SG-9500 Restoration

I am about half way done restoring an SG-9500 that I picked up two weeks ago along with two full racks of gear (here).

So far I have:

Stripped and cleaned the chassis
Cleaned the face plate with Mother's Chrome Polish
Replaced the power supply caps with Panasonic FC
Replaced the regulators with new 2SD313/2SB507
Replaced the other transistors with low noise Zetex 694B and 795A
Replaced the lytic caps in the EQ with Elna Silmic II
Replaced the mylar caps with Polypropylene caps (Panasonic ECQ-P(Z) and WIMA)
Replaced all fuses with new 500mA LittleFuse
Reflowed all the solder joints.

Right now I have one channel done as you can see in the pics - I am thinking about A/Bing the unit to see if I can tell a pronounced difference.

I know this is overkill... but once I get started I have a hard time pulling the plug!

Also torn down to be restored next is a TX-9500II, SPEC-1, SPEC-4, SG-303, and RG-2. I restored the DT-500 this weekend. Then they will all get shoved back in to a rack!

I wish I could find modern opamp replacements - I had great results a few months ago replacing all the opamps in a Sansui SE-7 with Burr Brown OPA2134's...

I did the deoxit treatment to the sliders and switches later last night. I will put the unit back together tonight if I can find time and post the results.

Put it all back together and went to use it - sounded horrible! Tore it down again - started testing levels at the power supply - wouldn't you know the replacement 2SB07 I got from MCM Electronics is a dud. I was getting only milivolts where I should have been getting about ~15VDC.

Put the old 2SB507 back in, works like a champ!

Lesson learned: Test transistors from MCM electronics before using them! I have used them from this same batch without issue three times while restoring Pioneer SA-9100 Power Supply B boards. I still have two of them - I will go back in and check - this makes me nervous that they make be fakes.

Back in business - I think it sounds wonderful. Probably not a good return on investment sound-wise but this hobby keeps me out of trouble.

(update) I tested the other 2SB507s in the bag from MCM and they test the same on the diode test - I need to get a full fledged transistor tester. Time to check eBay.

Did you A/B the channels? Any difference?
I have 2 - SX-1010's; one stock the other almost fully recapped (stock PS caps). I played with running one to each channel (in mono) simultaneously. The recapped sounded noticeably clearer.
JimB

I don't have an distortion analyzer so I cannot confirm it quantitatively but my mind thought the recapped channel sounded more "clean". I was pumping music in mono from my PC to the EQ, then to a Nakamichi PA-7II and finally Thiel CS3.5's.

I stood on the other side of the room because I had to use the computer balance control to swing from left to right.

I would say it does indeed sound "better" to my ears. I don't know that I would say the increase in sound quality was worth the cost in parts (those little poly caps are expensive!) but the peace of mind knowing I won't have to go inside for another 20 years was worth it.

I have an RG-2 on the bench right now for the same kind of restoration. I am interested in this one - never used it - has the typical broken push button switch issue but I am waiting on a replacement from eBay. Will post pics of that in a different thread when complete.