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  1. KrisBlueNZ

    ID diode help

    Alternative spelling of PMSL - "P*ss(ing) myself laughing"
  2. KrisBlueNZ

    Need help with fixing pc subwoofer+speakers please

    It seems unlikely that both power amp ICs would fail. Pin 7 of each output IC is the mute/standby control input. These inputs on the two output ICs are connected together. Check this voltage; if it's more than 2V lower than the supply voltage on pin 9 (the 20V rail), the output ICs are being...
  3. KrisBlueNZ

    stereo capacitors

    OK. You need to plug the red probe into the middle socket on the multimeter for normal measurements. That's the socket marked "VΩmA" or something like it (I can't see all of the marking in the photo). The top socket on the multimeter, marked "10A", is only for measuring high DC currents, using...
  4. KrisBlueNZ

    ID diode help

    Yeah, either throw them out or send them to Guangdong Market so they can get a street urchin to paint "MBR340" on them. Then you can buy them back on eBay and your marking problem will be solved!
  5. KrisBlueNZ

    Art Project Help (Complete beginner)

    What I'm talking about is just a timeline showing when events need to occur. Since you have two lamps, there would be two timelines, one above the other, one for each lamp. Use symbols on each timeline to indicate start and end of Morse code bursts, or even better, show the individual dits and...
  6. KrisBlueNZ

    Treadmill, strange problem on Motor control board

    Opto-isolators aka optocouplers. That's some pretty good general advice there Joe.
  7. KrisBlueNZ

    Add pre-out on Sony stereo receiver

    Yes, that's what the ground lift switch is for. You should have the new power amp physically close to the signal source to minimise the length of the signal leads. Use screened cables, of course.
  8. KrisBlueNZ

    Detaining max load capacitance before pulse transitions are distorted

    According to http://www.edn.com/electronics-blogs/all-aboard-/4424573/Rule-of-Thumb--1--The-bandwidth-of-a-signal-from-its-rise-time the highest "significant" frequency component in a signal of rise time t is 0.35 / t. So in your case that would be 3.5 MHz. So that means the cutoff (-3 dB)...
  9. KrisBlueNZ

    Detaining max load capacitance before pulse transitions are distorted

    OK. Can you determine the highest "significant" frequency component of a signal that rises from 10% to 90% of its total swing in 100 ns and also falls from 90% to 10% of its total swing in 100 ns?
  10. KrisBlueNZ

    Detaining max load capacitance before pulse transitions are distorted

    "significantly" distorted... Again this needs to be defined. Have a look through your notes and see how they define it.
  11. KrisBlueNZ

    Need help with fixing pc subwoofer+speakers please

    Oh, X-210 is the model number! Sorry. Thanks for the photos. OK, so the output ICs have their 20V DC supply voltage. That's a good start! I don't see anything wrong with those joints on those pins, but if you're not sure, you could resolder them. This is actually best done when the ICs are...
  12. KrisBlueNZ

    LED TV - power circuit damaged after lightning strike

    OK, that still points to the MOSFET. When you're getting a new slow-blow fuse, get a pack of them :-)
  13. KrisBlueNZ

    LED TV - power circuit damaged after lightning strike

    Probably not. I guess the 1.2 ohm resistor was between the negative side of the bridge rectifier and the source of the MOSFET, right? In that case the MOSFET is almost certainly toast. What's the part number?
  14. KrisBlueNZ

    Power supply

    OK. There's no way that power supply is rated for 9A output. The input diodes, CR1 and CR2, are listed as 1N5401 types, which are rated for 3A. When you measure the voltages on those transistors, also measure the voltage across CR5. It should be between 5V and 6V. If it's less than 5V, CR5 is...
  15. KrisBlueNZ

    Power supply

    Hi Joshua Are you saying that there are two identical copies of that power supply in your console? With separate power transformers as well? And both circuits are exactly identical? And they are commoned at their outputs so they form +15V and -15V rails relative to a common 0V rail? And the...
  16. KrisBlueNZ

    Add pre-out on Sony stereo receiver

    Hi there and welcome to Electronics Point :-) Personally I would take the signal at the top of the volume control. The amplifier you're feeding it into will have its own volume and tone controls, and if you provide a flat signal at maximum amplitude, you can use the two sets of controls...
  17. KrisBlueNZ

    Need help with fixing pc subwoofer+speakers please

    Service information would be pretty helpful. Do you have a model number we could Google? It's unlikely, but possible, that there's a schematic or even a service manual available somewhere out there. Have a good close look at the underside for dry joints. These happen often on single-sided...
  18. KrisBlueNZ

    Need help figuring out AC wiring scheme in toaster oven

    I think we need to see what's to the left of the three wires that enter at the top left corner. Without knowing that, I would assume that the blue wire is neutral, the orange wire is switched phase for the fan, and the white wire is switched phase for the element.
  19. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    Another thing. Is there a penalty if you drive the MOSFET gate voltage higher than the value needed to saturate the MOSFET? (I know that saturation can't be clearly defined with a MOSFET, just as it can't be with a BJT.) What I'm thinking is that if you charge the gate capacitance up to a higher...
  20. KrisBlueNZ

    12V - 350V 200mA converter for motorcycle CDI

    That's great Steve! Thanks for the explanation. I have a few questions though. I think there's a number missing from your equations - the gate voltage at which the MOSFET saturates. AFAIK, Vgs(th) is the gate voltage at which the MOSFET starts to conduct, but there is also another voltage...
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