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
I made the mistake of unplugging my BM5500 to dust behind it a while ago, and it hasn't quite been the same since. When I reconnected it, the sound settings had gone nuts (bass and treble turned way down, balance all the way over to one side), and my tuner presets were gone, replaced by all sorts of random ones.
I understand that such things can happen if the backup battery gets low, but as well as all that, the tuner is behaving very strangely. For example, if I type GOTO-8-9-3 on my MCP to tune 89.3 FM, the MCP display will show 89.5 FM, and the audio will be from a station that I know is at 91.1 FM. Other stations seem to be similarly offset. Tuning manually using << and >> results in the same thing – the displayed frequency is 'offset' from the actual frequency by ~1.6 MHz.
I have tried leaving the unit unplugged for a few days, and run the CPU and RAM tests as per the service manual, and everything checks out fine. Since there seems to be some kind of dislocation between the actual frequency and the one that the tuner is reporting, I haven't tried the FM tuning test.
This problem is really getting at me, and I'd appreciate some wisdom about further things to look into.
My first impression with such strange behaviour is, that the BM5500 needs a good overhaul. Some 10uF capacitors in the tuner section needs to be replaced. But byside that there are more located in the powersupply section, which needs to be replaced.
Such behaviour can happen just from one to another day...
Good to know. It seems that executing the RAM test leaves it in an operating state until the power is disconnected again, so I at least have a way of making it work (although getting to the test-point and reassembling it inside my stereo cabinet is not a feat that I want to repeat).
As far as replacing caps goes, are there any other trouble spots that I should attack while I redo the ones mentioned?