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  • Re: Beosound Ouverture CD, ratchet and backwards spin

    Hi Martin, I remember that "backward spinning" from a blog I came across a while ago. There one member said this: If it's a Philips based chip set then the D/A or the Digital Filter IC produces a clock which is fed back to the servo processing IC's which is where the Spindle Motor Drive originates. The signal used to be called (on older units where I have had this fault many times, apologies for not thinking of it !!) MC. If this clock goes missing then the Spindle Motor doesn't
    Posted to The Workbench (Forum) by manfy on Tue, May 25 2021
  • Re: CD 5500 repeat plays?

    Sorry, I couldn't help more! Here's a short recap for future readers who plan to hack the CD player control commands (and corrections to some of the things I said above): *) Forget about trying to read or copy the original programming from the CPU's MAB8441 and MAB8641 -- you can't. Both chips are mask-programmed, ie. ROM programming is part of the manufacturing process, and you can't access the ROM from the pins. ROM can only be accessed on the 40pin version of the chips, which
    Posted to The Workbench (Forum) by manfy on Sat, May 22 2021
  • Re: CD 5500 repeat plays?

    [quote user="ummagumma"]Thx for the input! I thought I'd read here it was based on a standard Philips CD player. Maybe it is just the transport [/quote] Well, in a way, every CD player is pretty much built like the first Philips player. You have the control circuits for the CD drive motor and the laser focusing and positioning sytem, which is part of the laser pickup or the complete CD-mechanism subassembly. Behind that there's the decoder, D/A converter and pre-amp and then one
    Posted to The Workbench (Forum) by manfy on Thu, May 20 2021
  • Re: CD 5500 repeat plays?

    [quote user="ummagumma"]Well I was hoping there was a voltage location I could jumper or add a switch to, to get it to restart the playback [/quote] No such luck, I'm afraid! If you look at the block diagram in the service manual, you can see that the DIN socket used for datalink with the controller goes to the MAB8461 controller. That means all start, stop, fast forward, etc commands are being processed by this uProcessor. You can also see an I2C link to the MAB8441, which is basically
    Posted to The Workbench (Forum) by manfy on Thu, May 20 2021
  • Re: CD 5500 repeat plays?

    The manual doesn't say anything about a repeat function, so... Generic Philips design? It doesn't look that way, but they're using the Philips CDM2 pickup on early models and switched to CDM4 later. If you have details on the data interface you can happily hack away. There's probably not much point in trying to get to the firmware in the uControllers. They're usually copy-protected. Or maybe not! It was the mid 80's after all. You can try to read the MAB8461 (5IC4). That should
    Posted to The Workbench (Forum) by manfy on Wed, May 19 2021
  • Re: copy duplicate Eprom STB-C

    Before you spend the time and effort in trying to find the chip with the right specs (which might not be as easy as you may think), it's better to confirm whether your programmer supports the chip and you have the drivers and the PLCC32 adapter available! Just read out the chip multiple times and see whether the result is consistent and the data makes sense. (I've had some bad experience with programmers that - in theory - were capable of handling certain EPROM's but in the end they just
    Posted to The Workbench (Forum) by manfy on Fri, May 14 2021
  • Re: Beogram CD 5500 open and then close?

    [quote user="Peter8300"] ... There's the adjustment screw next to the drive wheel (or whatever it's called) which kinda fell apart when I opened up the machine. ... [/quote] Could you be a bit more specific? With "adjustment screw", do you mean that white eccentric plastic gear you're pointing at with the torx screw driver?? If so, I don't really see that in the service manual -- and the manual doesn't say anything whatsoever about any adjustment. The part
    Posted to The Workbench (Forum) by manfy on Wed, May 5 2021
  • Re: Beogram CD 5500 open and then close?

    Thanks! I missed that one in the description. That clears things up. The function of the rubber is now obvious. It is supposed to dampen the "bumping sound" when the tray hits it and at the same time the friction holds the tray in place. I would just use a normal flat rubber band that you can find in stationary shops or everyday supermarkets. I just googled "flat rubber band" and checked the images -- they offer thousands of variants. Cut that to size, use Pattex (which is an
    Posted to The Workbench (Forum) by manfy on Wed, May 5 2021
  • Re: Beolab 4500 (mondriaan?)

    [quote user="bwest1000"] also, btw - I noticed a very small dent in the stainless steel. i dont suppose there is any way to repair that? i am really into buying these old beo products. i's like collecting old works of art. [/quote] Hmm, now that sounds trickier. Is it a sharp dent? If so, you may be out of luck. Looking at the pictures from Leslie's post < here >, I'd say there's no way to access the rear side of the panel without destroying it. And to fix a sharp
    Posted to The Workbench (Forum) by manfy on Sun, Apr 25 2021
  • Re: Beolab 4500 (mondriaan?)

    [quote user="bwest1000"] nevermind - found it. i don't really solder or know what to do. i am not sure i should attempt this. [/quote] It looks like a very simple job, but if you don't have any experience it probably also means that you don't have the right tools available. Good tools and all "the little bits and pieces" can cost you easily $50++ Just bring it to any electronics repair shop and give them a printout of the service manual. They will have it done in half
    Posted to The Workbench (Forum) by manfy on Sat, Apr 24 2021
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