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  1. Ylli

    Kenwood Receiver Heating Issue

    I think you swapped the reported voltages across R2xx and R1xx. If I swap the numbers back, it makes much more sense. We appear to have 30 mA idle current in the Q2/Q3 branch, and more than 200 mA idle current in the Q4/Q5 branch. 30 mA is good, 200 mA is excessive. Q4 and Q5 have the same...
  2. Ylli

    Kenwood Receiver Heating Issue

    This is actually the same circuit as your last unit. The protection is a bit different, but the audio path and config is the same. I've seen some very good articles describing various audio amps, but I'll be darned if I can find one now. Hopefully someone will have a good link for you. There...
  3. Ylli

    Kenwood Receiver Heating Issue

    Let's start by measuring the voltage across R112, R113, R212, and R213. Put the meter + probe on the transistor emitter end of the resistor and the - on the other end of the resistor. Then let's get the voltages (measured to ground) on collector, base and emitter of Q2, Q3, Q4, Q5. Please...
  4. Ylli

    Need a little advice about Solder Paste's and Hot Air Soldering.

    Forget the paste - it is a pain to work with. Simply tin all the pads, (optional - add a bit of flux from a flux pen), place the device on the pads hold it down and reflow.
  5. Ylli

    Quint Power Supply short

    This looks like you part: https://www.rapidonline.com/diotec-sm2000-rectifier-diode-2000v-1a-melf-do-213ab-64-9132. You probably would want to check all three of them. And the unit itself http://www.farnell.com/datasheets/2326048.pdf Note the block diagram about half way through.
  6. Ylli

    Marantz 2015 Receiver Distortion

    Congratulations! With the low side outputs effectively disabled, I'm a bit surprised you got much of an output at all.
  7. Ylli

    Marantz 2015 Receiver Distortion

    R627 is adjusting quiescent current in the output pair. A class AB amplifier has each output transistor conducting a bit more than 180°, so there needs to be some current flow even with no signal present. If there is no quiescent current (which is your case) you will get crossover distortion...
  8. Ylli

    Marantz 2015 Receiver Distortion

    1.5 volts to ground on the collectors of H617 and H618? We may have found a clue. Do we also have 1.5 volts to ground on J612 and J614? How about on the bases of H002 and H003? Can you measure a voltage at the emitters of H002 or H003? Those *should* be at ground potential.
  9. Ylli

    Marantz 2015 Receiver Distortion

    I'm scratching my head..... Does R621 *look* OK? The voltage drop across R623/R625 is about a volt less than it should be. The voltage drop across H701/H605/R627 is lower than it should be. That all points to the current through this series section is too low. Yet the 0.6 volts at the...
  10. Ylli

    Marantz 2015 Receiver Distortion

    To hopefully improve clarity, this is the DC circuit we are looking at:
  11. Ylli

    Marantz 2015 Receiver Distortion

    I should have specified where to set the pot for this measurement. Please try it with the pot set to maximum resistance. We are looking for about 2.5 volts (three B-E drops) between the bases of H615/H617. You measured 1.4 volts across H701 (which is good). H603 appears to be drawing 6 mA...
  12. Ylli

    Marantz 2015 Receiver Distortion

    Don't mean to disrupt Whonoes ideas, keep following them. I would next measure the voltages at the base of H615 and H617. With power off, measure the combined in-circuit resistance of R627||H605. Try it with the meter leads one way, then switch them and measure again. Do this with R627...
  13. Ylli

    What this?

    Looks a bit like a garage door safety interlock.
  14. Ylli

    Marantz 2015 Receiver Distortion

    If it turns out H701/H702 are defective, it looks like a viable substitute is the NTE605. http://audiokarma.org/forums/index.php?threads/goofed-up-need-a-little-help-please.109025/#post-1130103 http://www.nteinc.com/specs/600to699/pdf/nte605a.pdf SK3864 also looks like a possible replacement.
  15. Ylli

    Marantz 2015 Receiver Distortion

    Two diodes in series - Your DMM may not have enough voltage to turn them on. Measure and post the voltage at J606 and J607 (and/or J620/J119 for the other channel).
  16. Ylli

    Marantz 2015 Receiver Distortion

    Both channels? Kind of rules out a random component failure. When you randomly replaced the caps, are you sure you didn't get any of the polarized caps in backwards?
  17. Ylli

    Where is the oscillator?

    No, that is not a tantalum. Looks to me more like this: https://www.digikey.com/product-detail/en/panasonic-electronic-components/ECW-FD2W224KQ/P16713-ND/4271854
  18. Ylli

    Where is the oscillator?

    0.22 uF 50 volt ceramic cap. A polarized cap is not going to work there. A 2n3904 is no where near equivalent to the 2sc3303. Find something closer.
  19. Ylli

    Switching a RF signal

    I'd suggest a Minicircuits part. So my post to you in the other forum,
  20. Ylli

    Help for component identification

    And looking at the circuit, I suspect U5 is a voltage regulator chip and these two caps (EC4 and EC5) are bypass caps for it. Looks like a 1206 size (measure the good one, see if it is 0.12" x 0.06") and I would think 10 uF would be good. As for voltage, just be sure the voltage is high enough...
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