I can't see any date or batch codes on them that clearly indicate which might belong to a faulty batch...
spleenharvester
Badcaps Veteran
Last Activity: 06-05-2025, 06:35 PM
Joined: 03-21-2010
Location: UK
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Just smashed a fully working one open, this time a Tapo P100 (I trust none of them now so a worthy sacrifice) - it has an identical PCB (2084500437) and an identical spec capacitor in that position but it is ChengX brand this time. It isn't vented but these plugs have not had the same amount of use so I am not certain this issue is fixed.
I can't see any date or batch codes on them that clearly indicate which might belong to a faulty batch... -
TP-Link Kasa KP105 - rapidly power cycling when plugged in
One of my KP105 smart plugs failed today. It started very rapidly power cycling (you could hear the relay clicking on and off and the LED was going green/orange repeatedly).
I was going to just bin it but I opened it up out of curiosity. Found a swollen cap in the corner (bottom right of image). AiSHi brand, 470uF 10V 105*C. Not sure what purpose it serves exactly so can't comment on whether it is appropriately specced. Other members of this forum have reported similar findings with off-brand smart plugs but this is the first time I have seen evidence of this happening with a brand... -
Ok the battery is here, I think the "fault" was actually just confusion with how it works - if the UPS is powered on by the power button while mains is plugged in it seems to run for about 30 seconds from battery before the device acknowledges mains is present and starts charging. I am guessing this is actually normal behaviour.Leave a comment:
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Oh interesting, yeah mine was making a bit of an odd noise from somewhere too. Transformers are reading OK though. I ordered a battery anyway so time will tell if it was just a fluke.Leave a comment:
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Ok weirdly I just reassembled it and it seems to be working now. Will come back if anything changes. (I wonder if that R750 I removed was in fact shorted?)Last edited by spleenharvester; 05-19-2025, 06:21 AM.Leave a comment:
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Pics. Ignore the missing resistor, I had a daft moment and removed it thinking it was shorted.
Have just confirmed 230V is present at the cable from the inverter board to the mains board so it looks like the fault is on the mains board...Last edited by spleenharvester; 05-19-2025, 05:44 AM.Leave a comment:
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APC BE650G2-UK surge strip UPS - not powering?
I bought this UPS as nonworking. Annoyingly they did not mention the battery has been removed so basically a waste of money... but it's here now so I'd might as well do something with it.
The device shows no signs of life when connected to mains. If I connect a lab supply to the 12V battery terminals it powers up, and flashes the LED showing it is running on backup power. However when mains power is then applied it doesn't seem to do respond in any way. So presumably if I put an actual battery in there it would just make no attempt to charge it, it would discharge and then the unit... -
Yeah we decided not to bother with this in the end lol. Just going to get a plain old 12V fridge and put some ice packs in it.Leave a comment:
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So I determined the RS6334 op amp was dead. Replaced it, the M18 battery began charging... then a few seconds later the whole board went completely dead. No VCC. I think the TOP IC has blown again. I can't be arsed with it anymore so it's going in the bin. 😁Last edited by spleenharvester; 05-16-2025, 02:08 PM.Leave a comment:
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I've gotten 3.5/5 repaired now. First 3 worked just fine. Fourth one, I knocked a resistor off and accidentally replaced it with a 10ohm instead of a 10kohm and it never worked again, I think I am just going to scrap that one. The fourth one though, M12 slot works fine but M18 flashes green/red on any battery that is perfectly fine on another charger. Anyone run into this before?Leave a comment:
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Cheers CapLeaker!
Did the second one today, here it is after a fresh coating of Ambersil. This one was more of a nuisance as all the pads were shot. Still looks quite messy but probably as best as my shaky hands can do. It initially didn't work because the 10K resistor was open, I'm not sure if it was blown with the initial fault or if I overheated it but it works fine after replacement.
3 more to go...Leave a comment:
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Replaced the TOP on the first unit today, worked straight away. My plan is to put jumper wire on every pad as I don't trust even the intact ones not to crack in the future.
Looks messy as hell though. I used 22AWG solid core wire. Will this hold or does it need more cleaning up? Also attached the relevant section of the work in progress schematic
I am going to reapply conformal coating once it is done too...Last edited by spleenharvester; 05-15-2025, 03:47 PM.Leave a comment:
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It's an RX 480. If you want to be sure you can take the HSF off and look at the core markings. And also the driver it's running. (Plus it's easy to relabel two near-identical looking GPUs... but you can't exactly mod a BIOS from AMD to Nvidia).
I am guessing you bought this from AliExpress or similar? The RX 480 is significantly less powerful than the GTX 1080 Ti so more than likely you have been hit with a relabelling scam.Leave a comment:
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Good power bank shells for 18650 cells?
I did a cell salvage run on some Dyson batteries to build out a new fleet of Milwaukee batteries and the yield was a lot higher than expected, so I now have a lot of extra Sony VTC4s that are in reasonably good health. I'd like to build them into power banks, there's a glut of shells for 18650s on AliExpress but I don't know which are any good (read: won't explode). Can anyone recommend some (especially the ones that just fit a single cell)? Weld or weldless are fine, I have a spot welder
I suppose USB-PD and/or quick charge would be desirable too
CheersLast edited by spleenharvester; 05-11-2025, 02:19 PM. -
Cheers Sam. I did look into retrofitting AC but you need a load of parts from the junkyard and it could well end up being more expensive than a part-exchange for an aircon model.
I think I am just going to get a simple 12V fridge from a decent brand instead, this seems like a bit of a rabbit hole hahaLeave a comment:
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Powering portable AC from 18650 batteries
We have a Fiat 500 with no aircon that is absolutely vile in the summer. Unfortunately we can't afford to part ex it for an aircon model, or splash out on the Ecoflow Wave air conditioner. However, what I do have at my disposal is three 36V 10S4P ebike batteries, each 360wh, 420wh and 500wh. My thinking was I can get [URL="https://www.electriq.co.uk/p/compact/electriq-compact-air-conditioner"]this 780W 9000BTU air conditioner[/URL], parallel the batteries and power it through a 42VDC to 240VAC inverter.
I assume I will need a diode on the output of each battery to stop them... -
I bought mine for building two 10S4P packs - 2 welds * 2 terminals * 40 batteries = 160 welds per pack. It starts to become a faff real quick.
Plus it's a good investment if you want to build e.g. tool batteries, I broke out the welder again to build a bunch of 5S2P Milwaukee packs....Leave a comment:
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It's Weld+ and Weld- at the top right
Yes a lot of people on Reddit get upset if you do that lol. I don't know how much it really matters in practice, but spot welding is a lot quicker for large packs either way....Leave a comment:
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Reverse engineering of DoCreate DHJ567 handheld spot welder
Hello everyone
I attach a schematic and teardown photos for the DoCreate DHJ567 handheld spot welder. I bought this welder for temporary use while my supercapacitor welder was waiting for replacement parts. It cost only £24, though there is a screenless version available for £17.
[B]Performance[/B]: The absolute maximum it can handle appears to be 0.15mm of pure nickel. Reliability was not great - welds were very inconsistent, ranging from weak attachment to burning through the strip. However, I was able to build a 5S2P pack without losing any cells. It's a bit difficult...Last edited by spleenharvester; 05-08-2025, 04:26 PM. -
Ah yes just found a video with exactly the same fault. Unlike theirs fortunately it [I]seems [/I]like none of my 5 have damage to the surrounding components, nothing short/open, diodes test OK. Internal fuses are all OK, it was just the plug fuse blown. Four out of the five units had one or more pads lifted when removing TOP268EG... fortunately it looks like an easy enough jumper repair.
I'm working on a schematic for both M12-18FC and M12-18C at the moment anyway, will upload them at a later dateAh yes just found a video with exactly the same fault. Unlike theirs fortunately it [I]seems...Leave a comment:
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