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  1. kellys_eye

    Check individual cells of a car battery.

    Short of dismantling the battery there is NO long-term fix for shorted plates. The 'short' is caused by the buckling of the lead separators that eventually touch each other OR by the collection of conductive deposits that lie on the bottom of the battery and short across the bottom if the...
  2. kellys_eye

    UPS circuit IC

    U7 is definitely an IC and the components around it match the requirements for a voltage regulator typically the LM317 - closer inspection of the resistors and their values might give an indication of the output voltage setting. The parts surrounding the other IC still point (to my eye) it...
  3. kellys_eye

    Check individual cells of a car battery.

    By 'dunking' do you mean into the acid solution or physically onto the cells themselves? If in the acid then the voltage would be whatever the combination of materials the probes were made from plus the acid effect. You CAN touch the plates but you need to touch them at the right place and...
  4. kellys_eye

    UPS circuit IC

    Not really enough info to be certain - sure there's nothing on the devices themselves???? At a guess I'd say the IC was an LM324 and the other one is (potentially) a voltage regulator. Would need to see a MUCH better picture of the board (closer, clearer) and BOTH sides.
  5. kellys_eye

    Heat causing automotive LCD display to dim. Can't find a solution.

    Per my previous advice, a larger copper 'ground' to dissipate the heat would work. There looks to be plenty of space to achieve this. Alternatively you could find a different device that has better heat dissipation properties - either way I reckon you'll have to rework the pcb layout. Haven't...
  6. kellys_eye

    Very high current power supply

    Far be it for me to tell you your business but don't fuse manufacturers provide such detailed information with their products? There are 'standards' that have to be met before they can retail them as their described function. Unless, of course, you are making your own fuses?
  7. kellys_eye

    PWM with 50% duty cycle

    For an inverter (AC out) both halves of the switching cycle produce an output voltage else you wouldn't get the 'AC' part. At 50% duty cycle you are switching at 100% power (50% each side of the cycle). Anything LESS than 50% will be a power reduction. Power is produced at the peak of each...
  8. kellys_eye

    Solder smd

    The 'thin water' flux is possibly IPA (isopropylalcohol).
  9. kellys_eye

    Heat causing automotive LCD display to dim. Can't find a solution.

    Ah ha..... that's a sh1t load of heat you apply to the chip before we see a change in the display and I reckon that it's not the heat on the SRAM that's the cause but the heat moving AWAY from it to some of the components adjacent TO it. This is why I want to see the datasheet for the display...
  10. kellys_eye

    Heat causing automotive LCD display to dim. Can't find a solution.

    If it's not the display then what is it about the data going TO the display that makes the displayed data 'wrong' What parameter of the display changes to cause the 'fading'? Can you provide a datasheet for the display? There may be a timing (heat) issue related to the way the displayed data...
  11. kellys_eye

    Heat causing automotive LCD display to dim. Can't find a solution.

    Update - just checked the datasheet for the SRAM https://pdf1.alldatasheet.com/datasheet-pdf/view/105048/ZMD/U62H64SA35.html and noted its automotive application and wide operating temperature range which certainly clarifies my suspiscion that the LCD itself is the issue here and NOT the SRAM...
  12. kellys_eye

    Can anybody out there help identify these diodes?

    Former techer myself but been self employed for decades now and currently making/selling curries! (quite successfully too).....
  13. kellys_eye

    Heat causing automotive LCD display to dim. Can't find a solution.

    I'm surprised that an SRAM chip can affect a display that way and suspect this isn't the case anyway. It looks 'typical' of a poor CONTRAST issue. Many LCD's either have a PIN to apply an external voltage to 'set' the contrast. Other displays manage this internally on an automatic basis. Got...
  14. kellys_eye

    CADDX NX8E system - looking for detailed info on expansion boards

    Seriously doubt it's going to be a 'data' issue - still most likely to be something in the 'physical' signal path. The transistors that buffer the line for example.....or even the optical isolators (LED failure is a 'thing').
  15. kellys_eye

    Can anybody out there help identify these diodes?

    I'll do 100 'lines' as punishment. Anyone know where I can get that much?????
  16. kellys_eye

    CADDX NX8E system - looking for detailed info on expansion boards

    What about peripheral devices? It would be highly unusual for a high speed data (serial) bus to exit directly from a microchip for tx/rx without some form of buffering (where the transmission signal levels are 'added'). Lightning can cause many issues unless screened cable is unsed (unlikely)...
  17. kellys_eye

    CADDX NX8E system - looking for detailed info on expansion boards

    I doubt there is a propriatory tx/rx protocol involved (all assumption here - no familiarity with these systems at all) so do you know what is used? RS232/485 etc? Can you 'scope the signal and determine the bus voltages and see if there is either an imbalance or loss on one side?
  18. kellys_eye

    Can anybody out there help identify these diodes?

    1N914 (or 1N4148 - either would work).
  19. kellys_eye

    LED circuit contains caps, diodes, resistors, what's going on with this?

    No he wouldn't..... he'd just want something that made sense so he could offer a solution. And @Delta Prime gave you the 'solution' - the LED and driver transistor are quite clearly marked so it's a moot point now.
  20. kellys_eye

    Removing microprocessor

    Y1 is a crystal oscillator module. Only 4-pins. The proper hot air rework tool should be used but, at a pinch, you can 'dance' between all four pins as you apply heat from an ordinary soldering iron and eventually work it loose. A skilled solder-er would have no problem - a beginner would...
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