG Washer/Dryer Power Fail
Oh yes redwire, you're right - I misidentified the ES3 part as a Shottky when it is in fact a fast Silicon switching diode as you say. The App note in the datasheet for a Multiple Output, 60 W, 185-265 VAC Input Power Supply uses fast Silicon diodes in all the higher voltage outputs so I figured it would be OK.
Unfortunately the LG PSU circuit only gets feedback from the 16.5V rail so the loading from the dryer fan motor leaves it with a poorly regulated voltage. With no load it puts out 23.5V dropping to 19.5V when the fan...
AdrianM
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Last Activity: 01-15-2023, 04:03 PM
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Re: LG Washer/Dryer Power Fail
Topic Update: Well, after 2+ years of continued use, the machine died in the middle of a drying cycle on Monday. My immediate thought was that at least I had bought a decent amount of extra time - it's now 8 years old and it wouldn't be so bad if it was finally time to buy a new one. But...
Curiosity got me to have a look to see what failed this time. The fact that it went completely dead (no panel lights or response whatsoever) hinted at PSU again. Fuses all OK? Check. 240V on PSU input? Check. 12V/22V on the output? Nope.
...Leave a comment:
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Re: LG Washer/Dryer Power Fail
These parts seem to have rather high on-resistances in general so it feels right to take this opportunity to waste a little less power.
But yes, I must admit to being curious myself about a like-for-like replacement however the repeated tear-downs and re-building were beginning to wear both me and the board connectors down. I strongly suspect a direct swap would yield the same result but I did actually buy a new TOP246 as well as the TOP248. When I get a chance I therefore plan to breadboard a small test circuit following...Leave a comment:
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Re: LG Washer/Dryer Power Fail
D243 [I]was [/I]a Silicon but is now a Schottky. I finally extracted the TOP246Y:
And replaced it with a TOP248Y plus 12K resistor in series with X pin to maintain the current limit (plus a little bit):
So now with the Fan running, after 30 minutes it's only getting to 47C and not tripping the thermal shutdown anymore:
I'm coming around to the notion that the dryer fan bearings are worn and putting extra load on the PSU. When I monitor the supply rails with and without the fan running...Leave a comment:
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Re: Rowenta TP 01 toaster repair
We can send spacecraft out past Pluto, study sub-atomic particles, peer at anything inside the human body with MRI - yet I've never come across a device that will automatically and repeatably toast bread.
Timer based toasters give different results depending on whether operated from cold or loaded with the fourth batch. Bimetallic sensing compensates up to a point but over-compensation is a problem when attempting to get a light toast in my experience.
Having noticed how my smoke detector knows exactly how "brown"...Leave a comment:
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Re: DC Inrush current limiting circuit ideas
The schematic was created in [URL="http://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html?gclid=Cj0KCQjwi8fdBRCVARIsAEkDvnLMhRncZkQT-dcaBjBvbRCCKl0mB9sGQ2sby3B1xFqeGTiha--70MIaAuO4EALw_wcB"]LTspice[/URL] which is a free simulator tool - so you can try ccts out without popping anything! Yes, approx r*c gives the time constant. The Mosfet gate takes no current so it's pretty academic what R you use. I was aiming more at getting a couple of mA into the zener. BTW, that's an essential part to...Leave a comment:
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Re: DC Inrush current limiting circuit ideas
D2 discharges C1 through the load when supply removed to reset delay for next time. Component values give roughly 0.5 seconds - if that's too short or long adjust C1 x R1. But watch out how long the Mosfet is in the linear region. May dissipate power if too long....Leave a comment:
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Re: DC Inrush current limiting circuit ideas
I far prefer the Mosfet solution
If you've got any N-channel parts kicking around in a TO-220 pack they'd probably do. So long as the Ron resistance is below an Ohm or so. The Zener wants to be between 7.5 to 15V and the R C divider set up to give the time delay you want. I reckon you could probably pull all those parts out of a duff PC PSU.Leave a comment:
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High side Mosfet swich design
I need to switch a 30Amp resistive DC load from a 5V microcontoller pin. This isn't PWM just occasional on/off.
I'm familiar with the design considerations for high speed switching - rapidly getting charge in and out of the gate to minimise time spent in the linear region but in this application I'm pretty sure I can safely simplify the design a great deal because it's only used as a discrete on/off control.
What I've come up with does seem uncomfortably slow so I thought I'd ask around in case I'm missing something!
Q1 would actually... -
Re: Standard UK sockets
Multi-socket adapters are pretty much essential in HiFi, TV cabinets and on electronics workbenches but you have to be mindful of the kind of appliances you plug in. stj is right to warn about the danger of drawing close to the 13A limit. The construction standards of typical multi-socket adapters tend to be nowhere near as good as those found in the kind of outlets built into houses.
I like to fit the mains plug of a multi-socket adaptor with a 5A fuse just to make sure it doesn't accidentally get overloaded. Four lots of up to 300Watts can...Leave a comment:
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Re: Altering a cat toy?
Well, it [I]does [/I]work. I left out R1 and changed C2 to 1nF to get around 1 to 10 seconds on-time depending on how hard it's poked. I'm not sure how the physical side of things would work out inside a toy though. That's with a FQP7N10 mosfet I had laying around on the bench.
Re: Altering a cat toy?
Well, it [I]does [/I]work. I left out R1 and changed C2 to 1nF to get around 1 to 10 seconds on-time depending on how hard it's poked. I'm not sure how the physical side of things...Leave a comment:
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Re: September equipment offer (u.k.)
One satisfied customer here. Bought it last year and have had no issues....Leave a comment:
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Re: Altering a cat toy?
How's about using a piezo to trigger a mosfet for a short duration - the cat pawing the mouse should make it react for a while then shut off.
The piezo generates a small voltage when hit, rectified by D1 and held on C2. R1 discharges this over 4 or 5 seconds and while above the gate threshold of M1 (around 2V) the mosfet holds the motor on. D2 clamps the gate voltage to a safe level.
Even a fairly small piezo should work OK for this and the best thing to do is add mass to it by sticking a steel nut or lead fishing...Leave a comment:
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Re: LG Washer/Dryer Power Fail
I was just thinking slightly differently about the overheating... the T0220 heatsink looks to be about 12C/W and it's getting to 120C over ambient therefore the TOPswitch is dissipating something in the order of 10 Watts. The converter efficiency [I]should [/I]be something like 80% which implies an active load of 50 Watts. But I know the AC power going in is only half this when the switcher overheats - so it has to be that the TOPswitch is only running at 40% efficiency for whatever reason.
I know this is just more "spinning the...Leave a comment:
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Re: LG Washer/Dryer Power Fail
Oh, perhaps I have that to look forward too :-( Pretty major disassembly you took on there!...Leave a comment:
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Re: LG Washer/Dryer Power Fail
Thanks for the vector to the AN. I noticed that the output diode for the fan supply also runs very hot. I can't find the part's spec. it's case code is 3L2 125 It measures 0.46V forward drop on the diode test range. I guess it's a fast recovery Silicon diode not a Schottky.
I did briefly try a 1N5822 (40V PIV Schottky) in place but the actual PIV must have been too high because it went into break-down. Good thing the current limit(s) kept things sensible. I've swapped it for a 2A 100V PIV Schottky in the same SMD package size...Leave a comment:
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Re: LG Washer/Dryer Power Fail
Oh! I really done goofed.
I can't begin to explain what led me to read that wrongly. So now it's even more baffling...
Going back to my plug-in power meter test, and seeing 8 Watts from the AC input then @ 80% eff., the baseline load supplied by the TOPswitch when the machine is idling is just 6.4 Watts. I can then easily and repeatably get a 80C+ rise on the part by adding 13.5 Watts of load by running the dryer fan for 5 minutes. This takes the IC from around 60C when idle up to the ~140C trip-point. Surely even the TOP244YN...Leave a comment:
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Re: LG Washer/Dryer Power Fail
I just can't be doing with carting a machine that's 99% functional to the scrapyard for the sake of the 1% of its faulty components that stop it from working (says the man with two 25 and 50 year old cars in his garage awaiting repair). The S.Korean joke is the big sticker on the front boasting a "10 Year Guarantee" on the DC Motor. If there's no way the rest of the product would last that long it's not a lot of help although if it did come to scrap I would definitely recycle that motor for something - a wind turbine or E-bike perhaps....Leave a comment:
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Re: LG Washer/Dryer Power Fail
Nothing printed on it. The three poles all measure 4 Ohms but there's no other spec I can find....Leave a comment:
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Re: LG Washer/Dryer Power Fail
A few observations about these LG washer dryers while I'm waiting for parts to show up :-)
The Direct Drive drum motor is pretty neat and seems quite well implemented. The motor inverter is powered by the 330V DC obtained from the 330uF/450V capacitor. The spec gives it as drawing 440Watts at max load. Speed is smoothly variable and very quiet compared with other brushed motors I've experienced in this kind of application. It uses hall effect sensors to determine the relative positions of the rotor and stator so the drive is very efficient....Leave a comment:
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