Hello,
I'm trying to find some BJT's to fix a Technics integrated amp (SU-Z65), and I'm having a hard time. I live in Brazil, which makes it even harder - we have fewer stores here than you do in the US and Europe, and most of our stores have a very limited selection.
I'm not considering importing yet, because import taxes are huge here, and also because the customs have been increasing their inspections in the past 6~12 months, which makes some people wait for several months to get their goods.
The original transistors are 2SA1123, 2SC2631 and 2SC1685. After countless visits to several websites, I think I've got some candidates. Could you guys please take a look and see if I'm in the right track? This is what I've found so far:
* for 2SA1123:
- 2SA1016: I still don't have the confirmation if the store carries the 'K' version, for 120/150V. The 'regular' (non-K) version is for 100/120V, and the rails are at +/- 47V, so I'd rather get the 'K' version to have some extra room.
- 2N5401: This one is for 150/160V, but is not listed as a replacement, I just compared the datasheets. And it's relatively easy to find.
* for 2SC2631:
- 2SC2632: Also hard to find, but I'm waiting for a store's reply.
- 2N5551: Not listed as a replacement either, I just compared the datasheets. Relatively easy to find.
* for 2SC1685:
- 2SC945: Just found out that this one can be a replacement, will see if I can find it.
- 2N5551: Again, not listed as a replacement either, I just compared the datasheets.
When I say I compared the datasheets, I focused on breakdown voltages and hfe ranges. Is there anything else I should look at?
Thank you,
I'm trying to find some BJT's to fix a Technics integrated amp (SU-Z65), and I'm having a hard time. I live in Brazil, which makes it even harder - we have fewer stores here than you do in the US and Europe, and most of our stores have a very limited selection.
I'm not considering importing yet, because import taxes are huge here, and also because the customs have been increasing their inspections in the past 6~12 months, which makes some people wait for several months to get their goods.
The original transistors are 2SA1123, 2SC2631 and 2SC1685. After countless visits to several websites, I think I've got some candidates. Could you guys please take a look and see if I'm in the right track? This is what I've found so far:
* for 2SA1123:
- 2SA1016: I still don't have the confirmation if the store carries the 'K' version, for 120/150V. The 'regular' (non-K) version is for 100/120V, and the rails are at +/- 47V, so I'd rather get the 'K' version to have some extra room.
- 2N5401: This one is for 150/160V, but is not listed as a replacement, I just compared the datasheets. And it's relatively easy to find.
* for 2SC2631:
- 2SC2632: Also hard to find, but I'm waiting for a store's reply.
- 2N5551: Not listed as a replacement either, I just compared the datasheets. Relatively easy to find.
* for 2SC1685:
- 2SC945: Just found out that this one can be a replacement, will see if I can find it.
- 2N5551: Again, not listed as a replacement either, I just compared the datasheets.
When I say I compared the datasheets, I focused on breakdown voltages and hfe ranges. Is there anything else I should look at?
Thank you,
Vce0 max
Ic max continuous
P max
Cob @ relevant Vce, usually 10Vce or 30Vce.
Package style and pin out.
Ic max continuous
P max
Cob @ relevant Vce, usually 10Vce or 30Vce.
Package style and pin out.
Uh... would you care to elaborate on that? I couldn't follow you.
The other items are OK, I guess. One of the candidates has a slightly lower power rating than the original (600mW vs. 750mW), but these small-signal BJTs shouldn't work anywhere near the maximum power rating, right?
Thanks,
OK, got it! Just a note: now that I found it, I assume you meant "relevant Vcb", which is in the datasheets - there's no Vce reference for Cbo that I could find.
Thanks a lot!
Thanks a lot!
Good news: found the 2SC1685 today, and bought a few units.
Bad news: can't find the others at all. The store that seems to carry the 1123 haven't replied to my e-mails after a week.
I'm going to replace the 2631 with the 2N5551, and the 1123 with the 2N5401.
Any comments are welcome.
Thank you,
Bad news: can't find the others at all. The store that seems to carry the 1123 haven't replied to my e-mails after a week.
I'm going to replace the 2631 with the 2N5551, and the 1123 with the 2N5401.
Any comments are welcome.
Thank you,
So far, so good. Replaced those 3 pieces, and the power transistors. Replaced the bare wire some idiot used instead of a fuse (might have saved me a few parts if I had seen that before). Turned the power on, and it sings! Let's hope the power transistors are not fake...
Still couldn't find the courage to remove the lamp I've put in series with the power cord, though. Maybe tomorrow. I need to leave now.
Special thanks to AndrewT and SVI2004A, who helped me find my way.
Next steps are buying some new mica insulators, put the heatsink back in place, and do the calibration. I'll keep you posted.
Thanks again,
Still couldn't find the courage to remove the lamp I've put in series with the power cord, though. Maybe tomorrow. I need to leave now.
Special thanks to AndrewT and SVI2004A, who helped me find my way.
Next steps are buying some new mica insulators, put the heatsink back in place, and do the calibration. I'll keep you posted.
Thanks again,
Wrapping up
Alright, now it's working. A brief summary of the adventure:
- The power transistors were fake. First time I raised the volume, they cracked before I got to 3 - with a huge spark! I'm glad I had found that wire in the fuse holder and replaced it with a real fuse.
- Bought two more pairs (5200/1943 this time) from a different store - plus an 8A rectifier bridge to test them with this circuit: Transistores falsificados.
- The new ones passed the test, the old ones didn't (I had bought some spares). Actually, some of them burned when I applied the base current, and some even before that. They were bought from Compomil (in Brazil) - terrible experience.
- When the fakes from last week burned in the amp, I removed them and started to check voltages around, comparing the two channels - I still wasn't sure I had fakes. It turns out that I found a bad solder in a resistor's leg, and pressing the resistor against the board opened the circuit and raised the voltage at that point from ~1.2V to 47V... Fortunately that didn't fry any other parts (at least this time).
About the fuse: first time I opened this amp, many years ago, I only had the schematics. Only one fuse is shown. And there was a fuse in there, plus an empty fuse holder. I didn't bother to check all that out, because the unit was turning on, I couldn't imagine whoever serviced the unit before me would have replaced a fuse with a wire... now that I have the service manual, I noticed the two-fuse design, and realized the only fuse that was there was the 1.6A, which is for 220V. Looking closer, I found the wire in the other holder.
I hope that info is useful to someone. And I'd like to thank you guys again for your help.
I can't upload the little video I made, so you won't hear the sound. But I'm going to upload a picture instead, in case you wanna see it (sorry for the blur).
Cheers,
Alright, now it's working. A brief summary of the adventure:
- The power transistors were fake. First time I raised the volume, they cracked before I got to 3 - with a huge spark! I'm glad I had found that wire in the fuse holder and replaced it with a real fuse.
- Bought two more pairs (5200/1943 this time) from a different store - plus an 8A rectifier bridge to test them with this circuit: Transistores falsificados.
- The new ones passed the test, the old ones didn't (I had bought some spares). Actually, some of them burned when I applied the base current, and some even before that. They were bought from Compomil (in Brazil) - terrible experience.
- When the fakes from last week burned in the amp, I removed them and started to check voltages around, comparing the two channels - I still wasn't sure I had fakes. It turns out that I found a bad solder in a resistor's leg, and pressing the resistor against the board opened the circuit and raised the voltage at that point from ~1.2V to 47V... Fortunately that didn't fry any other parts (at least this time).
About the fuse: first time I opened this amp, many years ago, I only had the schematics. Only one fuse is shown. And there was a fuse in there, plus an empty fuse holder. I didn't bother to check all that out, because the unit was turning on, I couldn't imagine whoever serviced the unit before me would have replaced a fuse with a wire... now that I have the service manual, I noticed the two-fuse design, and realized the only fuse that was there was the 1.6A, which is for 220V. Looking closer, I found the wire in the other holder.
I hope that info is useful to someone. And I'd like to thank you guys again for your help.
I can't upload the little video I made, so you won't hear the sound. But I'm going to upload a picture instead, in case you wanna see it (sorry for the blur).
Cheers,
Attachments
Thanks VMat, for sharing this. And although my Spanish is on "level B" I also am happy with the "Transistores falsificados" link.
My experience with Power Transistors is to only buy them through larger and reputed channels, like for instance Farnell or Distrelec in Europe, unless your local supplier still has some NOS. Ebay - as far as I'm concerned - is something to avoid as if it were the black pest.
(Level B; B = baby)
My experience with Power Transistors is to only buy them through larger and reputed channels, like for instance Farnell or Distrelec in Europe, unless your local supplier still has some NOS. Ebay - as far as I'm concerned - is something to avoid as if it were the black pest.
(Level B; B = baby)
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