Found a CD104 I'd tucked away in a cupboard many years ago and have been trying to get it running for the last few days, with limited success.
Initially, it couldn't find the TOC, but with the help of Mike Leach's servicing guide and the many posts on this forum and others, have made some progress...
Checked all of the PSU rails with a disk playing - everything is within a few hundred millivolts.
Fixed the 'griplet' connections between the double-sided boards by cleaning out the original solder (drilling through where needed) and soldering a through wire on each side, making sure of a good connection to the ground plane. There are 2 on the servo board and 11 on the decoder board. This allowed TOC to be found, but no audio, despite tracks being accessible via the controls, the disk spinning normally and the display doing what you'd expect
Greased the draw mechanism and cleaned and tested the 'draw closed switch'. A slight change - occasional audio for about 15 seconds - it's fine initially, but becomes more and more distorted and then stops.
Checked the mute signals (there are two), which seem correct. Tested the 'anti-bump' reed relays with a magnet - sound fine, but bypassed both channels with wire bridges to be sure. No change.
Re-soldered every connection on the decoder board and changed all of the 22uF coupling / decoupling caps. No result...
Running through the decoder board (checking against the service manual voltages) it seems the 16.8v expected on pin 10 of the DAC chips is high (17.5 and 18.3v). Does anyone know if that would be enough to cause a problem?
Throughout the process, once in a while, the 15 seconds of audio popped up randomly (in different location son the disk), which suggests the transport and chipset is basically functional, but something is interrupting either the data stream or audio signal somewhere in the circuit...
Thinking about changing the power supply caps and perhaps the 18v regulator, but if anyone has come across this problem and can suggest a solution, your advice would be much appreciated!
Initially, it couldn't find the TOC, but with the help of Mike Leach's servicing guide and the many posts on this forum and others, have made some progress...
Checked all of the PSU rails with a disk playing - everything is within a few hundred millivolts.
Fixed the 'griplet' connections between the double-sided boards by cleaning out the original solder (drilling through where needed) and soldering a through wire on each side, making sure of a good connection to the ground plane. There are 2 on the servo board and 11 on the decoder board. This allowed TOC to be found, but no audio, despite tracks being accessible via the controls, the disk spinning normally and the display doing what you'd expect
Greased the draw mechanism and cleaned and tested the 'draw closed switch'. A slight change - occasional audio for about 15 seconds - it's fine initially, but becomes more and more distorted and then stops.
Checked the mute signals (there are two), which seem correct. Tested the 'anti-bump' reed relays with a magnet - sound fine, but bypassed both channels with wire bridges to be sure. No change.
Re-soldered every connection on the decoder board and changed all of the 22uF coupling / decoupling caps. No result...
Running through the decoder board (checking against the service manual voltages) it seems the 16.8v expected on pin 10 of the DAC chips is high (17.5 and 18.3v). Does anyone know if that would be enough to cause a problem?
Throughout the process, once in a while, the 15 seconds of audio popped up randomly (in different location son the disk), which suggests the transport and chipset is basically functional, but something is interrupting either the data stream or audio signal somewhere in the circuit...
Thinking about changing the power supply caps and perhaps the 18v regulator, but if anyone has come across this problem and can suggest a solution, your advice would be much appreciated!