ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Along with a battered Master Control Panel 5000, which presented an interesting repair challenge, (in another thread) I have half a stack of Beomaster 5000 system, namely a still functioning CD50 with a bad eject belt and a "Brain Dead" Beomaster 5000.
The Beomaster lights up the LED display when plugged in, usually displaying a number 28. Controls and the MCP are unresponsive, indicating CPU trouble. Also, the main relay remained silent.
Taking a look inside revealed a few exploded electrolytic capacitors and very high ESR on many capacitors, especially on the power and audio amp board 2. Uh oh... did the unobtainable processor chips survive? So. I go through and replace the exploded caps and ones relating to power. Also, I replaced the main relay, as the contacts looked pretty awful and I had a spare new one left over from the Beocenter 7000 project. Plug it in and... no change.
Pull out the processor board and C68 is exploded. Replaced, with no effect. Pry open the shielding can to find a 3V coin battery soldered in that surprise! still puts out 3 volts after 35 years. A look at the schematic shows the processor has two reset pins, each with an affiliated electrolytic cap, C59 and C65, which both have high ESR in circuit. Pull them out and Ah-Hah! infinite ESR and a couple of PF on one and the other is open.
Solder in replacements for C59 and 65, re-assemble, plug in.. and a "Click" as the main relay pulls in for standby, lighting the standby LED! Press the panel switches and the Beomaster wakes right up like it should.
Next, to see if the CD50 will talk to this thing. So, next step is to fabricate a half-meter DIN7 cable and... surprise! the Beomaster communicates with the CD50 just like is should.
Success! As the Beomaster is now functional, I can order the remaining several dozen capacitors, the belt for the CD50 and see how this thing "stacks up" against the Beocenter 7700. Perhaps a matching Beocord and Beogram will present themselves....
¡No entiendo Español!
NEIN! Nicht Versteh!
Я немного говорю по-русскии но не очень хорошо... и
I'm not very good at English either! Maybe someday I'll find a language I'm good at?
I am so glad I found this post from Keri. I also have an old Beomaster 5000 that had given up the ghost. It sometimes would work from the MCP, but never from the control panel. I checked the ribbon and all paths were fine. Recapped the amp and power board, same issue.
When I finally found this post and replaced C59 and C65 on the control board it has come back to life.
Now I can recap the rest of it and have some confidence I'll have a working receiver when it is all over.
Thanks Keri!
Jeff