Have yourself a merry Christmas. I wish you a wonderful time with your beloved.
Good news for me is that the new power supply is basically working… more or less. First, I was too motivated to add another microcontroller unit (MCU) to measure the voltages and to trace other ongoing things. As a result, all those components drained too much current and the temperature control of the transformer shut off cut the power after about half an hour. Great to see that Philips implemented a temperature control. It cannot be seen as it is inside the transformer but it is visible in the circuit diagram of the service manual.
Anyway, I removed the MCU and other unnecessary parts to save some energy. I removed the transistors to switch four voltages for the CD player on and off, because they often failed, and replaced them with two relays I need a little bit more extra power. In fact 100mA for each relay. In the meantime I found other relays with 12.5mA which should do a better job.
Another good thing of rebuilding circuits is that I learned a lot, not only in electronics, but also why Philips implemented some weird circuits. Switching between different line inputs result in cracking sounds and therefore a circuit mutes the speaker. Well while that makes sense, it was new to me that Philips also switch to mute when the sound machine gets power off. Otherwise there will be loud cracking sound. I reimplemented parts of the mute circuit – except those when the machine gets powered by battery.
Let’s see how the Revision B will work…
