Search results

  1. dorke

    7240PE Q427, Q428, Q429, Q430 - part substitutions

    Well, You shorted the speaker terminal to ground that destroyed the PA channel, efficiency of protection circuits and fuses... anyone? The tuner works since the short was caused by the shield of the coax. Anyways,the input of the tuner has a blocking DC cap. which provides some protection as...
  2. dorke

    Automata clock. Running a motor for 30 second each hour.

    You would probably need a " programmable 24hours digital timer ". There are many on the market ,most of them can provide 1 minute resolution, if you can live with that(not 30 sec) then you have your medicine ready made . In any case look here ,needs more investigation for the small details...
  3. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    Edd, There is a photo of the print side(#21),no need for eagle eyes... a "blind bat" can trace it better;) Lifting C203 was intentional (although pin 7 was indeed my first choice! ) 1.Easier to do and replace,(square old pin and wire) and been done before on this board. 2.No need to isolate...
  4. dorke

    Problem - Tuner amp AKAI AA 1175

    Mike ,Your welcome.:) Hope the repair cost will be reasonable.
  5. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    Dear Edd, The input circuit to the PA looks like below(drawing made from the PCB traces). Removing C203(not C201 !) totally isolates the PA from the feeding circuit. The test shows no noise at the input to the PA(at the right tip of R201), with noise at the output of the PA (speaker) . That...
  6. dorke

    Automata clock. Running a motor for 30 second each hour.

    Are these times fixed?(i.e no need to change the periods) What accuracy do you need for each? It is a simple task which can be achieved in several ways. The best would probably be to use a small micro controller chip. You would need to make a small μC circuit(or purchase a ready made one), And...
  7. dorke

    Thyristor question

    The Thyristor will be just fine, why do you think it may be harmed if it turns off? And yes,there is a holding current(there always is in the datasheet!). Once you have triggered the thyristor, for it to stay on (regardless of the gate state), you should keep it's current(IT) above IH =20mA.
  8. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    Measurements for TR201 and TR202 are with black probe on chassis ground and red probe on each of the legs. That means voltage relative to chassis ground. Measurements for the resistors are all with both probes on the resistor itself(difference between both legs of the same resistor). Sorry if...
  9. dorke

    Unknown plug needs replaced

    There is a TQ company,the relations to the motor you have is unclear. May worth contacting them(via the support on there site) for help,with low probability of success. Another way is to try and find the connector manufacturer (on male or female,disassemble if needed),that may provide a valid...
  10. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    Trying to put # and #41 together: The voltage drop between the two bases. TR210 and TR212 Without the noise: 2.41V TR209 and TR211 Without the noise: 2.398V If you're wanting the actual voltage. TR210 and TR209 are around 1.2V TR211 and TR212 are around -1.2V With noise: TR210 and TR212...
  11. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    "We have a result! No noise on R201, but there was an avalanche of noise on the output." So the noise definitely comes only from the PA, not from anything before it !!! Looking at TR201 there is something suspicious around it. Look at the REd area there is a "yellowish residue" area and what...
  12. dorke

    Problem - Tuner amp AKAI AA 1175

    Yes ,that should be a 9V battery. Better open it up before you go,in case there is an old leaking battery inside...
  13. dorke

    Unknown plug needs replaced

    Never seen that kind of plug. It may help if you know the make and type of motor.
  14. dorke

    Problem - Tuner amp AKAI AA 1175

    Is your meter like this generic one? If not, google "RAPITEST Multimeter" and look for it in the images search ,then link to it. You can learn how to use a basic DMM here , concentrate on voltage measurements and ohm/diode/continuity. For more in-depth look here
  15. dorke

    Problem - Tuner amp AKAI AA 1175

    Well, With some photos (of tour Multi-meter too) we can try to guide you further. Otherwise it is a job for the repair shop. addendum : What is the model and make of that Multi-meter?
  16. dorke

    Problem - Tuner amp AKAI AA 1175

    Mike , That electronic switch is actually elctromechanic ,it is called a relay in our lingo. It should switch on (and make a "click sound"). If it doesn't,it means the unit recognizes a fault condition or there is a general fault at it's power supply. What you can do is put the speakers switch...
  17. dorke

    Help with a connector (Newb Question)

    You have a 2 IC implementation : the controller is actually the Samsung KS0066F and the display driver is the Hitachi HD44100. Since the interface (14 pins) is the same, nothing will be blown up or damaged. The problem would manifest itself by wrong/garbled characters displayed. It is a...
  18. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    I'm more interested in the "net difference voltage" between the bases of TR209 and TR211 with noise. Please remove C203 as per post #34, what happens?
  19. dorke

    help -- muh logic ended in ruins

    O.K. For learning, they are good. But I wouldn't build any real word thing with them. With the exception of Oscillators. The only one I have ever used was the 74HCU04. There is another important issue to learn: why buffered vs. un-buffered gates. Read this it will help you a lot. You should...
  20. dorke

    T8 - LED shop lighting

    I paid about 4$US for each LED bulb(not the filament), that is about 4 times the price of an incandescent one. Still looking for good LED replacement for halogen(300W) RS7 types.
Top