The Sony AV-3600 service manual was what I needed for the repair of this unit
Thanks for the good service
Dave
Text excerpt from page 38 (click to view)
CD TEST MODE
< How to Enter the Test Mode >
While pressing the SLEEP&OPEN/CLOSE key, insert the AC power cord to AC wall outlet. Pressing the [ ] key establishes the [Sled mode]. The [ ] display can be turned on and off by pressing the [ ] key . While the [ ] display is turned off: CLV-A Tracking servo: on Sled servo: on While the [ ] display is turned on: CLV-A Tracking servo: off Sled servo: off Pressing the [ ] key decreases the track number to -1. Pressing the [ ] key increases the track number to +1. Pressing OPEN/CLOSE key opens or closes the tray. The machine enters the [Sled mode].
< When the Machine Has Entered the Test Mode >
The system is initialized and the main power is turned on. During the test mode, the main power of the CD block is turned on always. The test mode starts with the [Sled mode].
< Types of Test Mode >
[Sled mode]
All displays of the FL tubes light. The optical pickup can be moved by pressing [ ] or [ ]key. Pressing the [ ] key establishes the [Play mode]. Pressing the [ ] key moves the sled to outer circumference. Pressing the [ ] key moves the sled to inner circumference. Pressing OPEN/CLOSE key opens or closes the tray.
< How to Exit the Test Mode >
Remove the AC power cord from power outlet, or turn off the system power.
[Play mode]
Lighting of all displays of the FL tubes are turned off and returns to normal display. The focus search (numbers of search is unlimited) is performed. When focus comes to in-focus, the focus servo is locked in and the machines enters the normal play mode. During [Play mode], GFS and sound skipping are not monitored. When focus becomes out-of-focus, another attempt is made to search for focus. The tracking servo and the sled servo can be turned on and off by pressing the [ ] key.
