Beomaster 5500 source selection

7 replies
MA
Madskp
Gold
1759 posts
Posted June 8, 2023 at 06:50 GMT
#687692
My BM5500 has developed a fault when choosing sources. If I select CD, TAPE or phono it will flicker between sources in the display and a relay is clicking continuesly. If I select radio this doesn't happen The last thing it was used for was in a test scenario with a Beolink converter connected to the TAPE2/AUX input if this can give any hint as to what could be the reason for this behaviour. Any ideas where to start looking? Thanks in advance

Location: Denmark

DI
Die_Bogener
Bronze
1477 posts
Posted June 9, 2023 at 08:38 GMT
#702113
There is a LED driver chip MM5450 on the display board. If there is a problem with overload of a segment... the chip has internal led driver resistors... it will have problems to activate the defekt segment causing a power failure of the display/cpu... that's the flicker. Try the amp without speakers to activate from 0 to 64 to check all these segments. Usually there will be a "8" problem... and a problem with the source led. It can be the chip or the power supply itself. Replacing the chip is very skilled work and the chip is hard to get. Usually some caps in the power supply are the cause...
MA
Madskp
Gold
1759 posts
Posted June 9, 2023 at 11:08 GMT
#702118

Location: Denmark

DI
Die_Bogener
Bronze
1477 posts
Posted June 9, 2023 at 11:49 GMT ? Edited June 9, 2023 at 11:49 GMT
7-segment and Led's for the source are done with the same chip... and the relais.
MA
Madskp
Gold
1759 posts
Posted June 9, 2023 at 15:26 GMT
#702123
Ok thank you, then I will take a look around there when I ger it open

Location: Denmark

MA
Madskp
Gold
1759 posts
Posted June 10, 2023 at 10:57 GMT
#702132
Had some time look further into it today.
About the relay clicking, now that I have the BM5500 open I can see that it is the relay behind the plug PCB that is clicking rapidly But I noticed that the relay on the PSU board (betwen the transformer and the large caps) is also clicking once in awhile if that is an indicator for something.

Location: Denmark

MA
Madskp
Gold
1759 posts
Posted June 14, 2023 at 19:03 GMT

Location: Denmark

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