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  1. dorke

    Memory investigation on an HP35665A and bad desoldering

    Well, It sure can scorch the print,but that means you haven't used it correctly. You should use it at a distance of about 3-5cm , and more importantly, keep moving it constantly along the pins till the solder melts. Adjust the temperature to the lowest needed, I try to go with 290c and with...
  2. dorke

    Memory investigation on an HP35665A and bad desoldering

    Steve, The job of removing sip chips is a job tailored for a hot air gun, once you use it ,you will fall in love with the ease,simplicity,time saved and quality of the results. A must have if you are dealing with SMD, but also great for through-hole devices. Here is the one I use, it is a great...
  3. dorke

    Diode Identification Help

    What is the voltage rating of C9(left of D4) ?
  4. dorke

    Bass Amplifier troubleshooting

    Try measuring the DC voltage on the speaker,you should get 0v. The +rail is too low if you are getting +40v(should be +57). Measure the AC volt on the +rail and compare it to the -rail.
  5. dorke

    Need help finding a replacement transistor?

    The part to the right of that 2SB826 looks like a relay. In this case you should check the diode seen behind the 2SB826. Driving relays and motors (inductive loads) makes life "miserable" for transistors and they need help/protection. In general you can replace a part with a different one with...
  6. dorke

    Oscilloscope: screen seems dead

    to Dave, It easier to disconnect the board from the back of the CRT and measure with scope disconnected from mains the 6.3vac winding resistance... In general, as a first step in that kind of fault: I would look for the filament light from the back/neck of the CRT and if not visitable...
  7. dorke

    Diode Identification Help

    Here it is D4:
  8. dorke

    Diode Identification Help

    2SK3564 is a 900V/3A/40W power MOSFET for switching regulators. I do believe the diode is a shotcky one, But I can't identify it.
  9. dorke

    Diode Identification Help

    By the marking on the board it is a diode,and it sure looks like one. In my experience,the 1N400x diodes are always marked with their full part number on them. Since it is located near T2 and Q11 it may be a fast switching power diode(shotcky?). If so,replacing it with 1N400X is not a good...
  10. dorke

    Help on how to test this device

    Hi HellasTechn, This design seems to lack any "PWM control". That is why I think it is a bipolar transistor and not a MOSFET...
  11. dorke

    Help on how to test this device

    I don't think it is worth repair! U1 is a voltage reference/regulator (TL431 like) OP1 is an opto-transistor IC1 is a power transistor, I think it is probably Bipolar and not Mos. The circuit looks similar to the flowing design
  12. dorke

    Philips bike-light, blown up element with two connectors: BDP 06A

    The device is a transient voltage suppressor (TVS). I think it is there to protect against voltage surges from the dynamo. If that part is blown, it may very likely be that something else on the board went bad as well. It is a part manufactured by General Semiconductor which is now owned by...
  13. dorke

    Help on how to test this device

    What you have is a direct mains SMPS. They have dangerous AC/ DC high voltages in them.that can kill you ! What is written on IC1,U1,OP1 ? Yours is a junk,a very bad quality item(even new)! Buy a new one of better quality,they are cheap. You can start learning about them here...
  14. dorke

    ELECTROLUX washing machine schematics-Service Manual

    My uncle's washing machine stopped working. I haven't seen it yet, before I try fixing it for him I would like to have the service manual or schematics. I couldn't find it on the web, can anyone help with it? (a similar model could also help, It is a front loader ) Thanks Electrolux Model EW...
  15. dorke

    Help on how to test this device

    Alec_t is correct-see enlarged photo I wouldn't bother with that "junk". BTW,It looks such bad quality anyways-get a new one.
  16. dorke

    Join two or more power supplies together - create quad output

    Hi Marcus, In general,you can combine different power supplies to get the needed number of outputs. In this case I wouldn't recommend that you do! The best solution is to get the exact same original part from Electrolux,it may be a bit more expensive but worth it... Is it a hard to get part...
  17. dorke

    What language is this Receiver Displaying?

    What Language? Gibberish! If the receiver's only fault is the things it displays on the FL, than the problem is the connection of the FL display to it's driver. Perform the built-in FL check(see attached file from the SM). You could do the following as well: Open the receiver carefully...
  18. dorke

    Yamaha Home Theater Receivers woes

    As for the Yamaha RX-V494: "PS" in the Yamaha jargon means "power supply DC fault",the value is the "deviation amount from normal" . You have to get a service manual and check all DC voltages in the unit(there are quite a few ...) There is a way to disable the the shut-off ,you should look at...
  19. dorke

    Siemens waching machine Siwamat plus 7421 repair-need schematics

    Problem fixed-machine is now working. The fault was the door-interlock(door switch). It is a 4 contact one (YMOS part): pins 1-2(PTC) get the 220volts and close the connections 4-5(switching the Neutral line). Since I couldn't get the schematics of the machine ,I had to trace the...
  20. dorke

    Power amp fan trouble

    The schematics Martin posted seems to be missing the path to the FAN from the sensor. I found other schematics which have holes in them but together may give he full picture(jpg simplified drawing). The path then goes to the Arlington driving the FAN itself on the power supply schematic location...
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