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  • Re: Beomaster 1000 model 2318 repair project

    Oops, sorry. Now I get it. First you tested an unused diode and that one seems to be ok. Then you tested the Zener in-circuit and you get 0.6V in forward and reverse direction. Since the resistance test between zener cathode and emitter is wrong, we can be sure that there's something wrong with this zener. Remove it and test it outside the circuit. If damaged, mount a new one and pay attention to polarity. The cathode must be connected to BC154 emitter as you see in the circuit diagram. rgds
    Posted to The Workbench (Forum) by manfy on Mon, Mar 9 2020
  • Re: Beomaster 1000 model 2318 repair project

    I ran a quick simulation on LTspice earlier and it seems if only the zener diode is mounted wrongly, you would get quite different voltage readings. However, if the collector-emitter section of BC154 is shorted out, the voltages I get look very similar to what you posted earlier. You should probably do a diode check on BC154. That's quite easy since a transistor acts like 2 diodes (for testing purposes): So, if you get anything but OL/OR (overload/over range) in diode test/resistance mode between
    Posted to The Workbench (Forum) by manfy on Mon, Mar 9 2020
  • Re: Beomaster 1000 model 2318 repair project

    [quote user="AntonvZ"] Cathode of Zener diode 908 reads 40.6V (I have already replaced this with a 9.1V zener diode) BC154 C=41.2V E=41.2V B=39.2v BC140 C=41.5V E=41.5V B=40.8V (I have already replaced this with a BC141 transistor, closest match) Trimmer Leg connecting to 470 ohm resistor #905 =39V, Leg connecting to 2.2K ohm reads 15.64V. Single leg side reads 39.2V and adjusts to 15.64V if you turn it.[/quote] Thanks! That's helpful. At first look, I'd say you mounted the new
    Posted to The Workbench (Forum) by manfy on Sun, Mar 8 2020
  • Re: Beomaster 1000 model 2318 repair project

    Just to make sure we're talking about the very same thing: You have a BM1000 type 2318. Martin said that it uses the same board and design as 2317. So, I copied the power supply from my 2317 service manual and added the nominal voltages in blue. All my posts and suggestions are based on this specific circuitry below. Some important notes about the voltages given: - the ground symbol (which normally represents 0V and often connected to the chassis) is positive in this design!! - if you connect
    Posted to The Workbench (Forum) by manfy on Sun, Mar 8 2020
  • Re: Beomaster 1000 model 2318 repair project

    [quote user="AntonvZ"] [quote user="Dillen"]"Stereo bulb 39V going in 9V coming out." - With 30V across a 18-19V lamp, it must be lighting up the whole village?[/quote] Indeed, a whole new feature, the way it brightens and dims depending on the volume setting is escpecially entertaining. [/quote] That is a good sign that your 2N5034 (now 2N3055) doesn't regulate at all. The volume setting changes the current drawn and the 30V supply goes down accordingly. Check the
    Posted to The Workbench (Forum) by manfy on Sat, Mar 7 2020
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