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
My Beomaster 8000 stopped turning on out of stand-by mode. Got the red stand-by display segment, but the unit has no response from keypad or remote. I checked the fuses and mains supply output, they all look fine. I checked voltage at C35 and see 8.2vdc. This was still the original cap so I replaced it with a new 10uf cap. The old one measured 15.2uf. One strange behavior is that from stand-by, when I unplug the mains, i can hear the relays cycle. I put my DVM on the stand-by switch line that should toggle between 0-5vdc at R50 on board 6 and saw a 12vdc spike when I disconnected the mains power and heard the relays cycle. Is there an existing thread that has a good troubleshooting/repair to address this issue? Thanks
Beomaster 8000 generally;
- Bad capacitors- Cracked solder joints at connectors- Bad connectors- Bad processor board vias- Any combination of the above
Start at the 5V supply to the processor. Is it properly filtered?
Martin
Measured almost 8vdc output at 6IC4. Input voltage was in spec at 10.5vdc. I replaced the MC7805 voltage regulator and it’s back up and running. I have read a few comments about the heat generated in this area, the heat sink tucks up inside the housing. Is there a quality difference in voltage regulators such that one would run a bit cooler?
Thanks
Roger
captroger: Is there a quality difference in voltage regulators such that one would run a bit cooler?
Is there a quality difference in voltage regulators such that one would run a bit cooler?
There are no shortcuts in Ohms law.The regulator drops a certain amount of voltage at a certain amount of current.No matter how you do it , be that a resistor or a voltage regulator etc. - the amount of power generated will be the same.A larger cooling fin would bring the temperature down but the total power dissipated would be the same.