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  1. dorke

    Amp keeps going into protection mode

    Wow,this is confusing,hard to read. looks like you have replaced anode and cathode. this is the notation: "D9, Cathode side reads 1.10V D10, Cathode side reads 1.10V" D9 and D10 have their anode in common not their cathode . and likwise: "D8, Anode side reads 0.53V D11, Anode side reads...
  2. dorke

    Amp keeps going into protection mode

    Rick, As it is looks like D11 is shorted(1.54-1.51=0.04V.) Please confirm the voltage on it directly -both probes on it. Other measurements don't comply with each other for example the voltage on D8 looks "reversed" ,and there are more like that. Could you please check the voltage on the...
  3. dorke

    Amp keeps going into protection mode

    That is not what I'm expecting ,voltage on R3 is too high. While in protection mode, please check the following voltages: The batteries. Each of the 2 resistors of our Jig (2.2k and 8.2k). The voltage on the diodes D8-D11(black on the black line of the diode side-the cathode) . The voltage on...
  4. dorke

    Amp keeps going into protection mode

    Please measure the voltage on R2 and R3 in the protection mode.
  5. dorke

    Amp keeps going into protection mode

    It will prove that in "DC conditions" the protection circuit works as it should. This "DC condition" is achieved by the strong filtering effect the suspected caps have. If they fail ,the AC signal at the output will "reach" the protection circuit and trigger the protect mode.
  6. dorke

    Amp keeps going into protection mode

    As you said :"I have two 2k resistors, an 8.2k, and a 2.2k resistor" We shall use them for checking. First thing is to re-solder the diode D8 Leg. Leave the S1-pin5 wire cut! 100uF caps out of the PCB as it is now. Build this little circuit, if you don't have a switch, a wire can be fine. If...
  7. dorke

    General questions regarding transistors in different modes.

    1. Yes ,to be more precise ,it also depends on VCEsat which is transistor related. 2.Yes,but to be more precise that absolute max IC is constant(DC) current.
  8. dorke

    Amp keeps going into protection mode

    Yes most likely. On 2nd thought we can do another test with a small jig. Do you have 2 AA or AAA 1.5V batteries? And Some wires?
  9. dorke

    Amp keeps going into protection mode

    I guess assume the caps are faulty. Buy new ones and put them in, then re-solder the cut wire and try the amp. The caps should be low ESR type(lately also called "computer grade""). Have you got a store near you that may have them? And don't forget to clean the PCB.
  10. dorke

    Amp keeps going into protection mode

    Yes ,it should be fine. Maybe it doesn't touch well, try jiggling the cap in the socket.
  11. dorke

    Amp keeps going into protection mode

    Here is the manual of your DMM Are you using the CX socket? You should use the outer most contact points. I guess one cap leg in one of the 3 upper holes and the other in one of the lower 3 will do.
  12. dorke

    Amp keeps going into protection mode

    The polarity doesn't mater. Simply put the DMM in the 20u F(one position cw from the off) range and read the result. Start with measuring the 10uF you have,so that we know the meter is working in the F range. What does the 10uF read ? What do the 100uF read? What other caps in the range of...
  13. dorke

    Amp keeps going into protection mode

    In the CX socket . If the leads are too short, you should use "extension wires ",improvise something. The PCB needs good cleaning ,use a cotton swab and rubbing alcohol. Do you have any cap with value just under 20uF?
  14. dorke

    Amp keeps going into protection mode

    O.K it is fine. We are left with the capacitors C6,C8 100uF each ,they should be low ESR type In order to check them we should use a capacitance meter and/or an ESR meter. You do have capacitance checking on your DMM but the max range is 20uF no real help here,(but we may get lucky if a cap...
  15. dorke

    Amp keeps going into protection mode

    O.K. For now leave D8 open as it is. Please check the resistance between each speaker red(+)terminal and the wire we have cut from connector S1 . Do it on the wire side connected to the main amp board (not to the S1 side of the cut). DMM in 200K ohm range. that is a total of 5 measurements...
  16. dorke

    Amp keeps going into protection mode

    O.K Please check R3 in diode mode with flipping(with D8 leg lifted) . Rick , you didn't answer my question about your PCB soldering skills.
  17. dorke

    Amp keeps going into protection mode

    Diode D8 is fine. With the leg of D8 lifted ,please check the diodes D9-D11, in diode mode and flipping probes.
  18. dorke

    Amp keeps going into protection mode

    Please check on the PCB pads of D8(with the diode leg lifted as in #78).
  19. dorke

    Amp keeps going into protection mode

    Looks like we found our bandit...D8. Please confirm it's measurement's (comparing to the other diodes). If they confirm you should cut a single leg of D8 (in the middle as shown,so that if needed it would be easy to solder it back), lift the leg a bit and recheck D8. I hope your cutter is fine...
  20. dorke

    Amp keeps going into protection mode

    O.K Lets test the diodes D8-D11 , DMM in diode test mode and flipping the probes on each diode. Have you got a 4.7K or about resistor? How are your soldering skills(on PCB,any experience with that)?
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