There is a 954 DAC which when changing frequency (only from high to low) gave a sharp squeal and chirp at the output. Martin Reynolds gave advice on the subject and on his suggestion we replaced the capacitors in the low-current parts.
An expert engineer did the replacement. We checked all parts and soldering but the DAC does not start. It takes power, there is a relay sound when it is turned on, a couple of LEDs on the motherboard flash but the display is completely dark and the DAC function does not work. We checked all possible connectors that could oxidize. The outputs of the power supply are present and very accurate.
All the LEDs of the display flashed once and stayed that way, but the next time it was turned on, it was already dark and did not happen again.
Our equipment is quite good, we are an expert IT service, if there is an EPROM problem we can handle it with your support.
Please help us if you have an idea.
I think the software version is still factory, as I remember, v1.12
Serial number 954-6b2-5b3-2c1-2b1-03248