Sansui 2000a muting issue

[johnhoef]

Hello, everyone,
I hope I can get some help here concerning a non working muting function on a Sansui 2000a. Looking at the schematic, I see the 2000a schematic does not reflect how my unit is designed. The 2000x schematic is closer, but even that is not exact, but I'll use this schematic. Since the tuning meter is working normally, we can assume TR201, and T205 is in working order. The secondary coil of T205 drives the tuning meter circuitry. Then, the signal is tapped off the secondary through c222, and drives the muting circuit. This muting circuit consists of a couple diodes, TR202, and TR203. I replaced C232, and TR202 with KSC1815. I checked R219, R232, and R233...they are all good. Diodes 204 and 205 are germanium diodes, and check good. Grounding the base of Q202 engages mute, so this tells be the problem lies in the post T205 and pre TR202 area. Not much circuitry involved here, and yet, I am having difficulty getting muting to work! I haven't checked or replaced C222, C228, or C229. These are ceramic capacitors which rarely fail, but I suppose I should replace them next. Any thoughts?

 

[correiadesa]

Hello, everyone,
I hope I can get some help here concerning a non working muting function on a Sansui 2000a. Looking at the schematic, I see the 2000a schematic does not reflect how my unit is designed. The 2000x schematic is closer, but even that is not exact, but I'll use this schematic. Since the tuning meter is working normally, we can assume TR201, and T205 is in working order. The secondary coil of T205 drives the tuning meter circuitry. Then, the signal is tapped off the secondary through c222, and drives the muting circuit. This muting circuit consists of a couple diodes, TR202, and TR203. I replaced C232, and TR202 with KSC1815. I checked R219, R232, and R233...they are all good. Diodes 204 and 205 are germanium diodes, and check good. Grounding the base of Q202 engages mute, so this tells be the problem lies in the post T205 and pre TR202 area. Not much circuitry involved here, and yet, I am having difficulty getting muting to work! I haven't checked or replaced C222, C228, or C229. These are ceramic capacitors which rarely fail, but I suppose I should replace them next. Any thoughts?

I have the exactly same issue on my recently repaired 2000a: everything works after recap except muting and mpx noise canceler. Did you find out what was the issue with yours?