Project Update - Removal, Repair, & Reinstall Strategy
Understanding that repairing and reinstalling one board/section at a time is preferable, I'm hesitant to implement this approach due to the level of tear-down required to access each section (i.e. e.cap board, main PSU board, main amp board, etc) along with the need to reconnect and disconnect cabling multiple times. Removal of the E.Cap board required disconnecting main amplifier leads along with other leads from the main PSU board, and the removal of these boards has also provided much greater access to the removal of the main amplifier boards. Moving forward with the standard strategy of repairing and testing each section individually would require that I complete both the E.Cap and Main PSU board, reinstall, and reconnect all cabling, including those from the Main Amp Boards in order to properly test those repairs. Once testing has been completed, all Main Amp Board cabling would then need to be disconnected again in order to remove and repair them. While this may be an option, I believe any gains accrued in the ease of troubleshooting would be far outweighed by the negatives/risk associated with connecting and disconnecting wires multiple times, therefore, I decided to remove the Main Amplifier Boards wile the E.Cap and Main PSU Control Board have been disconnected. I believe the destruction of the right speaker terminal on the main PSU board validates these thoughts; while proceeding no differently than the removal of the left speaker lead, with great caution, and an iron set to 600*, the right terminal simply broke in half when heated! (see pic below).
Current Disassembly & Board Status
1.
E-Cap Board - Removed / All electrolytic and ceramic capacitors have been removed waiting for the installation of new components
2.
Main PSU Control Board - Disconnected from E. Cap board but still connected and wire-wrapped to the receiver - waiting for testing of old components and new components installation. Will modify location of TR712/715 according to Post #119.
3.
Main Amplifier Boards - Disconnected and removed from the chassis. Boards are extremely dusty and dirty. Boards need to be removed from heat sinks and components tested to determine status of transistors. Would appreciate some experienced advice on testing along with information concerning any "known bad" transistors or other components that should be replaced. (see pics below)
Main Amp Board 1 Condition (Main Amp board #2 is in the identical condition)
Interstitial Space between heatsink & TR613/614 below
TR606 Below
TR611/612 Below
TR608 Below
Go Forward Strategy - Accepting All Advice
Since the Main Amplifier boards and heat-sinks have been removed, access to the pre-amp and tone boards has been greatly improved (see pic below). Its unclear to me whether I should move forward with working on repairs to the pre-amp and tone boards next due to the improvement of access and would like to gain some advice here. It seems logical to work on the pre-amp/tone boards next since access has been improved but I'm unsure at the moment. The following sequence would appear to be the most logical:
1. Repair Pre-Amp/Tone Boards
2. Repair Main Amp boards and reinstall
3. Reinstall Transformer
4. Repair E.Cap Board and reinstall
5. Repair Main PSU Control Board and reinstall
6. Repair lights
Please post all advice and comments freely. Do not hesitate to share any errors you see along with technical information for component testing or known bad components relative to any board.
And finally, here's wishing everyone a happy and healthy New Year! And for all those traveling and partying this evening, PLEASE BE SAFE!