Sign in   |  Join   |  Help

Search

  • Re: B&O Test Equipment..

    You don't really need it! The SN15 service manual and an MC1466L datasheet/app note should more than suffice. There will be only minor differences in the output transistors and the MC1466-external current/voltage regulation resistors and you can easily figure them out by studying the MC1466 datasheet. If the MC1466L is busted you could try a fake chip from China (readily available via ebay) or if you don't trust them Chinese, why not just build your own! < see here > It looks simple
    Posted to The Workbench (Forum) by manfy on Tue, Apr 20 2021
  • Re: Beosound 9000 (Mk1) shows PWR Error 20 in testmode

    [quote user="69er"] I just don´t want to spend time on investigations other people already did. Sharing knowledge helps :-) [/quote] Oh yes, indeed. And this seems to have become the preferred approach to electronics repair, especially in the younger internet-focussed generation... Personally, however, I prefer a more pro-active approach and find it more expedient and beneficial at the end of the day. Anyways, so just let's wait til somebody who's had the very same problem
    Posted to The Workbench (Forum) by manfy on Sat, Mar 27 2021
  • Re: CD disc drive hub friction problem

    I had a similar problem on a DVD drive in my PC once. There's only 2 ways to eliminate slipping: A) increase friction on the hub that's attached to the drive shaft B) increase the clamping force by using a stronger magnet on the 'locking hub' (I'm not sure what's the formal name of that magnetic thinggy that presses the disc onto the drive hub) There are upsides and downsides to either method. If the additional rubber on the drive hub is uneven, you may introduce a wobble
    Posted to The Workbench (Forum) by manfy on Sat, Mar 27 2021
  • Re: Beosound 9000 (Mk1) shows PWR Error 20 in testmode

    [quote user="69er"] I can measure resistors, capacitors and transistors. Also exchange them. [/quote] You really have the equipment for and reasonable experience in SMT repairs?? I just downloaded the BS9000 service manual and it seems that most of the boards are surface mount. If you don't have the equipment and experience it would be a wiser (and probably cheaper!) choice to bring it to a professional repair shop. The unit is 20 years old and spare boards are probably hard to come
    Posted to The Workbench (Forum) by manfy on Fri, Mar 26 2021
  • Re: Beomaster 3000-2 LOUD buzzing noise?

    Hi Christian, In your utube it looks like the sound is coming from the unit itself and it seems that the buzzing noise is increasing in the first 5-10 seconds. Is this correct? If so and provided there are no speakers connected yet, my first guess is magnetostriction. That means an aging transformer with less than perfect coatings on the core iron laminates and/or windings is causing the buzz. Degrading rubber bushings intended to avoid transmission of those vibrations to the chassis can be another
    Posted to The Workbench (Forum) by manfy on Wed, Mar 24 2021
  • Re: Beomaster 1900-2 T2903 dead after recap

    [quote user="Andreas"] Since the stand by light never lit up, i hope the whole unit was never powered up in the first place. [/quote] Yes, exactly. I looked at the circuit diagrams again, trying to figure out the safest way to test the boards. The design is rather confusing and there's no way to measure every node on the 15V rail and I fear we may have to do one of those "let's see what happens" tests and just hope for the best. Here's what I would do if I had that
    Posted to The Workbench (Forum) by manfy on Sun, Dec 6 2020
  • Re: Beomaster 1900-2 T2903 dead after recap

    Eureka! I found the reason for your seemingly low 26 ohms on TP15: The volume indicator board 6 sits right on the 15V rail and provides a direct path to GND. Those 2 bulbs are spec'ed at 12V/1W, i.e. 144ohms. That is the resistance at operating point. Let's assume a cold resistance of approx 10%, i.e. 2x14 = 28ohms. Now your measurement of 26.x ohms at TP15 makes sense and you don't need to worry about too much smoke. In light of this new discovery, I'd say you can skip the step of
    Posted to The Workbench (Forum) by manfy on Sun, Dec 6 2020
  • Re: Beomaster 1900-2 T2903 dead after recap

    Congratulations! That went better than I thought. It proves that you've done a good job with your recapping works and we can be reasonably safe to assume that all will be ok with the power amp too. Here's the final steps: - unplug the unit and reconnect the wires to the 31V supply - keep the voltmeter connected to TP15 and GND because this will be our first adjustment - keep the speakers disconnected and turn the volume to minimum - plug in the cord and switch on the mains switch - bring
    Posted to The Workbench (Forum) by manfy on Sun, Dec 6 2020
  • Re: Beomaster 1900-2 T2903 dead after recap

    [quote user="Andreas"] I hope everything seems to be ok now, i'm feeling very tempted to turn it on but will wait for your last word :) [/quote] NO !!!! Do NOT turn on the unit !! You will fry your new TR27! Explanations: - you measured 2.8mV at the collector of TR27: The only plausible condition where this can happen (with 20V on the emitter) is if the 15V rail is shorted to GND. And that is a failure condition! The backplane of TR27, which I call the heat sink of the transistor, is
    Posted to The Workbench (Forum) by manfy on Sat, Dec 5 2020
  • Re: Beomaster 1900-2 T2903 dead after recap

    No, if TR27 is insulated now against GND then leave it as it is. But please do the comparative resistance measurements with the donor unit on all TP test points mentioned above, before powering on. Maybe also compare the zener diodes without removing them. That can tell us quite a bit.
    Posted to The Workbench (Forum) by manfy on Sat, Dec 5 2020
Page 5 of 14 (135 items) « First ... < Previous 3 4 5 6 7 Next > ... Last » | More Search Options
Beoworld Security Certificate

SSL