AK friends, today I put about four hours into the remaining fixes for the Sansui 210. Everything is working dynamite and so this post is to document the "cookbook" that I used to revitalize the Sansui 210. I want to especially thank
@two.dogs @dlucy @kevzep @stereofun and everyone else who replied for their contributions to this final working receiver product.
In this project, the preamp, amp, and power supply sections were freshened up as follows:
Power Supply, replaced stock 1000uf cap with 1500uf cap. So far no negative affects from this. Just wanted to give the amp a little more reservoir to pull current from. The stock 1000uf cap just seemed a little under size to me.
Amp and preamp, recapped with mostly nichicon KL. I ran low on 100uf caps and used a new Sprague cap in a pinch. I did not have replacements on hand today for C004 and C807. Those are the only remaining stock electrolytic caps. I did also place a .1uf metalized polypropylene cap in parallel with the new 1000uf Nichicon KL coupling caps. I did not replace any ceramic caps. All diodes are original. One bad resistor was located and replaced with the same value.
Transistor replacements as follows:
2SC693 = KSC1845FTA
2SC1312 = KSC1845FTA
2SC1364 = KSC1815YTA
2SA678 = KSA1013
2SD315 = KSD1408Y (outputs)
Output Transistor replacement:
Outputs were replaced with KSD1408Y. This transistor is TO-220 and does not have a collector connection on the case of the transistor. Therefore all 3 wires for base/collector/emitter were soldered to the transistor. Shrink wrap was used to further insulate each output transistor connection as they do thread through the opening in the heat sink which can easily cause short if a contact gets bent or bumped. Diodes on the heat sink were simply moved and used stock clips to attach them next to the transistors.
Here is the (mostly) recapped amp and preamp board:
Some additional notes and lessons learned with this project:
1. The receiver (at least MINE) is susceptible to RF interference. Cell phones placed near the receiver can cause static sound from the speakers, especially if there is an active call on the phone or certain apps are running on the phone.
2. Check the solder joints at the edges of the amp board where it is soldered to chassis ground. Like another AK member I found one of these joints had cracked and was a loose connection.
3. The receiver sounds very nice once recapped and with the transistor replacements. I will get a lot of enjoyment out of it and to me was worth the time. It drives my Polk Monitor 5 Series 2 speakers well. I don't tend to listen to super loud music so this receiver may not be the best choice for some people who need more guts. But for me in my small office paired with these efficient speakers, it sounds very nice. Specifically, I want to call out that the midrange initially had a harshness to it and was a bit fatiguing. This did not go away until after the recap. Just replacing transistors did not solve this but the recap did.
4. Look closely here at the tracing near one of the 1000uf coupling caps. It has been scratched out by the factory. I wanted to document that here. I almost "repaired" this before realizing it would cause a catastrophic short of the coupling capacitor. You can see it here below the point to point wire:
Again, thank you to everyone who helped contribute. Hopefully this thread will be of use to other Sansui 210 owners.
