davros
Active Member
So I have put off restoring my SX-850 while I "sharpen" my skills. With the exception of some minor circuit board repairs I have made little progress. Tube amps is the limit of my proficiency so far, but I'm going to go in head first and start this project anyway.
Feel free to pipe in and throw out advice, it is both welcome and I am looking for it!
My plan is to begin with a thorough cleaning and Deoxit job and verify current operation. It works now but it is scratchy at best. I am then going to begin with a recap, and replacement of known faulty transistors. I have a pretty complete BOM that I will be posting below. I have all of the items on hand at the start of the project.
My first restoration step will be to replace the Capacitors in the power supply (Board AWR101)
Then test operation
Second step is to replace the known "Bad Actor" Transistors
Then test operation
I will repeat this with the following boards in the following order...
Equalizer Amp Board (AWF-011)
Flat Amp Board (AWG-038)
Tone Amp Board (AWG-039)
Protection Board (AWM-062)
Filter Cap Replacement
Switch Assembly Board (AWS-094)
Power Amp Board (AWH-059)
The power Amp board looks to be the toughest one and the end of the chain, so to speak. Following that I will adjust DC offsets and Idle currents.
Feel free to pipe in and throw out advice, it is both welcome and I am looking for it!
My plan is to begin with a thorough cleaning and Deoxit job and verify current operation. It works now but it is scratchy at best. I am then going to begin with a recap, and replacement of known faulty transistors. I have a pretty complete BOM that I will be posting below. I have all of the items on hand at the start of the project.
My first restoration step will be to replace the Capacitors in the power supply (Board AWR101)
Then test operation
Second step is to replace the known "Bad Actor" Transistors
Then test operation
I will repeat this with the following boards in the following order...
Equalizer Amp Board (AWF-011)
Flat Amp Board (AWG-038)
Tone Amp Board (AWG-039)
Protection Board (AWM-062)
Filter Cap Replacement
Switch Assembly Board (AWS-094)
Power Amp Board (AWH-059)
The power Amp board looks to be the toughest one and the end of the chain, so to speak. Following that I will adjust DC offsets and Idle currents.
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