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  1. (*steve*)

    Need A Lot Of Help

    I don't think it's profitable to go around measuring components at random at this stage. However, you have learned a valuable lesson when using a manual ranging multimeter -- If you are measuring something unknown, you need to start at the highest range and work downwards. If we suspect that...
  2. (*steve*)

    Need A Lot Of Help

    Try the 2M range
  3. (*steve*)

    Need A Lot Of Help

    The wonder of pictures. Those are marked 104 (100kΩ) and 1004 (1MΩ). Your multimeter should read them easily. Are you sure that you are operating the multimeter correctly and that you are probing the right places? Show me a photo of your multimeter when you have it set up in the resistance...
  4. (*steve*)

    Need A Lot Of Help

    NO! You always perform resistance readings with the power off.
  5. (*steve*)

    cap tester repair

    Changing parts at random is not the best way to go, however changing the electroytic capacitors was probably a good thing. At least you have a spare 6BN8 now :-) I assume you have the manual? Given that this was a kit, you also need to consider the possibility that it was mis-wired and was...
  6. (*steve*)

    Wanted: electrical ferrules

    When I needed to do this I just grab one of these Chinese breadboard jumper leads and cut off one end.
  7. (*steve*)

    Need A Lot Of Help

    And presumably this display of "1" is what is shown if the process are not touching anything? 100u and 10u means these devices are capacitors. If you're measuring the right places I would expect you to see some readings first, before the meter settles in an over range resistance measurement.
  8. (*steve*)

    Need A Lot Of Help

    When you say "no reading" do you mean they read 0, or OL? And what are the markings on the resistors (assuming they're large enough to have markings)? I'd probably clean the board using a flux cleaner first (or just distilled water) before drying it by dunking it in isopropyl alcohol. You do...
  9. (*steve*)

    Best soldering technique to prevent component heating?

    That argument is largely irrelevant if you use correct technique. You should be heating the joint and melting the solder on the joint, not the iron. Sure, some flux may burn on the iron, but some is going to activate there anyway.
  10. (*steve*)

    hi fellow hobbyists.. ?about sensors

    No. That's not a good question. What if I give you the answer "47"? Would that help you? A good question might be: "What methods could be used to detect proximity of a wall for my robot? I am interested only in proximity in a single fixed (relative to the platform) direction. I am...
  11. (*steve*)

    Best soldering technique to prevent component heating?

    Work quickly. You should be able to solder the joint in about 1 second. For stuff that is really thermally sensitive (some diodes, old polystyrene capacitors, maybe some transistors) you can use some needle nose pliers to grasp the lead between the solder joint and the body of the component...
  12. (*steve*)

    hi fellow hobbyists.. ?about sensors

    Ancient No, sorry. But if you can ask clear questions, I (and many people here) can put effort into answering them.
  13. (*steve*)

    hi fellow hobbyists.. ?about sensors

    Yeah, sorry, I really don't understand you very well.
  14. (*steve*)

    Flyback transformer testing and replacement

    A few notes on your markup. Firstly, current only flows one way in each of the main windings. Q9 energises the transformer by allowing current to increase in the primary winding. When this current is interrupted, the collapsing magnetic field causes current to flow in the secondary winding...
  15. (*steve*)

    hi fellow hobbyists.. ?about sensors

    It's posts like this that make me wish for a "WTF?" button instead of a "like" button.
  16. (*steve*)

    Replacement of a fixed and adjustable regulators

    In that case it looks like you could just replace these with LDO 3 terminal regulators in a TO-92 package. This would work as the 3V regulator, and this for the 3.3V regulator. Note that both of these have a limited maximum input voltage (6V vs 16V), but considering an LDO regulator is used, I...
  17. (*steve*)

    Replacement of a fixed and adjustable regulators

    I would think that both are fixed 3 terminal regulators. If you know the output voltage and the required current, then you might simply look for another similar regulator. There may be other parameters, like low dropout voltage or low quiescent current that you can also put into the mix. I...
  18. (*steve*)

    Flyback transformer testing and replacement

    This circuit is a flyback converter, and therefore the transformer is a flyback transformer. Some definitions for flyback transformer equate it with a LOPT (a line output transformer). A LOPT is a use of a flyback transformer (once, probably, the most common use), but not the only use, so this...
  19. (*steve*)

    Flyback transformer testing and replacement

    Higher is rarely a problem. The gain of transistors is extremely variable and circuits should not be designed to operate with a certain gain. Having said that, a certain amount of gain will always be required. Choosing a replacement that might have a gain lower than the specified minimum for...
  20. (*steve*)

    Flyback transformer testing and replacement

    Yeah, the BC847 looks fine, but the 2N3904 has a lower gain than the 2SC2812, so I wouldn't choose that one.
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