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Eh, my cast iron has gotten me used to burning myself like an rear end in a top hat, so I can probably handle it. Definitely a good point to consider though, maybe a soldering station so I can set it down for a minute when I need to?
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Jul 5, 2022 20:24
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Pham Nuwen posted:Maybe reflow soldering is a way to go? Apparently you don't necessarily even need a reflow oven, you can just use one of those hot air desoldering irons? It seems like it would reduce the precision needed quite a bit, although you'll still need to apply the solder paste.
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Jul 5, 2022 21:13
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My hands get shaky too and it affects my soldering. A few thoughts on that in no particular order: You definitely want at least an iron holder so you can rest your hand. A lot of solder joints can be as simple as apply flux, touch iron, touch solder, off. Less than five seconds in one place. I can usually get my hand chilled out enough to make that happen. Some joints, particularly large through-holes on big fat ground planes, take longer to properly heat up for a good joint. Reflow and surface mount can be a good solution but don’t underestimate the amount of coordination it can take to get small components on their pads and then get the board moved to the oven. I’ve bumped boards or knocked them against something after going to a fair amount of effort in placement and it sucks. e: what Foxfire said above. I use a hot plate. Bottom line though, try a kit and see! It’s a fun hobby.
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Jul 5, 2022 21:15
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I've got pretty shaky hands too and while reflow soldering does require you to be able to place tiny parts with very fine tweezers, I find it isn't actually as hard as it sounds because I can use both hands at the same time and grip as far down the tweezers as I need to since nothing's hot. Usually I hold one hand against the other as I'm doing it so they're both pushing, seems like they twitch less when they're both actively exerting force like that, and twitching in one hand can be counteracted by the other one. Still probably easier to do thru-hole stuff though, since if you get a good clamp you can clamp the board in place and then just push the iron against the joint with a decent amount of force so it doesn't slip off due to twitching.
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Jul 5, 2022 21:18
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InternetOfTwinks posted:Hey y'all, I'm looking to get into electronics to build myself some midi controller/misc input devices, potentially graduating to building my own synthesizer modules and such. Found some plans online and I think I can put some neat stuff together, exciting stuff. There is one issue however, and it's that I have Essential Tremor, ever since I was a kid. This has made my previous attempts at soldering an absolute motherfucker of an experience, even on relatively easy through hole stuff. I'm wondering if there's potentially a model of iron that would reduce the impact my tremors have on the iron, I imagine a short iron would make a huge difference but I wanted to check and make sure they weren't total garbage or something. Would it help if the soldering iron were held in an articulated arm? Could a counterbalanced arm give you better control? https://www.mcmaster.com/articulating-arms/
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Jul 5, 2022 21:23
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Slanderer posted:Would it help if the soldering iron were held in an articulated arm? Could a counterbalanced arm give you better control? This is a decent idea. I think this and/or a way to hold the pieces in place in the air could be the solution I'm looking for.
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Jul 5, 2022 21:48
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InternetOfTwinks posted:This is a decent idea. I think this and/or a way to hold the pieces in place in the air could be the solution I'm looking for. You can get a panavise PCB holder (or another company's PCB holder) that can do that part for you. For irreguarly shaped boards there are kits you can buy on amazon that have a base plate + arms to grip a board (although idk how steadily they hold it for soldering)
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Jul 5, 2022 21:56
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Oh yeah definitely pick up a Panavise, they're excellent. They make a bunch of different models for all sorts of different jobs but even the basic 201 is a huge help and like thirty bucks: https://www.amazon.com/PanaVise-Model-201-Junior-Miniature/dp/B000B61D22/ I like them so much I own two of that model and one of their larger ones and use at least one of them for... pretty much every single project.
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Jul 6, 2022 00:59
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Can someone explain what I'm seeing on my oscilloscope screen? I'm still working on that radio from a few posts before. You can see that post for what I'm seeing on screen. I've just got the hook of one probe going to chassis ground, no probe ground clip attached. I disconnected the primary transformer and I'm still seeing a wave on the chassis ground. Here's where I made the cuts on the schematic. The only thing in the radio I have hooked up right now is the power switch and its fuse. Does this transformer have an internal short?
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Jul 6, 2022 01:37
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Based on the last post, you're seeing a full 200+ volt peak to peak on the scope? Do you still see it if the switch is opened? What do you find if you unplug the radio and do continuity tests between terminals of the transformer and the chassis?
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Jul 6, 2022 01:58
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I don't really understand what you mean by "cuts" unless you just mean you disconnected that portion and you're only measuring the bottom input part. And I don't understand where you're putting the probe. My off-the-cuff impression is that you don't know that the scope is grounded internally, so you're measuring between some point on the circuit, and aaaaall the way back through the scope probe ground line, through the scope, back through the IEC cable, into your wall, into your breaker box, and then back out to where your radio is plugged into the wall. Do you have a voltage on the output of the transformer, while your ground clip is connected to the output logic ground as well? edit: not meaning to sound curt, I think I do right now, but it's unintentional
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Jul 6, 2022 02:52
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touch your finger to the scope probe tip. leave the trigger and timebase unchanged. you'll see 60 Hz
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Jul 6, 2022 03:09
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BattleMaster posted:Based on the last post, you're seeing a full 200+ volt peak to peak on the scope? Do you still see it if the switch is opened? It just gets smaller if I turn it off. Continuity tests are fine. Either output pair has continuity like it should. None of the 4 output wires have continuity with ground. ante posted:I don't really understand what you mean by "cuts" unless you just mean you disconnected that portion and you're only measuring the bottom input part. And I don't understand where you're putting the probe. You got it right. I disconnected either pair of wires coming out of the transformer where they attached, one at the bridge rectifier, the other heater lines at the board. I just got the probe hooked onto chassis ground, the big metal frame that everything is attached to. I thought that too, so I plugged the radio in my isolation transformer to eliminate the ground path through my house wiring and it's still there. It does this whether it's plugged into the house wiring or my isolation transformer. Here's on:  Here's turned off yet still plugged in:  Please help me figure this one out.
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Jul 6, 2022 03:50
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Slanderer posted:touch your finger to the scope probe tip. leave the trigger and timebase unchanged. you'll see 60 Hz Yeah I don't think it's live, energized mains but that you're picking up 60 Hz interference.
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Jul 6, 2022 03:58
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So, a very important thing for anybody setting up a lab bench: scopes don't float. The ground on the probe is connected internally to the AC protection ground on their outlet. This usually means that the scope ground is providing the reference ground for everything else on the bench, since most benchtop supplies do float (as long as nobody installed the customary paperclip or other mystery wire between the ground and negative posts). If you forget this and, say, have a separate ground path for a power supply, you can short something or get noise from a ground loop. For example: just last week I was playing with a new microcontroller and accidentally clipped the scope ground to the 5V pin. This is how I learned that the power brick for my powered USB hub was also grounded internally. The port hit current limit and shut off and I was left trying to figure out why connecting the scope shut off the programmer. As for your high voltage on the chassis, that could definitely be an isolation failure in the transformer. I've seen one in an audio amp before that was intermittent like what you're seeing. It would just occasionally, late at night, burn a few resistors in this amplifier to a crisp and then go away, so it was impossible to diagnose until it just happened to occur while I had a scope connected. It looked like that, just a little less spicy since it was 120V. A multimeter in ohms mode between the live side of the plug and the chassis is a good place to start. If it reads less than maybe 100k ohms, there's a serious, potentially dangerous short from live to chassis. If it disappears when the switch is off or the fuse is removed, it's the transformer. If it doesn't, it could be caused by damaged wire insulation. e: 88V peak-to-peak in 240V land? That's probably just capacitive coupling. Try the multimeter in ohms mode for safety's sake but it'll likely read open. If you want to get rid of that noise and it reads open from live to chassis on the multimeter, just clip your scope ground to the chassis. Stack Machine fucked around with this message at 04:07 on Jul 6, 2022 |
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Jul 6, 2022 04:01
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Sorry, 120V land. I'm in the US. This is a West German made radio and this is the German schematic. You should see the alignment instructions. The transformer wasn't perfect when I first opened up this radio 2 years ago. It was originally held together by 4 rivets in the corners, one of which popped the end off and the outer laminations started to separate on that corner. I drilled out each rivet one at a time and replaced them with screws and nuts. I didn't see any major damage though. It's also a new cord and socket too, an IEC 320 C8 instead of the original interlock cord. kid sinister fucked around with this message at 04:24 on Jul 6, 2022 |
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Jul 6, 2022 04:14
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88Vpp is still only a quarter of what you'd see if you slapped the scope across an outlet, so unless something weird is going on it just means you've got maybe 3pF of capacitance or 30MΩ between your case and hot (since it's a 4:1 divider with the scope probe). As other posters have said, that's not incredibly concerning.
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Jul 6, 2022 06:59
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Stack Machine posted:As for your high voltage on the chassis, that could definitely be an isolation failure in the transformer. Just to clarify, you're talking about the radio's power transformer and not my isolation transformer, right?
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Jul 6, 2022 16:35
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kid sinister posted:Just to clarify, you're talking about the radio's power transformer and not my isolation transformer, right? I meant the power transformer in the radio, but again if it's only 88V peak-to-peak I'm less concerned. That said, now I'm wondering about your scope ground. Does a multimeter in VAC mode from the radio's neutral to chassis read 120V with the scope connected? If so there may still be an isolation fault that's being hidden by the isolation transformer.
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Jul 6, 2022 17:46
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Stack Machine posted:A multimeter in ohms mode between the live side of the plug and the chassis is a good place to start. If it reads less than maybe 100k ohms, there's a serious, potentially dangerous short from live to chassis. If it disappears when the switch is off or the fuse is removed, it's the transformer. If it doesn't, it could be caused by damaged wire insulation. I finally got time to sit down with this thing. Hot to ground is reading OL on my DMM, just like it should. Stack Machine posted:88Vpp is still only a quarter of what you'd see if you slapped the scope across an outlet, so unless something weird is going on it just means you've got maybe 3pF of capacitance or 30MΩ between your case and hot (since it's a 4:1 divider with the scope probe). As other posters have said, that's not incredibly concerning. Where did you get the 4:1 divider from? Stack Machine posted:I meant the power transformer in the radio, but again if it's only 88V peak-to-peak I'm less concerned. That said, now I'm wondering about your scope ground. Does a multimeter in VAC mode from the radio's neutral to chassis read 120V with the scope connected? If so there may still be an isolation fault that's being hidden by the isolation transformer. No, it reads maybe 265 mV AC with the scope probe connected. It drops to about 80 if I disconnect the probe. So what's the verdict on this radio's transformer? Good to work? I did manage to get AM to work on this radio very well. FM is giving me fits. I was getting that same big Vpp measurement when I tried to probe the FM frontend's output.
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Jul 7, 2022 00:48
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So, I don't think I can help with the radio above... but I'm home (usually on mobile) and have a sec and figured I'd share a cautionary tale that happened last month: I acquired an old HP power supply, an HP 6113A to be exact, and it has a couple of problems which I'll bother the thread with a little later. Anyway, I'm super careful around any live wall outlet voltage (US). I haven't been working with electronics that long in earnest and I don't want to die, so I keep one hand behind me and have power strips I can switch off whenever I'm powering something up on the bench. This is one of the first things I've really been working on with wall voltage. I've got this thing open and am looking at stuff, disassembling some of it, checking things out, etc. I power it up and start probing around: yep, 120 going into the transformer. Cool. The thing has like 10 taps on the secondary and sure enough, they seem to be correct. Great, let's turn it off. I start checking diodes and such again. I brush against one of the wires... zap... That's weird. it wasn't too bad really. Must have not discharged the caps. This thing has HUGE caps for smoothing. Welp, I'll have to be more careful when switching it off. Next day, more careful, still doing continuity checks, most of the time I leave the thing unplugged, and plug it into the 'off' power strip, then turn it on if I want to check something. It's most certainly 'off' Brush against a wire... zap... wtf! Measure from live to Ground: nothing. Must be the capacitors again? those things can really hold their charge. Short them together, no spark. More checking ...zap... WTF? Measure from Neutral to ground: 120vac holy poo poo... what's going on? My power strip is OFF. keep measuring, all of these power strips can't be bad can they? make it back to the wall. 120vac between neutral and ground. Bring out the Klein outlet tester I had and never used: RED/ORANGE/BLANK - HOT/NEU REV sonofabitch. We've been in this crappy apartment for 2 years and I'm just finding this out. Check two other outlets nearby. Same thing. Proceed to check every other outlet in the place, these 3 outlets are the only ones with the issue. Can't believe it took me as long as it did to figure out, but I don't even like probing live AC if I don't have to. We raised a huge ruckus with the apartment manager and she sent an electrician the next day. He couldn't believe it and was swearing the entire time he re-wired all of 3 the outlets. be careful out there... it's not just your own safety practices you have to worry about.
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Jul 7, 2022 01:49
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namlosh posted:So, I don't think I can help with the radio above... but I'm home (usually on mobile) and have a sec and figured I'd share a cautionary tale that happened last month: Yikes. I don't intend this as criticism (in fact, I think you diagnosed and handled that very well), but this is why I always unplug mains stuff, not just switch it off, as sometimes off buttons don't work the way I think they work. I also keep the cable on the desk where I can see its whole length, so I can easily checked it's still unplugged and also that it's definitely the right cable. I'm not familiar with US electrical code (I'm in Australia - not that I know much more about Australian electrical standards) but outlets are supposed to cut both active and neutral when off right? That's the rules here (again though as you said that doesn't mean whoever wired the house followed those rules)
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Jul 7, 2022 02:20
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kid sinister posted:Where did you get the 4:1 divider from? Unless I misread your earlier screenshot, your highest reading was 88V peak-to-peak, or 44V peak or 31V RMS, so about a quarter of 120V mains. (10MΩ/10pF is the typical x10 scope probe equivalent resistance/capacitance, so 3pF or 30MΩ). You can get a few pF like that just from having a wire running by the case for a few feet, or from internal capacitance in the transformer.
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Jul 7, 2022 02:51
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Splode posted:Yikes. Man, I hear ya… no offense taken at all. And I thought I was being careful enough, but obviously not. I at least learned a lot from the experience, like most power strips here consider it enough to switch just the live/active evidently. If neutral is hot, you’re screwed
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Jul 7, 2022 03:07
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Splode posted:Yikes. Outlets are not switched in the US, they are always on. If you're referring to the power strip, then I don't know.
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Jul 7, 2022 03:30
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There are occasional switched outlets in the US. As in a switch in a separate junction box switches one or more outlets. Usually used so the light switch can control a few table/floor lamps. I've never seen anything but the hot switched on one of these anywhere I've lived (or in power strips, lamp cords, etc. for that matter). I don't know what code says about this practice though and I'm not by any means an electrician, so take that for what it's worth.
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Jul 7, 2022 03:52
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I happen to be handyman and have read a good portion of the NEC. There are indeed switched outlets in the US. It's kind of old fashioned, but they were intended for the wall switch to control lamps. Some houses built late 70s to 1990-ish had split duplexes in bedrooms. The top of the duplex was switched for a bedside table lamp, the bottom of the duplex was always on for a clock radio. Code here for switches is to interrupt the hot/energized wire only. In fact, there used to be a switch wiring method in the old days that's not code anymore called a "switch leg". Basically, power would be ran to a first box, then the hot wire would be ran down to a second box with a switch in it. That second box's "neutral" wire would get repurposed as a switched hot and ran back to the first box to control the fixture there. You could have a switch box with 2 hots and no neutral. It's not legal anymore because new fancy switches need neutrals for internal electronics like motion sensors, night lights, etc. To make a modern switch leg, you need to run a neutral to that second box, even if it will just be capped off and never used. kid sinister fucked around with this message at 04:46 on Jul 7, 2022 |
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Jul 7, 2022 04:35
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Electricity was a mistake
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Jul 7, 2022 04:37
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kid sinister posted:There are indeed switched outlets in the US. It's kind of old fashioned, but they were intended for the wall switch to control lamps. Some houses built late 70s to 1990-ish had split duplexes in bedrooms. The top of the duplex was switched for a bedside table lamp, the bottom of the duplex was always on for a clock radio. Every room in my apartment has at least two sockets that operate like this. One thing I thought was kinda clever was they installed the sockets with switched outlets upside down, so you can immediately tell something's weird about them. I don't know if that's what you're supposed to do but it's helpful 
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Jul 7, 2022 08:40
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namlosh posted:Man, I hear ya… no offense taken at all. And I thought I was being careful enough, but obviously not. I at least learned a lot from the experience, like most power strips here consider it enough to switch just the live/active evidently. If neutral is hot, you’re screwed I'm going to go home and test to see if all my powerboards actually cut both active and neutral now. All that US code stuff is absolutely terrifying.
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Jul 7, 2022 09:46
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Splode posted:I'm going to go home and test to see if all my powerboards actually cut both active and neutral now. The only switches that cut both phases here are those that use 240V. Even that wouldn't be hot and neutral here, but hot and hot. They're mostly internal to 240V appliances.
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Jul 7, 2022 19:08
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I hate my switched outlets, I wish I just had a real light in the ceiling
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Jul 7, 2022 19:19
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I think we should clarify here the difference between the US having a light switch that turns off a random outlet in a room, and the switched outlets other countries have where there is a switch on the outlet to allow you to turn outlets off to actually turn off devices that have an "off' mode that isn't really off.
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Jul 7, 2022 19:36
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If you're not renting, there are ways to make it happen. If you are renting, look into swag lamps. Shame Boy, what's the verdict on my transformer? Use it or not?
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Jul 7, 2022 19:37
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I don't think the transformer is the issue, you're chasing ghost signals
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Jul 7, 2022 20:07
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OK then. What should I be checking? Make sure my FM oscillator is oscillating? Because this thing seems dead yet is receiving power.
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Jul 7, 2022 20:18
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Can't comment on your particular case, but when I'm troubleshooting my own poo poo where I 100% understand it, I start with my scope on the input (AFTER the transformer in your case) and work my way downstream, checking that every block looks and does exactly what I expect. If something looks off, I stop to investigate, understand better, or fix it, depending
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Jul 7, 2022 21:09
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kid sinister posted:OK then. What should I be checking? Make sure my FM oscillator is oscillating? Because this thing seems dead yet is receiving power. I assume you've checked the supply voltages, including looking out for shorted/leaky capacitors? Old stuff sometimes used R-C filtered supply voltages for noise sensitive components, so a shorted bypass capacitor might not blow any fuses but still cause issues. Leaky AC coupling capacitors can throw off the operating points of circuits making them not work as well, so check whatever voltages are listed in the schematics at least. This 60 Hz chassis issue is almost certainly irrelevant, if the chassis isn't grounded to the mains supply (that is: connected to the protective earth of the power, not to neutral) then it will float at something like half the supply voltage or so. If there's no DC short between the AC live/neutral and chassis then just hook up a ground to it (or use the scope probe). You will need to check and verify the signal path, from antenna to discriminator to audio section, it's impossible to give you specific things to check based on what you've posted so far. Is this a tube radio? If so make sure at least the filaments are glowing, but tubes can be bad even if the filament works. Taking a shot in the dark based on little information, assuming it's a super heterodyne. Discriminators in very old FM radios can be one of multiple designs. Signal path: make the antenna input is amplified and makes it to the first mixer. There might be an AGC system controlling the amplifier gain as well, make sure that's working as well if so. Make sure the 1st local oscillator is running at some sensible frequency (tuned freq. +/-10.7 MHz or so most likely) Check the 1st mixer output (1st IF) is at the correct frequency and a reasonable amplitude. If it has a second IF stage then repeat for that, if so it'll likely be converting to 455 kHz. Discriminator: depends on the type, might be a slope detector, foster-seeley, or perhaps a quadrature detector if it's slightly newer. You'll have to work out what type is used and troubleshoot based on that. The input to the discriminator is likely a square wave or at least a very strong signal, since it will pass through some filters and a limiting amplifier before going to the discriminator. You might also want to go backwards and check that the speaker is working by disconnecting the discriminator and applying some external sound source (or just touching the wires with an insulated screwdriver might be enough to get some hum). If there's no sound at all, not even background hum/hiss, then the audio amplifier or speaker might be bad so start there.
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Jul 7, 2022 21:15
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Splode posted:I'm going to go home and test to see if all my powerboards actually cut both active and neutral now. In the UK they have........  ring mains
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Jul 7, 2022 21:58
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| # ? Jun 11, 2024 03:06 |
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Most impressive yard sale score of my life, particularly because I rarely ever stop at yard sales.   I think it's actually brand new. Genuine Hakko FR-301. It was in it's original box with everything, tip still had a solder plug. Labeled with a piece of tape as "soldering gun $20" alongside some other general electronics stuff (cracked akro drawer organizers, general detritus). I didn't argue about the price.
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Jul 7, 2022 22:07
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