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  1. dorke

    Amp keeps going into protection mode

    O.K. Please mark that point on the "dial". Now open D10 (cut it like you did for D8). With both D8 and D10 open,does the amp go into protection?If it does, at what point? Measure with the DMM in "diode mode test" D8,D10 and invert polarity, what do we get?
  2. dorke

    Amp keeps going into protection mode

    Rick could you please "re-open" diode D8, like in #77. Does the amp go into protect?
  3. dorke

    Cyclic Redundancy Check Circuit

    Yes ,there are many kinds. Look here and this can help you
  4. dorke

    Cyclic Redundancy Check Circuit

    Which specific CRC are you interested in?
  5. dorke

    How to find this component

    Here is one ,may not be the correct number of pins or length but that is the basic thing you need
  6. dorke

    Soldering and veroboard HELP!!

    A side note: Not all metals are solder-able with solder wire.
  7. dorke

    Amp keeps going into protection mode

    Rick , The diode tests we did are incomplete for the reasons explained in #122. In order to get to a conclusion about the diodes, we need to have them marked correctly on the schematics. Use an ohmmeter in 20K range to measure resistance between R2,R3 and the diodes,to find the way the diodes...
  8. dorke

    Amp keeps going into protection mode

    O.k. This is fine. It is 99% certain that the problem is with the capacitors(one or both). You should get 2 new ones of low ESR type and solder them . Remove the jig and re-solder the cut wire.
  9. dorke

    Amp keeps going into protection mode

    You can try with the switch closed as well.
  10. dorke

    Amp keeps going into protection mode

    It is most likely that the capacitors are faulty one or bot Is the voltage produced by the batteries "at the 2.2K resistor" 3.25V ? Are the batteries connected in series?
  11. dorke

    Amp keeps going into protection mode

    Well, it looks like the batteries are (EDIT)NOT connected properly,they should be in series to produce the 3.25V as in #105. Could you please check that again.
  12. dorke

    Amp keeps going into protection mode

    I tried to understand why we get such confusing readings from the diodes. The answer is the schematics and the actual PCB are in disagreement ! 1. In the schematics the diodes that have their anodes connected are D9 and D10 while in the PCB they are D8 and D11. 2. In the schematics the...
  13. dorke

    Amp keeps going into protection mode

    Fine the last test: Same "reverse " connection of the Jig as in #118. Use two batteries and the 8.2K not shorted (open switch). The amp should go into protect. What are the voltages on R2 and R3?
  14. dorke

    Amp keeps going into protection mode

    O.k that looks fine. Now let's do the test with a single battery same conditions(8.2k shorted). only reverse the jig connection ,between S1-5 and the speaker black. The amp shouldn't go into protect. What are the voltages on R2 and R3? like that:
  15. dorke

    Wiring a Fire Bell to a flip switch?

    Any SPST N.O. (fancy technical for 2 pins normally open ) panel mounting one will do . Any door bell switch will do as well. You need to decide if it is momentary contact one (I would chose that here)and the size shape and color of the button. see examples here and here
  16. dorke

    Stereo receiver cutting randomly in and out

    Yes these are the relays. They sure are electromechanical. There are 3 "audio" relays in that Sony model(RY781,RY782,RY783). Ry781 is the earphone one. Do they all have the same part numnber? Do you have a digital scope or at least a DMM? Do you know how to solder/replace components on a PCB?
  17. dorke

    Stereo receiver cutting randomly in and out

    When it cuts out ,do you hear a relay clicking? Try "taping" the board with no input signal,it will make it easier for you to hear the relay click if present. Have you looked at the flat cables connecting the main board and the display front panel board? Look for cable tilted or not fully...
  18. dorke

    Detecting positive and negative edges

    Rajinder, It would be the best ,if you can show us the signal on a scope. So we can see it's shape,amplitude,edges etc. Can you do that ?
  19. dorke

    Amp keeps going into protection mode

    The 1N969 is a 22v zener diode,no good for us. The reading on R2 of 0.8V suggest that the switch (on the jig ) parallel to the 8.2k resistor is open. Could you please close it (short the 8.2K resistor) and repeat the test.
  20. dorke

    Amp keeps going into protection mode

    I wrote this: "So, Voltge on R3=1.09-0.53=0.56, not 1.10v like in post #110" It should have said post #107. The voltage on R3 at #107 is too high ,this is what had to be explained. Now it is ,it was not the voltage on R3 rather the voltage on one of it's legs. So we have voltage on R3=0.56V...
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