CG2
Member
Last Activity: 03-14-2024, 07:01 AM
Joined: 11-13-2022
Location: Brighton
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Is it that hard to test diacs? It looks OK and isn't shorted. My "test" was to connect it up to one of those cheap component testers which said "defect device" The triac checked out OK on the same bit of kit. Those little diacs cost virtually nothing anyway, so I've ordered some, but might try changing just the potentiometer and see what happens. -
Thanks. The triac checks out OK, but it looks as if the diac went instead. The potentiometer is gone as well, but they seem to be available cheaply on aliexpress [url]https://www.aliexpress.com/item/1005005632064132.html[/url] The wiring on this is scarily thin. I'm guessing that someone stuck in a couple of 60W bulbs and that killed it.https://Thanks. The triac checks out... scarily thin.Leave a comment:
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LED uplighter dimmer burnt resistor
I've got a 240v LED uplighter which isn't working. Pulling it apart shows a clearly burnt resistor on the circuit board, and I'm hoping some of you will have suggestions on what to replace it with. First, here are some photos. Power comes in, through the fuse and choke, then through the big blue variable resistor labelled B500K (ignore the similar blue component at the bottom - it's a simple switch for an attached reading lamp). It then passes through the burnt resistor (or at least did once), through diac DB1 and the unburned 30 ohm resistor to the gate of the triac.Now I assume there's a simple... -
A small correction to my post #7 above. The inductor is 1mh (or as the datasheet prefers to say 1000 uh). If anyone wasted their time googling for a 1H that would fit the allotted space, I apologise.Leave a comment:
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Re: Hotel Chocolat Velvetiser dead
Thanks for your help. Post has been a bit slow due to the holiday weekend, but it finally arrived and everything is working again. It's interesting to see another approach to EMI noise suppression. I did wonder why there was no filtering on the input as you usually find on these small SM power supplies.
For anyone else stumbling across this page in the future, the primary side of the power circuit is almost exactly as that on page 18 of the datasheet that lotas posted above, although a transformer has been chosen that outputs something...Leave a comment:
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Re: Hotel Chocolat Velvetiser dead
Current draw at 6.5v jumped between 5mA and 14mA as the LED flashed. Pressing the button added at most another one or two milliamps, so I don't think there are any shorts on the secondary side. The temperature sensor has a resistance of 167k at room temp, so that looks OK, and the motor is 16.5 ohms, which at 12 volts equates to about 0.75 amps, so nothing unexpected.
Now a bit of documentation for anyone else who comes to this thread in future. The relay is a Y32F-SS-112DM which is 12v switched and rated at 5 amps so operating well...Leave a comment:
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Re: Hotel Chocolat Velvetiser dead
I'm still not sure what the output voltage of the PSU is. The article I linked to in my first post suggested that the motor worked on approx. 10.5 volts, and I can't see any other power sources on the board other than this one chip. My board is slightly different, but I wouldn't be surprised if it was all running on 10.5v. My cap tester is a Peak Atlas, and it's always been reliable.
[url]https://helpfulcolin.com/repaired-dualit-milk-frother-model-dmf2/[/url]Re: Hotel Chocolat Velvetiser dead<b... not sure whatLeave a comment:
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Re: Hotel Chocolat Velvetiser dead
Thanks, that looks like the one. I think I'm on the right track, because when I soldered a couple of wires to one of the output capacitors and fed in voltage from my bench PSU, the LED started flashing slowly once I reached about 6.5 volts. I guess the flashing is an error code, probably because the temp sensor is not plugged in. Whatever it means, it shows that the MCU is not dead, and is staying awake when powered.
Now to work out exactly where the fault is. The feedback circuit for the MP020 seems idnetical to that on page 17...Leave a comment:
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Hotel Chocolat Velvetiser dead
This is a fancy milk frother, apparently almost identical to the Dualit DMF2, but sold at a big mark up as bring particularly suitable for making frothy hot chocolat. It's basically a small jug with a kettle type resistive element in the base, and in the centre of that a small motor holding a magnet which locks on to a magnet in the base of a stirrer inside the jug which spins and froths up whatever liquid is inside.
I've got one and it's not working. I've checked all the obvious things. The heater coil has continuity, as do the two thermal fuses and the motor windings. The temperature... -
Janome DC3050 Sewing Machine Pedal Resistance
OK, this is a long shot. I got this sewing machine cheap because it's end of line, ex-display, and had no pedal. The genuine pedal costs £60, while Ebay knock-offs go for around £15. So I went for the knock-off, it doesn't work, and I'm not sure whether it's the pedal or the sewing machine that has the problem.
Now this is an electronic machine, unlike the old fashioned sort where the pedal was a big resistor in series with the power to the motor. Here, the pedal is just (I think) a variable resistor fed with a 5 volt supply, and limited to a current of 5 milliamps. Assuming that... -
Re: Trying to repair an Air fryer EAF383
It's almost always the thermal fan that goes on these. That big black plastic part will come apart somehow (the nut holding on the fan may be reverse threaded). Those two white wires going through the hole to the right of the element are the ones that are connected to the fuse. When you jumped them you bypassed it.
Otherwise check for continuity across the fan windings. There's sometimes another small thermal fuse hidden in there.Last edited by CG2; 04-14-2023, 07:17 AM.Leave a comment:
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Re: Replacing UC3835A PWM controller with UC3853A
For the back story, 5 or 6 years ago I bought a job lot of 3 or 4 ATX PSUs at a salvage auction. Think Amazon returns, but they could have come from half a dozen or so different retailers. I needed one at the time, at least one worked, and a couple were dead out of the box, but otherwise brand new so they went into a cupboard and got shuffled around a bit over the years and eventually were forgotten. I stumbled across one a few months back, tested it a bit, tracked the problem down to the UC3843, bought some from Aliexpress, and...Leave a comment:
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Replacing UC3835A PWM controller with UC3853A
As per the title, I've got an ATX PSU that's only giving 5v standby. I've checked the mosfets and diodes, and they all seem OK, so my next suspects are the output monitor chip (DM311) and the PWM controller (UC3845A). I'm too much of a coward to try to test these live (the PWM controller is buried between the two heat sinks), so now I just start swapping things out. I don't have any of either to hand, but what I do have is some UC3843AN, which are the same family as the latter, but a slight variant.
According to the datasheet, the first digit relates to operating temp. They're... -
Re: Electric blanket resistor
I can't tell how that particular circuit works, but I took a broken controller apart a couple of years ago out of curiosity. power came in via a thermal fuse which was glued to a high value resistor wired in parallel to the main heating wire. In normal use little current passes through that resistor, but if the heater breaks, it soaks up everything, overheats and pops the thermal fuse. Bin it and buy a new one.
50-60 watts per side is common for an electric underblanket. It's surprising how hot that makes a bed when there's a duvet insulating...Leave a comment:
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Re: Liebherr Fridge Freezer KGT 3456 not working
It's not really a latch, nor a safety mechanism, just a stupid bit of over-engineering that's a bit hard to describe. There's one part of the handle that is fixed, and comes straight out like a normal fridge handle. Then there's another part attached to it that is hinged on that part and sits parallel to the fridge front. One side is the bit you pull, then there's the hinge, and finally a little plunger. When you pull on handle, you're operating a lever which pushes the plunger against the main body of the fridge and thus pushes the...Leave a comment:
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Re: Liebherr Fridge Freezer KGT 3456 not working
Even when this fridge was made, Liebherr were sourcing compressors from outside. The freezer circuit uses an Embraco EMU32CLC, and the fridge an Aspera BPK1058Y. A quick Google tells me loads of fridge companies use these. I guess the compressor companies are cutting corners as much as everyone else nowadays, and the drop in quality is working its way down the line. I'd never thought to choose a fridge based on the compressor used, and I wouldn't know a good one from a bad one.
That does make me wonder what is the difference...Leave a comment:
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Re: Liebherr Fridge Freezer KGT 3456 not working
Genius. I was so convinced there was a big fault that I overlooked the little things. Especially as I've not touched that button ever. The fridge arrived set at 5 degrees and there it's stayed. And it had also begun to give some very short cheeps from the speaker, suggesting that the processor was registering some very brief button presses. I turned it off and pressed the up button 20-30 times, and that seems to have cleared it. I hope that works since it looks an absolute pig to get to that part of the circuit board....Leave a comment:
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Liebherr Fridge Freezer KGT 3456 not working
To be a bit more specific, I've got a 20-ish year old Liebherr that has just stopped working. This was quite a sophisticated beast for its time. It's a twin compressor model, and you set the desired temperatures of the fridge and freezer parts from a couple of little control panels above the door. It displays the actual temps on some eight segment displays there, flashing if it's working to get to where you want it. There's a control board with a microprocessor on it that read the temperature from a couple of sensors, switches the compressors on as necessary, and runs the display. There's also... -
Re: Asus V241EP Bios
D'oh. That's embarassing. There's a Winbond 25Q128JVPQ 128M-bit sitting right beside the battery on the other side of the board. Thanks for the help and apologies for being so dumb.Leave a comment:
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Asus V241EP Bios
I've got an Asus V241 All in one PC with a blank screen. Shows nothing at all. I've been through all the obvious but nothing helps, so I'm looking to flash the BIOS.
There are two flashable chips on the motherboard, a 24C16WP eeprom with a whole 2k bytes, and a 4Mbit 25L4006E cmos serial flash chip, so I'm assuming the latter. I've pulled it and read it, but I can't see anything and neither can UEFITool, so it's either corrupt or encrypted.
I can download the BIOS from [URL="https://www.asus.com/displays-desktops/all-in-one-pcs/everyday-use/asus-v241-11th-gen-intel/helpdesk_bios/?model2Name=ASUS-V241-11th-Gen-Intel"]Asus[/URL],...
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