Beocenter 7700 “0” and “P” on the displays – no action

[Kuukeri]

Hi,

I brought home a BeoCenter 7700 which I thought would make a nice home music center to my living room as it is so beautiful. 🙂 Unfortunately there is a fault as none of the buttons work, and the display only says 0 an p on the different displays. I have googled and troubleshooted it a bit. I have tried to find out if the microprocessor is running. When checking the reset line, it’s at 2,5V, which is not correct? I have tried to swap out some of the electrolytic caps around the vcc line and reset line. The vcc on the chip is at 5v. Could someone point me to the right direction as what to check for next?

[Dillen]

Check for excess ripple on the supply voltages (bad filter capacitors).
If your CPU module has an electrolytic capacitor near the edge connectors, replace it.

Martin

[Kuukeri]

Hi, as I’m not proficient enough to test the ripple on the supply voltages, I got another power/amp board from a donor unit. 🙂 Swapping the board does not have any effect on the problem. I guess the new board could have the same problem, but it’s quite unlikely? I have also swapped all of the electrolytics on the pc board, but the problem still remains. The 2,5v on the reset line still bugs me. Is it correct? If not, what could be causing it?

 

Also the 6,5v supply is at 6.6v which should be ok.

Edit: I pulled the chip, and some of the chip legs are broken. I guess I’m going to have to find a replacement…

[Author]

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