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  1. Hi, thanks. I have another doubt: That 3M mask is branded as "NIOSH approved N95", but NIOSH is an american standard and I don't know its European (or spanish) equivalent. This other 3M mask seems similar but it's categorized with the EN149:2001. I don't how well relate to the other. From a description here: Which one should I choose??
  2. Thanks. My doubt is that I have always been informed that is not good to blow on the solder joints because a cold welding may appear. Could a fume extractor form cold weldings?
  3. Hi, I need a soldering mask to filter the smoke that comes from the resin on the solder. I have seen many models from 3M, from 7 euro to 30+. They have interchangeable filters. The problem is I don't know if those models are designed for this purpose as they are clategorized for gas, particles, organic or inorganic, etc Any advices?
  4. Thanks for your reply Sarma: Things I did: -Search for service manual: so far no luck. It exists but all of the pages storing it are pay services. -Searched for the maker: Hard to know... The references described above yield references in google but it leads me to pages where the part is listed or even available for purchase but no further info, no datasheet, no specs, nothing. -Searched for a replacement/reseller: There are some in internet but prices are high (60 or 100 euro I have seen), sum the cost of shipping of a piece that weights 2 or more kilos and they will rip my pocket. The cost alone is to much for this, I would consider first buying another equipment... Things I haven't done: -Ripping apart the transformer and rewire it... to hard to me I think. Those voltages are wild guesses or based on my commentary about the caps? Regards. PS: From the back of the cassette: "AC230v 50Hz 70W".
  5. Thanks for your reply. The equipment is a Sony CMT-CP2WA. I have an open thread here asking for a service manual: http://www.electronics-lab.com/forum/index.php?topic=10796.0 The transformer itself has the configuration attached above. Externally it has a gray chasis, is non-toroidal, weighs a bit, and has a metallic plate perpendicular to the pins side with drilled holes to screw it inside the equipment. Going from the outside to inside I see: -Gray metallic chassis -A copper-coloured sheet that is surrounding the core (it is not a winding, I don't know what it is, maybe to capture EMI?) -The iron core -One of the winding fits inside the iron core -Two plastic pieces where the winding is rolled -And... something else but it's under the plastic piece and can't see it. Nothing really remarkable, and I cannot take photos. There is a sticker on the gray chassis: And a molded reference on the plastic pieces that carries the winding: To me it seems like those plastic pieces are standard made and they build different transformers joining different pieces. I don't find any logo. I did search google for the part number but no luck.
  6. Also have you upgraded your adapter drivers or change your monitor configuration, like refresh rate, color depth or resolution?
  7. My audio equipment burnt its transformer. I know it's only the transformer cause I unplugged the supply board (composed of the transformer and some diodes) and started to smell weird, some smoke coming from it, etc :P To pinpoint the problem to the transformer, I desoldered it and plugged directly the primary to mains with and ammeter in series, and in the secondary there was no load. There were about 1,5A when I unplugged mains just to avoid it being burnt. Unfortunately, with these tests it broke one of the primary windings. 1)How can a transformer become shortcircuited internally when it has been working just fine for years? 2)How can I know the ratio if some of the windings are broken? Also, after rectification, the voltage of both secondaries goes into two pairs of capacitors to generate a simmetric supply. There are two pairs: -2x4700uF/35v -2x1000uF/25v 3)It is safe to choose a transformer with two secondaries, so each one gives a DC of 70v and 50v (actually lesss, just to leave a margin)?. I attach a scheme of the transformer and the value of the windings in ohms. The pin marked as "BROKEN!!" is where one of the mains is plugged. The windings used on the board are the ones formed between that pin and the two pins at the right. The measured ohms are relative to the "N/C" pin, which is a no connect pin on the board and thus not used (I've included it here just for information purposes).
  8. Hi, I'm trying to find this service manual. The CMT-CP2WA is an integrated double tape deck/cd/tuner. I have found it in some pages but all of them are pay-per-download (and not cheap). They have it at getmanual.com, which is a pay site, and allow to download a pdf page. There is also another model branded CMT-CP2W (notice the missing A) which seems like the same, maybe just for another market. There are also the CMT-CP11 and CMT-CP11K. Both of them are pretty much the same as the CMT-CP2WA, only difference is that those have a single deck instead of two. It is safe to assume that both (single and double deck) may share most of the design and parts? (check photos). If you can't give me a copy, but have otherwise access to the manual, please, take a look at what mains transformer does it use. Mine has its primary burn for an unknown reason after several years of use and because of this I can't even calculate a transformation ratio since I can't test with an ohmeter. I need to know the brand and model of the transformer and also what are the voltages at the secondary (so in case I can't purchase one that is the same I might be able to change it for another with equal characteristics. The rest of the equipment is all right). Thanks in advance. CMT-CP2WA/CMT-CP2W (double deck): <-This is mine CMT-CP11/CMT-CP11K (single deck):
  9. Thanks. Yes, it's a sine wave 1Vpp, forgot to mention... I don't know how to tell if it has harmonics (I've a very vague idea of this). It comes from a function generator and in the oscilloscope seemed clean. The point is that even if the 100Hz signal gets to the output of the high band filter that doesn't explain why this only happens with the low frequency band at 0.1, does it? I might be missing something. I've to do some measurements today because I don't have an oscilloscope at home... Will se how much of the 100Hz signal gets across the high band pass filter. Regards.
  10. Hi, I've built a 3-band equalizer based on 741 op-amps. It's composed of three stages (you can see them from left to right in scheme adjunted): 1- Pass-band filters 2- Amplification/attenuation (x10/x.1 adjusting the potentiometers) 3- Adder (sums the three bands) The top op-amps are the low band (20-200Hz) The middle op-amps are the middle band (200-2kHz) The bottom op-amps are the high band (2k-20kHz) There is a strange phenomenon. Everything that follows is for an 100Hz input signal which should be only amplificated by the top part of the circuitry. However... -If I have a high gain of the low band and move the potentiometer of the high band nothing happens at the output. The high band doesn't affect it (this is normal, right?). -If I have an attenuation of 0.1 at the low band and move the potentiometer of the high band the output gets very affected... Why? I can expect some influence from the middle band over the low and high bands because they are adjacents and there is the 20dB/decade slope and all that. But how can two sepparated bands affect each other?? Even more: how can the low band get affected ONLY when its gain is 0.1?? BTW This is for a class assignment and the teacher said it's normal, but I can't figure it out. I supposed there was some limitation on the input voltage of the adder so I only noticed the effects of the high band gain when the low band was at minimum, or the signal at the output of the low band amplifier was somewhat going backwards thru the amplifier of the high band?? But that doesn't quite explain why it only happens when the low band is at 0.1... Thanks for your reading.
  11. Thanks. Could you point me to a circuit that you know is working? Most of the high voltage inverters I found use some transistors and a transformer (I doubt there was a transformer in there). EDIT: Now I have the name I'm doing a bit of research. Technicaly an EL panel is a capacitor which if has to be feed with a alternate sginal would make it a unpolarized capacitor. But wikipedia doesn't talk about inverting the DC and my panel is polarized.... The only thing that's clear is that it requires high voltage. EDIT 2: Nevermind. It needs an inverter as you pointed out. I've found a manufacturer page with information: http://www.seiko-precision.com.hk/html/el-catalogue.html However I want to know how can I drive the panel without a transformer.... (cause there wan't none)
  12. Hi, I've savaged an old mobile phone (an LG, about 5-7 years old, I'm not sure really). There's a plastic sheet of yellow-greenish color behind the LCD which is for illuminating the LED
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