Search results

  1. elebish

    BT150 Thyristor equivalent(BT151) has just exploded !!!

    Motor control The scr will not change the output voltage by itself since it must be controlled. Some kind of control circuit must be employed to control the scr. Since most components are inexpensive, replace all ic's and check all resistors and caps. I would also check diodes including...
  2. elebish

    BT150 Thyristor equivalent(BT151) has just exploded !!!

    You must remember that the duty cycle of the pulses going to the motor determine speed and torque. Ed.
  3. elebish

    BT150 Thyristor equivalent(BT151) has just exploded !!!

    An scr allows current to flow one direction only when it is gated as long as the current flow through the scr is above the 'hold' current with voltages applied. It will stay on until it is reverse biased or until the voltages are removed from the scr. Hope this helps. Ed.
  4. elebish

    LCD TV Powersupply problem +Intro

    Just replace the board, probably cheaper in the long run and much faster. Sometimes we're the windshield and sometimes the bug! Ed.
  5. elebish

    Iwatsu SS-5711

    I also have a SS5711D scope with a similar problem that just developed. My problem seems to be in the Z axis circuit. Resistor 19R47 was open and replaced but still the same problem. A quick way to check those electolytics is to jumper them with like values and watch the screen. You might try...
  6. elebish

    BT150 Thyristor equivalent(BT151) has just exploded !!!

    Probably an "induction" motor. An scr is used to control the speed of the motor but the scr must be contolled by triggering the gate to turn on and then reverse biasing the scr or removing the voltage from the scr down below the holding current needed to turn it off. This will send pulsating dc...
  7. elebish

    What is this capacitor?

    On the 105, the last number '5' is the multiplier and the first 2 numbers are the basic value. It means to add 5 zero's, which makes it a 1 uf when counting back 6 digits (ufd) from 1000000. A '104' would be a .1 ufd, 103 would be a .01 ufd. Remember, when reading small values, use short leads...
  8. elebish

    Power inverter output too high

    Switching type PS's are a pain to work on because of the frequencies used to keep the transformer (terroid) sizes down and therefore the cost. They also use a pwm (pulse width modulation) circuit to regulate the output voltage. You will need a scope to look at these pulses to effectively T/S the...
  9. elebish

    component identification aka resistor?

    csmith is correct. Resistor values in that circuit are critical and do not use a wirewound resistor as those will create an impedance (inductance) with ac being applied. This is especially true when the PS is a switching type. Ed.
  10. elebish

    audio bleeding between channels in the power amp stage of a mixer amp

    Many amps use "op amp ic's in the pre-amp section. Usually, they use dual op amps to save costs. One of these could be internally or externally shorted or could have some solder flux connecting joining pins if the amp has been worked on lately. Some solder fluxes made today are substitutes for...
  11. elebish

    Repairing power supply for fun

    If the cap is blown, you probably have a shorted power supply diode feeding ac directly to the cap. Many of those diodes are a bridge type. If any ohm checks (use diode mode) checks shorted, replace. You might also check for shorted MOV's or other safety components used. Ed.
  12. elebish

    trouble shooting - first try with electronics

    Most of these devices that have heating elements, usually have thermal switches that turn off when too hot. That happens when unit is on with no water in reservoir. Most also have a small temperature "fuse" with the temp marked on it. If that is opened, replace it with same type. Check the...
  13. elebish

    Help with replacing component on circuit board

    Good advice Duke! Ed.
  14. elebish

    Yamaha reciever power issue

    Ensure that the total speaker impedance is NOT less than 3 ohms! Ed
  15. elebish

    Yamaha reciever power issue

    Check the emitter (thermal runaway) resistors. They are usually about a half ohm at several watts. I would also check the driver transistors. The "clicking" is usually a protection circuit that shuts down the power supply when something shorts out. You might try putting a 75 or 100 watt...
  16. elebish

    Hitachi tv convergence issues

    The most common problem with (what looks like a convergence problem) is the demodulator modules. They are large multi pin chips mounted on a big heatsink and there are usually 2 of these that cover the 3 colors. Along with these are several low value resistors that usually open when these...
  17. elebish

    Iwatsu SS-5711

    If you are referring to the p/n ISS16 (D32) as listed on page 19 of the Z axis schematic, that diode is a schottky for fast switching of the unblanking pulse. It has a fwd voltage drop of only .23 volts. I have an Iwatsu SS5711 D scope and also have a focus problem. I found R47 open which is in...
View older results
Top