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  1. bertus

    Missing resistor in a voltage divider network

    Hello, The LM3914 is not a VU meter, it is linear. The LM3915 is a 3dB step meter. The LM3916 has a VU meter arrangement. Bertus
  2. bertus

    DIY RC Filter replacement

    Hello, The RC combination is likely to be a snubber circuit. The wiki has some info about the snubber circuits: https://en.wikipedia.org/wiki/Snubber I have also attached a PDF with some theory on snubber circuits. bertus
  3. bertus

    Antique "Acoustic" amp needs attention ASAP

    Hello, What happens when you plugin a sound source into "power input" ? The sound might be a low level, but you can see if the power amp is working. Bertus
  4. bertus

    DIY RC Filter replacement

    Hello, The circuit will be likely less effective with the 0.033 uF in stead of the 0.1 uF. They will have a reason why they use the 0.1 uF. Bertus
  5. bertus

    Antique "Acoustic" amp needs attention ASAP

    Hello, There are 6 diodes on the powerboard. I do not think the diodes are bad. What is happening with the amplifier? Bertus
  6. bertus

    Antique "Acoustic" amp needs attention ASAP

    Hello, When those capacitors go bad, the electrolyte will likely pour out at the side of the rim, now close to your fingers. A lot of information on capacitors can be found on the CAPSITE: http://www.iequalscdvdt.com/ Bertus
  7. bertus

    Antique "Acoustic" amp needs attention ASAP

    Hello, The brown blocks are the coils in the equalizer. Bertus
  8. bertus

    Antique "Acoustic" amp needs attention ASAP

    Hello, According to this site, the 220 and 126 have use the same boards: https://music-electronics-forum.com/showthread.php?t=40880 You can download the 220 schematics from that page. Bertus
  9. bertus

    DIY RC Filter replacement

    Hello, The resistor/capacitor combination is likely to be a snubber or "spark quencher" circuit as metioned on the following page: http://www.iequalscdvdt.com/Line-filter.html As @Harald Kapp said X rated caps should be used. I even think a X2 is recommended. Bertus
  10. bertus

    Larry Tesler , the inventor of copy-and-paste , dies at age 74

    Hello, The inventor of copy-and-paste has died at age 74: https://appleinsider.com/articles/20/02/19/larry-tesler-who-showed-steve-jobs-around-xerox-parc-dies-aged-74 Bertus
  11. bertus

    Hello

    Hello, Depending on the question you could post it in the following forums. If it is a general question, in General Electronics Discussion If it is a repair question, in Troubleshooting and Repair Bertus
  12. bertus

    Regulating voltage made it worse???

    Hello, What shape is the solinoid? Perhaps a shielding around the solinoid might help. Bertus
  13. bertus

    Common Emitter Amplifier - Class B

    Hello, Indeed the shown amplifier is not a real class B amplifier. The class C has no bias: https://www.elcircuit.com/2011/04/class-c-power-amplifier.html Bertus
  14. bertus

    Common Emitter Amplifier - Class B

    Hello, Have a look at this page for class B for RF and push pull audio: https://learnabout-electronics.org/Amplifiers/amplifiers53.php For RF circuits Class C is more common used: https://www.circuitstoday.com/class-c-power-amplifier Bertus
  15. bertus

    Common Emitter Amplifier - Class B

    Hello, The following page will tell you more about the amplifier classes and the related conducting angle: https://www.electronics-tutorials.ws/amplifier/amplifier-classes.html Bertus
  16. bertus

    Mac tools em710 component I'd help please

    Hello, Did you look for manuals? http://www.manuals.group/results.php?search=MAC%20TOOLS%20EM710 Perhaps in the service or schematics manual, you could find a value. As you need to enter an email address, I did not download it. Bertus
  17. bertus

    Tektronix 7844 Power supply issue

    Hello, Do you have the service manual? if not, you can download it here: https://bruce.edebris.com/manuals/tek/7844/ It might give you some hints. Bertus
  18. bertus

    Questions lithium polymer battery

    Hello, You never gave any info on the charge states that belongs to the number of bars. We can only guess what the bars could mean. We can not give a solid advice without the info. My opinion is that this thread has run its cause. Bertus
  19. bertus

    Common Emitter Amplifier - Class B

    Hello, Basicaly the OP made a class C amplifier. Only the signal that is high enough would open the transistor passes through. https://circuitdigest.com/tutorial/classes-of-power-amplifier-explained http://qooljaq.com/Amplifier_Classes.htm Bertus
  20. bertus

    Mac tools em710 component I'd help please

    Hello, When it is a PTC, it could be used as an auto resettable fuse. In these pictures you will see a lot of versions...
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