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  • Re: Troubles with tuner in Beomaster 5500

    To be honest, I've never serviced either of them. My answers are based on theory and the service manuals only. The 8032 is fully backward compatible to 8031, but it has more RAM. So it is thinkable that hybrid versions exist, I guess. I'd say there's one way to check which test mode procedure to follow. The 5500 manual says that the ROM 4IC4 is an 8x16kbit ROM on the 8031 processor, the 6500 manual shows a 8x64kbit ROM on the 8032. A bigger ROM suggest a more elaborate firmware and more
    Posted to The Workbench (Forum) by manfy on Fri, Jun 4 2021
  • Re: Beomaster 1500 - DC offset problem

    Is that a trick question? If you pick just any transistor with arbitrary gain values and voltages, one would surely expect that the output is different than with original transistors, don't you think? Do you think that the B&O guys picked the BC547B and the BC182C for this opamp TR104/105 just to annoy you? (see footnote) I would guess they did it on purpose and for some technical reason. Either they actually calculated the amplifier design or - more likely - they used a standard design and
    Posted to The Workbench (Forum) by manfy on Tue, Jun 1 2021
  • Re: Beomaster 1500 - DC offset problem

    In the Fairchild datasheet I see following: BC547B: hfe = 200-450 BC547C: hfe = 420-800 So yes, I'd consider that a substantial difference. I didn't find any datasheet on BC182C, but BC182 has 125-500 gain. That is also quite different from 420-800. You said that the transistors installed initially were all 547C. Did they seem factory-assembled or were they changed by some repair guy? If they were factory-assembled, I'd stick with the same models. 15mV instead of 10 doesn't seem critical
    Posted to The Workbench (Forum) by manfy on Tue, Jun 1 2021
  • Re: Beomaster 1500 - DC offset problem

    Oh goodness! I just realized that you talked about the DC offset on the speaker terminal, but I've been thinking of the 10mV setting of the idle current all along! So, sorry for that! I deleted my reply to avoid further confusion. In any case, I still agree with Martin. Granted, 0V at no input signal is the ideal value for a distortion-free output signal, but a minor DC offset of 25mV is quite certainly not audible. In the service manual it shows a value of 0V +/-200mV at the speaker output.
    Posted to The Workbench (Forum) by manfy on Tue, Jun 1 2021
  • Re: Beosound Ouverture CD, ratchet and backwards spin

    [quote user="Martin"] At least one other thread ( https://forum.beoworld.org/forums/t/284.aspx ) mentioned that the large caps could cause problems without specifying them. But considering that sometimes really strange behaviour can be seen, do you think it is worth spending time on trying to find and replace the caps anyway? [/quote] That thread doesn't sound overly convincing, but yes. Your picture shows that the board version is from 1995 and if that's close to the manufacturing
    Posted to The Workbench (Forum) by manfy on Fri, May 28 2021
  • Re: Beosound Ouverture CD drive types interchangeable?

    [quote user="Martin"] Reading about the mechanisms, it is my impression that the CDM4s are a lot less error prone - save for the infamous capacitor, but that is at least an easy fix. [/quote] Far be it from me to talk you out of it! Sound quality is something like a religion to some people -- in fact for me too. But in the end it's a very subjective thing and you should go with what suits you best. The CDM12 Industrial has a very good reputation, so it's nothing to look down at
    Posted to The Workbench (Forum) by manfy on Thu, May 27 2021
  • Re: Beosound Ouverture CD, ratchet and backwards spin

    [quote user="Martin"] The strange thing is that it does not happen all the time. Only when selecting the first couple of tracks. So it does feel a bit unlikely that the clock signal could differ depending on laser position. [/quote] Yes, I know - it's not the first thing that would spring to mind when you see your symptoms but an intermittend contact problem (be it a cold solder joint or whatever) can cause the strangest problems! I did download the service manuals for the Beosound
    Posted to The Workbench (Forum) by manfy on Wed, May 26 2021
  • Re: Beosound Ouverture CD drive types interchangeable?

    Yes and no. If you look at the last page of the Beosound service manual for the CDM12 version, you see the changes they made. CDM 4 needs -5V and if your system was made for the CDM12, your power supply may be missing those parts (12R113, R23, C61, D7 and TR2). But why would you want to install an old CD mechanism? (Unless you have a known good CDM4 idly lying around somewhere, of course.) CDM4 has its own problems. Did you replace the CDM12 yourself? Was it a brandnew replacement unit or a used
    Posted to The Workbench (Forum) by manfy on Wed, May 26 2021
  • Re: Beosound Ouverture CD, ratchet and backwards spin

    I looked at your uTube video again and started studying the circuit diagram. There's no technical and justifiable reason to turn the disc backwards. So it's safe to assume that something is seriously wrong there and that this needs to be addressed before moving forward. There are only 2 parts that affect the spindle motor: IC7003, the decoder chip with the motor control circuitry and IC7002, the driver IC. If I were in your shoes, I'd do following: 1) measure the drive motor voltage;
    Posted to The Workbench (Forum) by manfy on Wed, May 26 2021
  • Re: Beosound Ouverture CD, ratchet and backwards spin

    [quote user="Martin"] My first thought was that the laser carriage end position switch engaged to late, causing the laser motor to try to move it too far but I cannot find anything mechanical suggesting that this would be the case. It engages only at the very top millimeters which would not be reached when trying to play track 2 or 3 for example. [/quote] Well, no. No matter where that switch is located within the physically accessible range of the sledge, it shouldn't make that noise
    Posted to The Workbench (Forum) by manfy on Wed, May 26 2021
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