- Router sulks, then works. - 4 Updates
- SG3525 over warming - 1 Update
| "Ian Field" <gangprobing.alien@ntlworld.com>: Jun 09 07:35PM +0100 "Micky" <NONONObobbyburns1111@gmail.com> wrote in message news:vlqhlb1d612bipr1jub9csb88hh1ia40bp@4ax.com... > Yeah, now I r emember that we talked about capacitors (on electonics > repair) the last time, and I cracked it open and looked, but I didnt' > seen any that looked swollen. Maybe I just don't know how to look. Electrolytics don't always bulge - sometimes they get hot and expel electrolyte past the rubber bung, when they cool, a vacuum forms and sometimes makes the top slightly concave. If you remove them - the dead ones usually feel lighter than they should. The usual problem is ESR - high internal resistance, this causes losses when filtering the output from an SMPSU. Those losses translate into heat that you can feel - but watch out; electrolytics on the primary side of an SMPSU can have live cans! You could always buy an ESR meter - but the good ones aren't cheap. Some types of combined continuity/voltage testers with 2 LED indication can give a near enough test - one LED "kicks" as the capacitor charges when you press the button, the other LED "kicks" on discharge as you release the button. It takes experience to read how fast or slow the LEDs fade, but I got away with such a tester for years. |
| Michael Black <et472@ncf.ca>: Jun 09 04:04PM -0400 |
| Micky <NONONObobbyburns1111@gmail.com>: Jun 09 05:23PM -0400 On Wed, 8 Jun 2016 22:25:08 -0700 (PDT), "Ron D." >pressed (in the old days where there were actual reset buttons on small >network equipment). >Seen those sort of symptoms all of the time. Power glitching is a good reason for them. If there's no backup batteries within the device, pull the adapter and short the input to the router for at least 39 seconds. I've resurrected a number of things this way. The last device was a wireless mouse. Did the "short trick" overnight and it worked. Usually 30s to 1 minute usually works. You mean the power, right? Not the internet input. >The method has a good reason why it works. I also resurrected a automobile clock that died shortly after a jump start. A bit harder and it was never removed from the dash. There is no internet input to car clocks (well, maybe there is these days) so it's the power. I'll try this sometime. Everything is working now. 39 seconds? |
| "Ian Field" <gangprobing.alien@ntlworld.com>: Jun 09 10:32PM +0100 "Michael Black" <et472@ncf.ca> wrote in message news:alpine.LNX.2.02.1606091603410.17608@darkstar.example.org... > But it's more likely that the electrolytics on the secondary are the > problem. Those run at much higher frequencies than 60 or 50Hz from the > line, which makes them more vulnerable. Not so with the electronic PFC front end. The rectifier output only has a low capacitor film type - the rough DC goes straight to the PFC circuit, that is basically a flyback boost converter, and that's what charges the reservoir electrolytic. Before the proliferation of PFC, I was in mainstream servicing - I had to replace enough rectifier/reservoir electrolytics to complain about how much they cost! For UK mains; the PFC reservoir has to be rated 450V instead of 385V - and handle SMPSU type ripple. So I expect they're a bit more expensive and probably fail more often. |
| "tom" <tmiller11147@verizon.net>: Jun 09 05:03PM -0400 <jurb6006@gmail.com> wrote in message news:a2e2951c-9a12-4a51-8467-4cc0d3c2096f@googlegroups.com... > Hi there > I'm repairing a variable smps based on SG3525 IC. the IC gets too hot and > finally it burns away. what's the problem? That is like way too much not enough information. Is it used to drive a transformer directly or transistors ? If directly, what about the load on the transformer, have you checked the rectifiers on the secondary ? You have to give some fucking information to get help on shit like this. Does the thing, whatever it is, work but then it pops ? Or just fry out and not work ? Get more info out here, and actually the duty cycle of the waveform it is putting out. Get a Dropbox account and use the \public directory for pics like this. When you try to use their picture thing it gets all fucked up. And what is the make and model of this thing ? Unless it is some homebrew custom thing... If you are unable to supply this information you have no business trying to fix the thing. If you have changed that IC fifty times you have no business trying to fix that thing. When I ask for help here I got voltage readings, waveforms and all kinds of tricks I did to find out this and that. Sometimes it works ad sometimes nobody knows. You come in here with a post like that most people think you are a total noob and don't know shit. Now it is up to you to prove otherwise. We can't read your mind or your scope, and you better have one. Of each. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++= Your best post ever. Right on the mark. |
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