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  1. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    Well, I don't think it's the relay,leave at alone for know. It has nothing to do with warming or cooling of the environment either. You most probably have an intermittent contact/device,your probing makes/breaks that contact . That is why the noise appears/disappears. I would focus on the...
  2. dorke

    Problem - Tuner amp AKAI AA 1175

    Welcome to EP. This is a very good vintage receiver ,absolutely worth repairing!!! Here are some things to for starters : 1. Are the LEDs operational? 2. Are the meters moving when the dial is moved ?(in FM with an antenna connected). 3. this unit has 2 main transformers,each with it's own...
  3. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    O.K. this kind of probe should do if connected to a "line in"(being greater than 10Kohm,as they are) of an audio amp. Impedance- meaning anything which isn't purely resistive(like your probe with a capacitor in it). It is indeed variable(frequency dependent) like your probe is i.e. blocking DC...
  4. dorke

    Flexible Shaft

    Your hand drawing skills are impressive:). I don't know if it is feasible here,but maybe an optical approach may be simpler. Using an "optical fork sensor" instead of the Hall sensor ,and instead of the magnet use a "light blocking attachment" bulging from the shaft (or a slotted disc type) ...
  5. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    Apart from the noise,does that channel work o.k? What kind of "audio tracer" do you use?(photos?) should have a DC block and I hope it's a relatively high impedance one, this is important for probing other parts of the circuit without damaging them. With a proper tracer you can compare the...
  6. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    The final stage is a push-pull "DC-coupled" output and differential amplifier input. Some possible problems : 1. You should clean the speaker relay contacts with Deoxit soaked paper,rub gently.(blue) 2. Another issue is the the differential amplifier input the 5 pin Tr.(red) Clean it's bottom...
  7. dorke

    Please help me find this FFC connector

    Welcome to EP. For connectors(any type), FFC check are: 1. Molex 2. JST 3. TE
  8. dorke

    Voltage Amplifier

    Hop, You are always a wealth of knowledge that comes with a lot of experience.:) If I'm not mistaken APEX was producing Hybrid RF Power Amps since the 70s(or earlier), they were the "go to guy" for quick RF solutions that work back than. Looks like they are still alive and kicking ;)
  9. dorke

    Rigol current probes?

    If it will do, Hantek has a 20KHz probe for much less.
  10. dorke

    Zero Crossing Point Detector .....

    I don't have personal experience with BDLCs. Thought these links may help you: 1.NXP 2.ST 3.TI 4.MicroChip1 5.MicroChip2 6.ATMEL 7. Infineon
  11. dorke

    MCS 3847 Integrated Amp Noisy Left Channel

    In my view replacing parts that way is a shot in the dark. These problems should be pin point located. This kind of faults are best located using a SCOPE,most people don't own one, so an audio signal tracer is the next thing to use,that can be DIY build. Since you have one good channel to...
  12. dorke

    Hacking the buzzerbox

    So, You can get about 9VDC or lower power from pins 1 and 4 (needs bridge rectifier+filter cap). What specific bluetooth module do you want to operate ? I note your measurements are not the same in different posts.
  13. dorke

    Replacements for ACST6-7S and ACS108-6S

    In that case look for same package TRIACs in your stock. If you have any post the part numbers ,we can check if they will do.
  14. dorke

    Volume control potentiometer is mute for first 10%?

    It can be a worn out pot,or a mechanical fault at the start. But if it is a new one that isn't very likely. Are you measuring voltages on the pot,or use your hears? Try to measure voltage or resistance. What do you get?
  15. dorke

    Help selecting my 1st DSO please.

    Apart from "hobby orientated", what are your needs in frequency/level and type of waveforms? In the audio range there are many excellent free of charge software driven Windows/Android waveform/signal generators with loads of possibilities. They work through the Sound card, so most are dual ones...
  16. dorke

    Designing a counter with an arbitrary sequence?

    Welcome to EP, you can post as much info as you think is needed to make the issue clear. The number is indeed 3 Flops.2 bits for the output and 1 to "help" transitions. Why doesn't it make sense to you? It is not clear, in what case do you need 5? And Yes a 5 bit Karnaugh map is possible to...
  17. dorke

    Need assistance identifying this component

    Welcome to EP, Please post a photo it would be easier that way.
  18. dorke

    Transistor Help

    Well Amigos, Obviously the correct switching element for this case isn't a BJT. Either use a Darlington or a Mosfet. A logic level Power Mosfet( N-ch. enhancement mode)being the best solution (a bit hard sticking to to-92 package,like the S8050). e.g. VN0106N3-G I would look for another part...
  19. dorke

    Audio speakers

    There are a few routs to take. Please answer thes questions,so we can guide you: 1. Why do you use 6V,what feeds it,why not higher? 2. What audio wattage do you need ? 3. What quality do you need?
  20. dorke

    3W LED dimmer

    Welcome to EP. The proper way to dim a high power LED is using PWM. There are various IC's that are tailored for this, and some cheap assembled modules well. How many Leds do you plan to have? Different control,common control? It is not clear. Anyways, forget about the resistors they are...
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