Search results

Search Forums New Posts
  1. KrisBlueNZ

    do you know these resistors?

    Thanks Bob. Just two more things. First, I can't find the original data sheet for that relay. I need to know the coil resistance. Can you measure it? With R7 removed, it should measure correctly in-circuit, but just in case Q1 is damaged, you might want to remove the solder from either one of...
  2. KrisBlueNZ

    PC power supply

    I think it's worth checking those resistors. That's why I suggested it.
  3. KrisBlueNZ

    PIC not working

    You didn't post a schematic of your circuit, so I can't check it for wiring errors. There is a problem with line 16. The instruction rlf PORTD,Fdoes a 9-bit rotate through the carry flag. I assume you want to do an 8-bit rotation so that after each delay, the 1-bit moves from bit 0...
  4. KrisBlueNZ

    do you know these resistors?

    That schematic is wrong; you've used the wrong pinouts for the transistors. The L suffix devices have the Japanese pinout. Looking at the flat side, with the leads pointing downwards, the leads are, from left to right, emitter, collector, base. I've copied the component values and references...
  5. KrisBlueNZ

    12V Battery Charger Schematic

    I assume that power source comes from the AC mains? In that case it will have capacitors for smoothing, and if you disconnect the load then remove the input power from it, its output voltage will not drop to zero instantly. The time it takes to drop to the point where the pass MOSFET turns ON...
  6. KrisBlueNZ

    PC power supply

    I'm interested to know whether these caps are in series or parallel. 820 µF is already a pretty high value, which suggests they're in series, but their orientations are opposite, which suggests they're in parallel. Can you post the markings of the ICs, and any large semiconductors. Have you...
  7. KrisBlueNZ

    do you know these resistors?

    OK, I've re-traced the schematic and you were right. It's an unusual design but I think I understand how it works. The way you arranged your schematic made it hard to follow. But there are a number of discrepancies between the circuit references on your schematic and the references you've...
  8. KrisBlueNZ

    Capacitor replacement advice

    Did you read the readme.txt file that was included with the PDF of the power supply linked in post #14? It says: ----- Power supply Samsung BN44-00208A TV model LE32A559(P4F) Symptom: TV will not turn on, just sometimes, when connected to AC power LED blinks short, after disconnecting the AC...
  9. KrisBlueNZ

    RGB controller

    Yes, 320k bits per second is 40k bytes per second, fairly high for a sustained transfer rate. But a 25 µs interrupt interval shouldn't be a problem. Assuming the MCU has an SPI peripheral that does the bit-banging. I suspect that calculating the data will be the bulk of the processing, and that...
  10. KrisBlueNZ

    strong thermal glue for laptop DC power jack?

    I guess that depends on what you buy. My guess is you'd need something rated at 50W, maybe more. I wouldn't buy one unless you think you'll have other uses for it. I don't have much doubt that you'll be able to melt that solder if you can get enough heat onto it. It's up to you how you achieve...
  11. KrisBlueNZ

    strong thermal glue for laptop DC power jack?

    Bummer. That code doesn't mean anything to me, and would be hard to search for unless you know the name of the manufacturer; even then, there's a good chance you wouldn't discover anything useful. Re sizing the new one, you could bring the whole laptop, including the daughter board, into any...
  12. KrisBlueNZ

    strong thermal glue for laptop DC power jack?

    Right. I think that will be unavoidable. If you have a powerful heat source such as a big soldering iron, you may be able to heat up the power socket area to melting point quickly enough that the heat doesn't spread too far, then pause while it all cools down. Also you may be able to identify...
  13. KrisBlueNZ

    PC power supply

    Are you sure those big electrolytics are 20 µF? I think they're probably 200 µF. And they definitely should be in series. That bulging electrolytic is on the output side, so it's probably not the cause of the problem, but it definitely needs to be replaced. Personally, I would replace all of...
  14. KrisBlueNZ

    strong thermal glue for laptop DC power jack?

    Oh, sorry! Right, it can be hard to melt solder on these boards because there are large amounts of copper around the socket connection points on both sides of the board, to strengthen the socket mounting. It may help to cut the metal leads of the socket off flush with the board, using side...
  15. KrisBlueNZ

    RGB controller

    gorgon, are you saying that the interrupt handler should be called for every byte and should return in between bytes? Because if the SPI is driven by an internal peripheral, it can operate at a pretty high clock rate, and the time between bytes could be on the order of a few microseconds. The...
  16. KrisBlueNZ

    12V Battery Charger Schematic

    That's looking a lot better. 1. Personally I like to show the body diode in all MOSFETs. In this design, Q1's body diode is essential to ensure that battery backup takes over as soon as the second regulator's voltage starts to fall, before the input voltage has fallen low enough to turn Q1 ON...
  17. KrisBlueNZ

    strong thermal glue for laptop DC power jack?

    These should be outlawed. In fact, they are, but no one takes responsibility for checking for them. Often the mains power leads use less than half the wire thickness they should, and the insulation can break when bent. That's a huge fire hazard. There's an interesting article from the UK...
  18. KrisBlueNZ

    PC power supply

    In the mains input circuits of switching power supplies, the input electrolytics are normally in series. Are you sure they're in parallel? What are their voltage ratings? It would be worthwhile removing those big resistors and measuring their resistance. If they're connected in series, you only...
  19. KrisBlueNZ

    strong thermal glue for laptop DC power jack?

    I agree with Jagtech too. Don't try to reconstruct the socket. My first option would be to try to find a replacement socket that fits (or can be made to fit) onto the daughter board, and that fits the plug on the adapter. There's quite a variety of dimensions for the standard style DC...
  20. KrisBlueNZ

    Op-amps and transistors for audio

    Would you like me to look for a better device on the Farnell site? I doubt they'll have anything better in through-hole; can you deal with an 8-pin SMT device? It's fine to post links to component suppliers, eBay auctions, etc, as long as it's not for your own personal gain.
Top