So I met a nice couple who are in the appliance repair business when they came to evaluate an issue we were having with our oven (Urgent Care Appliance Repair). Somehow Trevor noticed the SX-750 and the SX-850 I have in my office and told me that he had a SX-650 that had belonged to his dad and was being used by his son. He said it all works and he would very much like to restore it for his dad. I have been looking for another project unit without much luck and he was more than willing to work out a trade for the oven work. Off we go… Before i started the disassembly of this unit I first brought it up using a DBT and then tested the functions with speakers attached. All seem to work.
The vinyl veneer on this unit is really bad and I plan to address that at a later stage. For now I just wanted to get the knobs and face plate off so that I could start cleaning out the 40+ years of nastiness.
I will say that the smaller chassis receivers of this era are a bit more difficult to disassemble. You have to be VERY careful when removing the black cover over the pots and switches as it would be very easy to damage the tuner string. The amount of dust and nasty in this unit was significant and I spent 2 days with compressed air and lot of alcohol and swabs.
The post on the function selector (right most knob) was broken so I went on the hunt and found one on Ebay for a reasonable amount. The unit also needs a foot and the Ebay seller was kind enough to throw one into the deal. Getting this unit disassembled to a point where I could get this switch out was a challenge, but it went smoothly overall.
While I had the function selector switch out it seemed like a good time to Deoxit the knobs and switches.
In this picture you can see that the new switch as been soldered in place and the major dust and grime has been removed.
This is the tone board AWG-049 before cleaning, Deoxing of the pots and switches and replacement of the electrolytic capacitors.
Here is the cleaned board with the new Nichicon UFG capacitors installed. I think the next bit of work will involve replacing the main capacitors.