promitheas73
New Member
Hello everyone
I own an old Marantz PM710 DC and the power transistors of one channel are off. The transistors are the following:
2SC2588A & 2SA1108A.
These are very difficult to find as you already know, but after a lot of search i found an AliExpress supplier who seemed to sell original NOS NEC transistors. So the obvious question, are these original of fake?? Anyone who has the experience (especially for the specific transistrors) may help.
What i 've done so far:
1. Drop voltage between B/C, B/E seems ok for all of the transistors (0,510 ~ 0.530 V)
2. hFE varies from 80 to 210 (don't know what is that number exactly but compared to my original working pair seems ok cause i get hFE of 50 for the old original pair)
3. Checked NEC logo vs my old pair doesn't seem the same. Also the color and the texture of the plastic case doesn't seem the same.
4. The outer case of the old ones is much shiner (better polished) than the questioned ones.
5. The batch code number (the last line on the trans itself) is the same for all the 2SC2588A's & the same for all the 2SA1108A's. Is this supposed to be the case?? My original old pairs have different batch code numbers so i think this is a very strong evidence that these are fake trans (correct me if i am wrong).
Pls consider that i am not an electronics expert. I ve made all my measurements with a multimeter which is the only electronic gear i have.
Thanks to all in advance & pls check my photos.
I own an old Marantz PM710 DC and the power transistors of one channel are off. The transistors are the following:
2SC2588A & 2SA1108A.
These are very difficult to find as you already know, but after a lot of search i found an AliExpress supplier who seemed to sell original NOS NEC transistors. So the obvious question, are these original of fake?? Anyone who has the experience (especially for the specific transistrors) may help.
What i 've done so far:
1. Drop voltage between B/C, B/E seems ok for all of the transistors (0,510 ~ 0.530 V)
2. hFE varies from 80 to 210 (don't know what is that number exactly but compared to my original working pair seems ok cause i get hFE of 50 for the old original pair)
3. Checked NEC logo vs my old pair doesn't seem the same. Also the color and the texture of the plastic case doesn't seem the same.
4. The outer case of the old ones is much shiner (better polished) than the questioned ones.
5. The batch code number (the last line on the trans itself) is the same for all the 2SC2588A's & the same for all the 2SA1108A's. Is this supposed to be the case?? My original old pairs have different batch code numbers so i think this is a very strong evidence that these are fake trans (correct me if i am wrong).
Pls consider that i am not an electronics expert. I ve made all my measurements with a multimeter which is the only electronic gear i have.
Thanks to all in advance & pls check my photos.
