Search results

Search Forums New Posts
  1. Sunnysky

    Amp In Protection Mode

    dorke, do you agree for this large a positive 7V offset, it has to be insufficient pulldown or voltage from the negative (B) supply rail? Although this should be common to the right channel, so it must be something similar like R641 has opened.
  2. Sunnysky

    Amp In Protection Mode

    anything connected to that NODE is in yellow. This is the left PA output There is a pink positive buffer side and a green negative buffer side to this typical bipolar amplifier. They crossover and share current near 0 and that crossover DC current is adjusted by VR603. Since you had 0.64V...
  3. Sunnysky

    Choosing the right device & circuit to convert DC to AC?

    74LVC14A Here is your square wave signal with variable R in series with fixed R to give f range required using datasheet for a suitable C value. You will need high side and low side MOSFET switches to transfer DC power into AC power.. 10W at a few volts needs a few amps with a 1Ω load e.g...
  4. Sunnysky

    Amp In Protection Mode

    Vout rises to 45V? VR603 which adjusts crossover and output bias current has enough range to turn off output bias current or increase to 30mA depending if phantom offset if fixed. Recall Q609 11.0 V ==>E 13.1 V ==>C Vce=2.1 which starves output stages of any DC current Vce= needs to be ~2.4...
  5. Sunnysky

    sound patterns

    Rajinder, we dont know if there is other audio interference ( music) so the detection can be simple or complex to identify the tone and then the code. only 2 codes? using 10ms burst a) 3 bursts 200ms gap then repeat after 1 sec 2) 1 burst and repeat every sec Will there be more? What are...
  6. Sunnysky

    4066 switches leaking in sample and hold circuit?

    further debug may require a scope to isolate voltage errors.
  7. Sunnysky

    Amp In Protection Mode

    thanks for the corrections. What I meant to say was ... now that I am not rushing my fingers on the keyboard. 1) Q619 conducts if speaker positive current exceeds 3A ( 660mV ) with gain on the collector current. 2) but Q620 integrates this result in a ~ 300 ms delay resulting in a rise in...
  8. Sunnysky

    Amp In Protection Mode

    The goal if the trimpots is to get 0V on the inputs to the blown IC701 on pins 2,3** if they are close. Pin 1 used to offset bias to effectively disable the IC701 THe 1st one biases current for Q603-Collector The second is critical for ** DC null on IC701 . . Q619is like a peak integrator...
  9. Sunnysky

    sound patterns

    MIC>>OP Amp high Q(~40) BPF (tuned to piezo f)>>active peak detector> OP Amp comparator with hysteresis> logic level out to CPU
  10. Sunnysky

    Mixer resistor values

    mixing not the best? or amplifier distortion? or bad speaker? No idea what you have for speakers, cable or amp or output signal quality.
  11. Sunnysky

    Repair delaminated flex circuit

    yes nothing special, 2 part clear epoxy same for delamination. Epoxy is the material used for plastic IC's although it's black. It is brittle so only use on flat parts. there is also a silicone spray used for coating boards.
  12. Sunnysky

    Repair delaminated flex circuit

    Water and air protection sealants also add capacitance which is bad for digital crosstalk, but , it probably won't hurt if you put a thin coating of same over that.
  13. Sunnysky

    Achieving minimum output voltage with buck converter

    yes that would agree on the formula. then it becomes a unity gain Op Amp referenced to 0.8V
  14. Sunnysky

    Amp In Protection Mode

    R601/602 adjust bias currents so compare left right channel for differences from input to output with schematic voltages. Also check ripple on supply 48V, with no load, it should be very small. Do we know what triggered the failure? User? power up, random?
  15. Sunnysky

    Not the right site but you guys seem to know alot

    local repair shops should be able to extract data from SIM card and maybe delete files
  16. Sunnysky

    Onboard charger repair. Value of ZD?

    Zeners regulate by always drawing more current than worst case load, so that at no load, it can survive and full load still draws enough current to limit voltage swing.
  17. Sunnysky

    4066 switches leaking in sample and hold circuit?

    I assume your 9V is constant, but if not you may need to add a large cap to it. You can try larger R values on the original 5k to see if the charge time is insufficient. They make better analog switches with lower R values, or you can use smaller C values if feasible as well. depending on...
  18. Sunnysky

    Voltage Converter or Not?

    looks like you need 3 LiPo's
  19. Sunnysky

    Solar charger circuit help

    are there caps or batteries still attached to,garden PV's? or N.G.? The PV's charge the battery during the day, with a little current, so the LED can discharge it at night when the PV drops near 0. So there is not much current, so equivalent resistance of PV in full sun is R=V/I. The battery...
  20. Sunnysky

    Onboard charger repair. Value of ZD?

    assuming Ohm's Law (14.2V -12V)/22Ω=100mA thus 1.2W when fan is unplugged or fails then zener fails.... hmmm sounds familiar Yes get bigger Zener So Zener is equivalent load => 12/14.2V = Rz/(Rz+22) ...Rz=120Ω Meanwhile Fan 1.2W=V^2/Rf so Rf=173Ω, so when fan is connected the Zener...
Top