Hack Correlation

I was nicely asked if I could take a look at a disabled toaster unit that stopped doing its job. Post-cleanup it looks like this: The quick repair job turned out to be quite entertaining in figuring out post-mortem how the unit failed and the questionable design decisions. It involves no complicated electronics and it might help other people figure out what to look for before buying an appliance. With another layer of failures stacked on top, this unit could have set the house on fire or shocked someone. Fortunately no damages were recorded, but the deep-dive might prove interesting to some people.

I recently got access to a broken Siemens Dressman TJ10500. It's a pro-sumer device that helps you straighten shirts without the tedious ironing. It looks like this: The unit was described as "not heating" or "cooling rapidly". The front panel and every other feature seemed to be functioning just fine. I will describe how to tear down the unit, what can go wrong, what I did to repair mine and how well it works. Teardown To get inside the unit, there are many screws that need to be undone: around 5 at the back of the unit (except the air filter ones), two below (left side with the unit facing you). Then you need to carefully lift up the plastic trim that surrounds the LCD and controls, all around, you will have two more screws just next to the airbag. Most of the screws are Torx T20, some of them are Phillips (PH2 I think). With those undone, you can remove the left [metal sheet] panel, that gets you access to everything inside the unit. The m...

Many years ago (circa 2004) I bought a used Zoom 9002. This worked fine for a while until the output became weaker and weaker. At some point it stopped amplifying completely. I looked online, there was at least one blog post mentioning that some electrolytic caps and the ICL7660 need to be replaced. I did that, nothing improved. I think the display also started failing. "Smart" as I was at the time, I decided that perhaps the board needed some reflowing, so I stuck it in an oven for a few minutes. Packed it good. Fast forward 10 years later: Initial condition This was literally a "basket case" - all the parts were in a basket, with no ideea what goes where.

My old post on the Saeco Talea Giro machine teardown  (including deprecated one ) has had tremendous success and I frequently get questions on how to fix this or that. I am no specialist on this stuff but I've managed to keep my unit running after it was used in an office environment (>50000 coffees). So for me it's mostly guesswork and some logic, but I'll display this so that you can help figure out the problem with your own unit. I'll try to make this accessible to non-technical people, let me know if some idioms are too advanced. I will try to update this guide with usual questions, but this is not a replacement for professional servicing. Before troubleshooting  make sure that the unit is  cleaned and descaled  and has enough water. Use the manual for this, each unit is different. Also, try turn the unit off and on, perhaps leaving it 1h undisturbed. This works around some of the bugs in software (firmware). Learn the sounds of the machine and try t...

This is somewhere between a tutorial and a rant about the X2 self-healing capacitors. The above cap seems fine and measures within spec but the appliance it's set into does not function correctly. In this case it was an RF socket from Aldi operating on 433Mhz. The LED would turn on but the load wouldn't. There was only a small click from the relay. From a set of 4 pieces, 3 have failed in the same way. Sometimes, switching to a lighter (LED bulb) or heavier (washing machine) load would make the problem go away for a few weeks or even months. A [Philips] Senseo Coffee machine failed to turn on - the red light would turn on for less than a second and then switch itself off. A Philips drip coffee maker would turn on initially but turn itself off when starting to heat the water. The common issue in all these cases was the X2 cap, replacing it cured the problem. So if you have the above symptoms just try swapping the capacitor with a new one and see if it fixes the issue....

I bought this unit as broken for what I thought it was a good price, ~10 EUR while the retail price is around 50 EUR. Since I usually buy stuff that's DOA (Dead on Arrival) the fix turns out to be most of the times a cold soldering joint or a blown capacitor. But first, in case you haven't bought one, here's a Quick review I'm surprised that in this day and age manufacturers still produce units without an auxiliary input, such as the one pictured below. It claims to have 10 Watt output (maximum), infrared remote, can play MP3s from a CD or USB stick and has a radio. Let's review all of that, again: The 10 Watt audio output is produced by a SJ2038 chip which can provided a maximum of 2x3.5W into 4 ohms at 5 volts with a THD of 10%. The speakers are 6 ohms which would mean probably around 2x2.8W output at 10% distortion. Probably less than 4W for decent listening. To be fair, for such a low power the speakers sound decent, much better than all of the c...

This is a teardown and 'repair' of a common type of e-smoke cigarette. If you are reading this in the future (say, ten years from now, 2025) smoking is a type of pleasure that's dying in this year - 2015. It's an expensive drug (5-20%of monthly income) that takes a bit worse than soap and makes everything stink. It's still legal while other drugs (THC-based)  are still illegal. It forms a strange addiction to this bad smell and lack of brain oxygenation that augments alcohol consumption. Well, lack of oxygen will strengthen any other drug or high, but can be had even cheaper while trying to stay underwater in a sink. If you are underage and you are reading this then probably the parental filter set on the router has failed. Smoking is bad, m'kay? If you are reading this in the future, some people here are trying to get rid of this so-called nasty habit and enrich their gadget profile. This means that the thing they are trying to replace WITH has a microco...

I was asked to try to repair an Apple MacBook Air A1466 (mid 2012) that has received a cup of tea. When I first heard of the water damage I requested the user to stop using the laptop immediately and take the battery out. However, the laptop was still put in use for a few weeks after which it failed. Had the advice been heeded the extent of the damage would probably not have been so high. The symptoms were: some keys not working, including the power key, screen kept blanking out or flashing colors, laptop shut down by itself. Getting inside is pretty easy, if you have the right tools. You need several strange screwdrivers that can be purchased from iFixit: Most of the damage seems to be located in the upper left corner: Screen (LVDS) cable has a few corroded pins, the power regulator next to the right seems to have been cooking some tea: The screen connector on the mainboard looks heavily corroded: Obviously the water detection sticker has been triggered to a ...

This is a short article on a lighter note. I got a broken keyboard (from boxes with  DOA stuff) with a few keys that were not working. I've opened the keyboard up and marked the keys that were not working, you can see a slight red marker trace in the picture below: The key circuitry is a sandwich of three flexible plastic layers: top and bottom with conductive traces and a middle one for isolation. Only the bottom one was broken. Using a continuity meter the breakage was traced to an area near the connector. As a heads-up, the measured resistance for this type of traces is 5-10 ohms/cm, so for a strip/trace longer than 20 cm the meter might not beep anymore. I had some silver paste sitting around unused, so I covered the broken traces with that.  Some shaking required.... ...after shaking all the silver flakes/powder should be evenly distributed. I don't think they mention this anywhere. I believe a bottle of that stuff is around 15E for 5ml, but shou...

Out of my eBay 'lucky bags' I got a wireless charger for Wii remotes. I forgot about it for more than one year since I did not have a Wii at that time. It came with two battery placeholders that also replace the battery cover of the Wii remote. I've tested the included batteries and they seemed to still hold charge. The unit would not turn on: it's time to void the warranty on this "Kamikaze Gear Wireless Charging Dock (Wii)":

I have a lot of posts in my backlog that have pictures but no text added to them. Since a lot of them are more than one year old I figured I should take the effort to add the text lest I forget what happened. There is a common problem with the DSO5062B oscilloscopes in that they get a white screen once in a while and require a power cycle to recover, temporarily. The scope seems to be functioning in the mean time but nothing is displayed. The same device is being sold under many different name and brandings: Tekway DST1062B, Voltcraft DSO5062B, Zhongce, Protek, PCE (like mine) but it's exactly the same thing save for the splash screen and printed logo. There's an extensive thread about hacking and modding them on the EEVBlog forum. Here's how the white screen syndrome looks like, see below for the fix:

I've bought a cheap broken laptop on eBay for around 20EUR with the description "turns on briefly the fan and the shuts down, no image". The laptop was actually in pretty good condition, came with a working battery and charger and RAM, but without any hard-drive. A quick search on the Internet turned up the fact that these laptops usually die from heat, having inadequate cooling on the integrated video card. I recovered the laptop by using a makeshift heat shield made from a sandwich of aluminium foil and cardboard an using a heatgun (paint stripper) to slowly heat the chip. A blob of leaded solder was used as reflow indicator, knowing that the leadfree solder melts at higher temperatures and the BGA balls take a while to heat up (being under the chip). A cheap multimeter was used as a temperature indicator, with the thermocouple pressed against the chip body. The cardboard started smoking after a while but this did not affect the operation in any way. The ...

Zoom G1 I got this unit essentially for free a few years back after getting rid of my VooDu Valve which was too expensive/overkill. It's a nice little unit great for practicing guitar and has the added bonus of foot switches (the two big knobs at the bottom): This unit has seen better days and it kept switching itself off or resetting once in a while whenever the cables were moved. Also, it didn't want to work on battery power.

I was scoping around to see what caused the 2.5V supply modules to go bust. Just as a reminder, they are pretty generic modules, with a 5V preregulator that steps down the 12V input. The 5V is then dropped through linear regulators to three supply rails of 1.8V, 2.5V and 3.3V. In this application only the 2.5V output is being used.

I got this coffee machine from work because it was a maintenance nightmare. I'll tear it down, do the analysis on how it works and detail on some design problems as well. It's going to be a rather long post with quite a lot of pictures. I've marked all the detected problems with an asterisk " * ", I'm sure some have been forgotten as this teardown was performed 6 months ago. (for troubleshooting see  https://hackcorrelation.blogspot.de/2017/02/automated-coffee-machine.html )

I've gotten two DVR MPEG4 recorders for free because they were labeled as "unfixable". Both of them were diagnosed with "no video" or "video problems".  Ever since I've had them I had suspected the 2.5V supply to be at fault but had no oscilloscope nor variable PSU at hand, so they have been sitting in my drawer for a few months. It was a 10 minute job: - probe the 2.5V output and see it oscillating between 2.4 and 4.2V - probe the PAL/AV output and see the scope could not get a lock even though it looked almost ok - bypass the supply and feed 2.5V from a variable PSU - probe and do a quick run to see everything is stable. I wish I could do a burn test but my trusty variable PSU is a linear one, getting quite hot at this voltage drop.

I've bought a NEC beamer on the cheap (~30E) which ran for about 1 second before becoming dead. In the interest of reference I'm attaching pictures taken with a phone camera so that other people know what they are getting themselves into.