BM5500 real time clock not running with power off

4 replies
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Offline
beonix (archived2)
Bronze
Posted June 15, 2018 at 21:54 GMT
#2253823

Hi All...  this is my first posting, so apologies if I don't get it right...

 

I have a BM5500 that would not bring on the STANDBY LED at power on... It turned out that the lithium 3v battery had expired, exuding fumes that had corroded the EPROM legs/socket...

 

I have replaced the battery and cleaned up the EPROM/socket, and the unit powers up normally...

 

However, if I set  the CLOCK with the MCP5500, it starts running, and keeps time whilst the amp is powered, even in STANDBY... But if the mains power is removed, it forgets the time (and other parameters such as VOLUME, BASS etc)...

 

It is odd, as the real time clock chip is clearly running... the symptoms would seem to indicate that the battery is again dead (possibly answering my own question here)...

 

Has anyone experienced a similar problem??

 

Tony

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beonix (archived2)
Bronze
Posted June 15, 2018 at 22:45 GMT
#2253824

I am being a bit stupid here... just checked out PCD8751, and it is just a small EEPROM, and has no real time clock, so little wonder that the CLOCK has to be set every time the 5500 is powered up on mains...

 

This still leaves me the problem that adjusting the VOLUME and pressing SET, does not store the new VOLUME setting into the EEPROM, as the next time the 5500 is powered up, the VOLUME returns to 44...

Tony

DI
Offline
Dillen
BronzeModeratorFounder
Posted June 16, 2018 at 00:03 GMT
#2253825

Check the 13V and 8V supplies, they needs to be correct and clean (note that the 13V supply is wrongly stated as -13V in the manual) ,
- and check the voltages to the processor module.
Replace the four small capacitors in the voltage regulator area.

Martin

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beonix (archived2)
Bronze
Posted June 22, 2018 at 14:10 GMT
#2253826

Thanks Martin for your suggestions... 

 

The storage at power down was my own fault... The battery works better when it is the right way round...

I have replaced the four small caps in the power supply as you recommended and currently all is well...

 

I will soak test for a few days to make sure it is stable...

 

Tony

 

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