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  1. dave9

    Power supply help?

    Focus on what part of the mainboard started getting hot. Granted if that's a linear regulator on it, it may get a bit warm to hot but shouldn't pull the PSU output down that low. The PSU may need new capacitors AND there may be a mainboard fault, both.
  2. dave9

    Has anyone repaired a power supply in a Panasonic FS200 VCR?

    You'll need new belts, new rubber rollers, new PSU capacitors, new vacuum tube display, to lube all moving parts, demagnetize the heads, and possibly more to make it worth the bother. What do you mean "trying to figure out how to remove it"? It's a circuit board held down with screws most...
  3. dave9

    Adding Bluetooth to Older Car Radio

    If you can't get a manual or schematic then you should consider whether it's mechanically switched input or logic switching a mux (multiplexor) chip. If mechnically switched you might just need to connect the analog from the BT to the switch and sever the cassette feed, and put the ground from...
  4. dave9

    Induction spark coil capacitor

    Rapid, Farnell, Mouser, RS, etc. 470nF would be close enough to 0.5uF. Film capacitor, 350V or higher.
  5. dave9

    Repairing a water level detector

    My 9V powered water level detector's sensor is just a pair of wires, terminating in a plastic frame that seals them in so they don't corrode, with external stainless steel contacts. If you lack stainless contacts you could try stainless bolts and if you have trouble soldering to them, put the...
  6. dave9

    Why does a LED tube light need a ballast?

    They need a ballast because they are designed to be drop-in replacements in existing fluorescent fixtures with a ballast that produces a few hundred if not KV range to drive fluorescent tubes, so they have a buck voltage regulator circuit that drops the high fluorescent tube needed voltage down...
  7. dave9

    Need DC motor information

    So you are supplying a piece of wood and we are building you a surfboard. OK! This is a topic far too broad for a forum post. You need to nail down a budget, size, weight, required speed, and consider what parts are available to you in India. Surely there is a forum in India for people...
  8. dave9

    HT echoing too much

    Yes the shape matters, and/or if what you formerly had, had curtains over it. You could get some thick curtains and draw them across the window when using the HT, and/or try orienting the speakers differently.
  9. dave9

    Change in resistance of electret microphone with sound

    I'm curious why this is useful knowledge? I mean that if you wanted to measure it, you'd be passing a voltage through it but the sound itself is producing a voltage so you can skip a step and measure the voltage instead of resistance if you need a sound level reading, or boost it with an opamp...
  10. dave9

    what is master group control module

    If this is really how vaguely the question was presented to you, then the teacher will want verbiage specific to your prior studies, some "buzz words" and lingo that makes it look like you memorized something. :p One way you could do this is establish an economy where the rich get richer and...
  11. dave9

    Electrolytic capacitors: Opinion required please

    In an aqueous solution. I just tested a tin full of petrolatum based zinc chloride (acid) flux and it shows infinite resistance, even with the meter probes as near together as I could get without them touching. I also had the same result with a petrolatum based ZnCl₂ tinning flux with 4-8% tin...
  12. dave9

    Electrolytic capacitors: Opinion required please

    First, I assume the dark mark was not there until after you powered it on with the new capacitor? Second, I would take my multimeter probes and stick them in a pool of that solder flux to see if it's conductive. Third, I would not leave wet flux behind either way, but especially with a highly...
  13. dave9

    Fix A Noisy Refrigerator

    Yes find the noise source. Common culprits are the fan bearings worn out, the compressor worn out, or the rubber vibration isolating bushings worn out. Could be something simple like a cardboard backing is loose and vibrating. You could fill your ears with peanut butter.
  14. dave9

    Electrolytic capacitors: Opinion required please

    No, swapping one with the other of the same specs should not cause sparks. What device are you repairing, and a schematic wouldn't hurt if you have one. Where did the sparks come from? It does seem possible that you have created a short somewhere during soldering OR possibly there was a...
  15. dave9

    How is this hobby cannon made?

    The second pic for succession won't do anything, would need to be more like the following: Previously when I wrote "If you want them to shoot simultaneously you will need to make sure both lengths of ignition wire are very near the same length or else one will take more than its share of...
  16. dave9

    How is this hobby cannon made?

    If you want them to shoot simultaneously you will need to make sure both lengths of ignition wire are very near the same length or else one will take more than its share of current. You might also need two parallel connected 9V batteries to supply enough current, or a higher voltage source with...
  17. dave9

    How is this hobby cannon made?

    The green kinderegg is nothing more than a housing to mount the 9V battery connector (cut a hole and use epoxy or hot glue), the terminal block that attaches the wires (again epoxy or hot glue), with a switch in series between the 9V positive lead and one of the terminal outputs. Right after...
  18. dave9

    12v dc to 10v dc converter

    ^ IMO this is a pretty common scenario. Many, many times I've considered a project and figured I could bang it out in an evening, but then once you get through all the finer details of implementing it... let's just say I have a lot of projects half finished, that work electrically but aren't...
  19. dave9

    12v dc to 10v dc converter

    ^ That hardly completes the project as a durable, mobile power solution. Yes you can just throw heatshrink tubing on something if you're going to hide it under the dash and put a panel mount socket on the vehicle, since nobody wants a cord permanently attached coming out from under the dash...
  20. dave9

    How to remove D-Protection on LG Home theater

    D-Prot appears to be a generic error message that does not indicate a single cause. I'd unplug it from the wall outlet then turn on to see if it goes away, otherwise opening the unit and looking for faults, or is that what you did when you wrote "no sign of burning"? Did you also look for...
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