In April, I posted about picking up an SX-750 that I'd planned to refurb and give to my son as a college grad present. Well, after getting sidetracked with house projects in preparation for the graduation party, my timeline slipped and I'm just now completing the project. I know I like to read about such projects so I thought I'd follow up. (previous thread http://www.audiokarma.org/forums/showthread.php?t=653119)
The unit was in decent shape, faceplate/knobs were dirty, but fairly clean, however the vinyl woodgrain was a mess, peeling/missing portions. I ended up veneering the case w/paper backed walnut veneer and used General Finishes satin Oil and Poly finish (no stain - 4 coats wiped on w/a t-shirt). I'd read about the finish on a homebuilt speaker forum and was very pleased with the product. Easy to apply and excellent results without looking like it was coated in plastic. Next, I did a complete re-lamp with parts sourced from our friend djwojo.
My order from Mouser arrived weeks ago, but I failed to check it against the BOM requirements. I went to begin the re-cap last week and realized all the 100mf caps had failed to make my order (my fault NOT Mousers!).
I had planned to work one board at a time, test on the DBT, then full power, then move on to the next board. Since the missing parts impacted virtually every board except the power supply (1 cap and a bunch of diodes that I had), and wanting to maximize the return on my extended holiday weekend here, I defied logic and convention and replaced all caps on all boards at once. I saved the DBT testing for last and I was extremely fortunate in that there were zero faults! I was sweating it, I can tell you. I would NOT recommend this approach. Just too many parts to have not screwed something up, but I did go back and verify continuity in areas where a pad lifted, also polarity/values, etc.
I set the idle current and finally hooked up to speakers, a turntable, antenna and iPod dock. All modes worked and she sounded great! The unit functioned and sounded good before the re-cap, but it showed signs of pretty heavy use so it provides some piece of mind. Also, though I ordered all the transistors, I only replaced the diodes on the power supply (-099?) board so far. I will likely listen to it for a few weeks and then go back in.
I'll try to attach a few pics now and check back later w/some pitfalls/caveats for others that I ran into. Can't leave though, without saying a big 'thank you!' to MarktheFixer, Watthour, BobHelms and others who have shared their wisdom and experience with me directly and through other helpful threads. What a great community here! = )
The unit was in decent shape, faceplate/knobs were dirty, but fairly clean, however the vinyl woodgrain was a mess, peeling/missing portions. I ended up veneering the case w/paper backed walnut veneer and used General Finishes satin Oil and Poly finish (no stain - 4 coats wiped on w/a t-shirt). I'd read about the finish on a homebuilt speaker forum and was very pleased with the product. Easy to apply and excellent results without looking like it was coated in plastic. Next, I did a complete re-lamp with parts sourced from our friend djwojo.
My order from Mouser arrived weeks ago, but I failed to check it against the BOM requirements. I went to begin the re-cap last week and realized all the 100mf caps had failed to make my order (my fault NOT Mousers!).
I had planned to work one board at a time, test on the DBT, then full power, then move on to the next board. Since the missing parts impacted virtually every board except the power supply (1 cap and a bunch of diodes that I had), and wanting to maximize the return on my extended holiday weekend here, I defied logic and convention and replaced all caps on all boards at once. I saved the DBT testing for last and I was extremely fortunate in that there were zero faults! I was sweating it, I can tell you. I would NOT recommend this approach. Just too many parts to have not screwed something up, but I did go back and verify continuity in areas where a pad lifted, also polarity/values, etc.
I set the idle current and finally hooked up to speakers, a turntable, antenna and iPod dock. All modes worked and she sounded great! The unit functioned and sounded good before the re-cap, but it showed signs of pretty heavy use so it provides some piece of mind. Also, though I ordered all the transistors, I only replaced the diodes on the power supply (-099?) board so far. I will likely listen to it for a few weeks and then go back in.
I'll try to attach a few pics now and check back later w/some pitfalls/caveats for others that I ran into. Can't leave though, without saying a big 'thank you!' to MarktheFixer, Watthour, BobHelms and others who have shared their wisdom and experience with me directly and through other helpful threads. What a great community here! = )