JoseHH
Well-Known Member
I always wanted to have a Sansui AU-919, now I am in Bangkok and here found one AU-D907 for about 275 USD. The seller imports second hand audio equipment form Japan. Before I payed for it, I listened to it and asked the seller to remove the top cover. Although i spotted that the L-CH output transistors were the expected NMA/NMC1012, i saw that the right channel had transistors whose lettering indicated a different batch. I knew that there has been a previouds repair on the unit. I saw the s called "Black flag" capacitors in the driver board. The volume potentiometer is ALPS but it does not have the incremental "clicks" upon rotation. The amplifier powered up ad come out of protection, and sounded ok at low volume. I tested the front panel functionalities that i could and they seemed to work fine. Considering that the amplifier worked, and that its cosmetic appearance was acceptable and that i wanted to have this model, i decided to buy it even if the price is a bit to high. Now I am at home and i took a closer look at the amplifier and i was shocked to see the previous repairs. When i loosen ed the driver board with the heat sin to have a better look at the output devices i saw that the transistors replacements were incorrect. I am surprised the unit works at all!. Expecting to receive guidance from the experts in this forum, I decided to open this thread because i did not see many threads on the Japanese version of the AU-919. I think it will be a nice challenge to get this unit some preventive care to get it working safely. I have read all i could about the AU-919 and i have printed the service manual and an enlarged copy of the schematic. Now I am up for some fun removing the bad components.
The transistor with the tape is PNP type 2SA-747A !!!!, and is supposedly complementary is a 2SA1116, while it should have been 2SC1116. Please tell me if I am wrong but i think that these two transistors are either not connected, open or just by pure luck dont do anything. The Fuse F-02 blew (probably at the time the right channel failed) and it was bridged with a wire. Also, the driver transistor 2sd-382 has been replaced by a 2sd-525. I will replace all the black flags and try to get a better set of driver and output transistors.
The question is, should I get the expensive set of TO-3 2sa1116/2sc2607 from vintage sansui or should i go with the TO3-P modification suggested by Ilimzm and Echowars?. I have a set of the 2sa1294/3263 and enough MJ21195/6 to put on the unit. I will appreciate it having some input from other members of this forum.
Thank you.
The transistor with the tape is PNP type 2SA-747A !!!!, and is supposedly complementary is a 2SA1116, while it should have been 2SC1116. Please tell me if I am wrong but i think that these two transistors are either not connected, open or just by pure luck dont do anything. The Fuse F-02 blew (probably at the time the right channel failed) and it was bridged with a wire. Also, the driver transistor 2sd-382 has been replaced by a 2sd-525. I will replace all the black flags and try to get a better set of driver and output transistors.
The question is, should I get the expensive set of TO-3 2sa1116/2sc2607 from vintage sansui or should i go with the TO3-P modification suggested by Ilimzm and Echowars?. I have a set of the 2sa1294/3263 and enough MJ21195/6 to put on the unit. I will appreciate it having some input from other members of this forum.
Thank you.