Technics SU-V8 replacement for 2SC2632/2SA1124 - constant current and pre drive

Jump to Latest
#22
Hi Cosmin and Everyone,

The lights would be cool,however still look great without them. I'd like a V909

Good news, the silver V8, passed the dim bulb test, and i let her sit idle for 5mins. Should be safe to proceed with adjustments

I wonder if i skip the dc balance and go straight to clamp and icq settings. I fire up the amp each procedure to make sure i have no slip on the clips. I power up the amp with leads attached and turn the DMM on at about 10mins. Finish off with dc adjustment to 0mv.

Another issue manual says between R651 and ground. I assume its the speaker end of R651 as in images below, or the front end of the resistor.
P1470932.JPG



Manual points to the back of the resistor
resistor dc offset.jpg


Thanks , Kind Regards Sam 🙂
 
#24
MaccAu said:
View attachment 1159399

Hi, I used the 2SC2632 in my black SU-V8. These parts are well gone, and though they appear on sites like yahoo auctions, the shipping is high, and then its not known if they are real or hot, though some looked really like the old parts My silver SU-V8 is now in need of replacements.

Following a bit of search around DIYAudio forums, i came up with 2 possible replacements. I can only get D version in the KSC series, frequency is the same not the Hfe

KSA1381ESTU
https://au.mouser.com/datasheet/2/308/1/KSA1381_D-1810601.pdf

KSC3503DSTU
however the matching pair is D spec not E (which appears to be discontinued)
https://www.onsemi.com/pdf/datasheet/ksc3503-d.pdf
So that concerns me re the specs, though both have good frequency like the old

I got another pair of transitors also
2N5551 PBFREE/ 2N5401 PBFREE
https://my.centralsemi.com/datasheets/2N5550_2N5551.PDF
https://au.mouser.com/datasheet/2/68/2n5400_5401-1518545.pdf

Old parts
https://alltransistors.com/adv/pdfview.php?doc=2sc2632.pdf&dire=_panasonic

Thanks
Sam
I have the above from my order from Mouser, just not sure which is best

@Iomis Hi Cosmin, its Sam, you may remember me, i think you said you had a Technics SU-V8, did you need to change your transistors, ones above i have from my order

​

Click to expand...
hello.i repaired this amp,its working ok but those transistors 2SC2632/2SA1124 at vas and current source dissipate around 440mw and get quite hot even now at winter with a room temperature of 20 celcius.i am afraid to use it at summer due to high temperatures. i have ksa1381e and ksc3503d. ksa1381e is a good replacement for 2sa1124 but ksc3503d has a lower gain classification. i was thinking of using ksa1381e in place of 2sa1124 as vas stage and TTC004B in place of 2sc2632 as a current source.what do you think?
 
  • Like
Reactions: MaccAu
#25
Hi,

My friend repairs amplifiers , instead of 2SC632 /2SA solder 2SC2910S - 2SA1208S.
Here is what he wrote to me about 2SC2910S / 2SA1208S:


High-quality components - in most cases can replace PANASONIC 2SC2632R,S / 2SA1124R,S and 2SC2631R,S / 2SA1123R,S, which are no longer produced. They probably work in differential stages, as pre-drivers and current sources. Assemble without shortening the leads.
-small gain spread hfe, high ft

My offer:

https://www.diyaudio.com/community/...sonic-nichicon-diodes-ic-socket.407559/latest

https://www.diyaudio.com/community/threads/ksc2690-ksa1220-8-sets-for-sale.407135/latest

https://www.diyaudio.com/community/...rchild-nos-transistors-for-sale.401076/latest

Robert
 
  • Like
Reactions: MaccAu
#26
maouna said:
hello.i repaired this amp,its working ok but those transistors 2SC2632/2SA1124 at vas and current source dissipate around 440mw and get quite hot even now at winter with a room temperature of 20 celcius.i am afraid to use it at summer due to high temperatures. i have ksa1381e and ksc3503d. ksa1381e is a good replacement for 2sa1124 but ksc3503d has a lower gain classification. i was thinking of using ksa1381e in place of 2sa1124 as vas stage and TTC004B in place of 2sc2632 as a current source.what do you think?
Click to expand...
Hello Maouna,
I think my V8 issue is not the transistors as i tried others without luck. I would invest in heatsink for your V8s transitors. I got some fo my V4x which also has the same transistors, however the V8 pre drive board does not leave much room. Check back a page Cosmin had a vertical heatsink. Mouser or Digikey or Element14 might have some or use the ones i got and maybe bend them to fit. I can your summers are probably like mine here in Australia, very warm at times. That concerned me also the lower gain for the KSC3503d transistor. I am not good with advice on these parts, Cosmin had the toshibas in his. I think for now, look for heatsinks to help the transistors cool

​

@FANMUSIC
Thank you Robert, that is good to know, however for now my issue is somewhere else with the amplifer.
 
You must log in or register to reply here.
Top Bottom