Heatsink at 2SJ109 in Aleph J

frags · 02:02 PM

Does anybody use a heatsink at 2SJ109 in Aleph J. For me it looks like this device is getting pretty hot. In the closed case with ambient temperature inside 45C the transistor case temperature reaches 70C after 1 hour. I guess junction temperature is 75-80C. Or is it OK?
I'm using PCBs from Peter Daniel where 2SJ109 is pretty close to R5 which is getting quite hot.

Additionally what was the reason to connect R5 to negative rail? It could be connected to the ground with a value of 1.7K to get the same current through the zener but the power dissipation could be three timer lower at that resistor.

Zen Mod · 10th September 2010, 03:51 PM

heatsink - if you think that's necessary

R5 - think about CMRR

frags · 10th September 2010, 04:06 PM

Zen Mod,

There is the capacitor across the zener anyway.
I'll check the behavior in a simulation software.

Thanks.

EUVL · 10th September 2010, 04:57 PM

Yes I have a 2SJ109 heatsink on my AX.

Patrick

frags · 10th September 2010, 05:06 PM

Patrick,

Could you post a picture how you've mounted heatsinks and what kind they are?

Thanks.

EUVL · 10th September 2010, 05:20 PM

Tomorrow.

Patrick

frags · 11th September 2010, 12:29 AM

I've changed R5 to 2.2k connected to the ground. As the result I got about 7C temperature drop on JFET case (from 70C to 63C in Peter Daniel's PCB) and C4 (before C4 could give a skin burn when touched). No any changes in the ripple of CCS and therefore in amplifier performance was discovered. So, highly recommended.

EUVL · 11th September 2010, 05:27 AM

TO92 has typically 80~100°C/w junction to case, so you can calculate the junction temperature from power and case temperature.

I try to keep mine below 100°C for reliability reasons.

Patrick

EUVL · 11th September 2010, 06:06 AM

As promised.

Patrick

frags · 11th September 2010, 06:02 PM

Very nice. Thank you, Patrick.

10th September 2010, 01:45 PM	#1
frags diyAudio Member Join Date: Aug 2009	Heatsink at 2SJ109 in Aleph J Does anybody use a heatsink at 2SJ109 in Aleph J. For me it looks like this device is getting pretty hot. In the closed case with ambient temperature inside 45C the transistor case temperature reaches 70C after 1 hour. I guess junction temperature is 75-80C. Or is it OK? I'm using PCBs from Peter Daniel where 2SJ109 is pretty close to R5 which is getting quite hot. Additionally what was the reason to connect R5 to negative rail? It could be connected to the ground with a value of 1.7K to get the same current through the zener but the power dissipation could be three timer lower at that resistor. Last edited by frags; 10th September 2010 at 02:02 PM.

10th September 2010, 03:51 PM	#2
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	heatsink - if you think that's necessary R5 - think about CMRR __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
heatsink for aleph 4	slr 5000	Pass Labs	6	23rd September 2010 09:06 AM
Aleph-X with 2SJ109 as input pair	h_a	Pass Labs	51	15th June 2007 08:47 PM
Heatsink for the Aleph 1.2	folkeb	Pass Labs	1	23rd January 2006 03:27 AM
Exchange: 2sj109 V for 2sj109 BL	genome	Swap Meet	0	23rd November 2005 11:36 AM
WTB: 2sj109-V or 2sj109-BL	rtirion	Swap Meet	0	18th August 2005 01:13 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

10th September 2010, 04:06 PM	#3
frags diyAudio Member Join Date: Aug 2009	Zen Mod, There is the capacitor across the zener anyway. I'll check the behavior in a simulation software. Thanks.

10th September 2010, 04:57 PM	#4
EUVL diyAudio Member Join Date: Oct 2003	Yes I have a 2SJ109 heatsink on my AX. Patrick

10th September 2010, 05:06 PM	#5
frags diyAudio Member Join Date: Aug 2009	Patrick, Could you post a picture how you've mounted heatsinks and what kind they are? Thanks.

10th September 2010, 05:20 PM	#6
EUVL diyAudio Member Join Date: Oct 2003	Tomorrow. Patrick

11th September 2010, 12:29 AM	#7
frags diyAudio Member Join Date: Aug 2009	I've changed R5 to 2.2k connected to the ground. As the result I got about 7C temperature drop on JFET case (from 70C to 63C in Peter Daniel's PCB) and C4 (before C4 could give a skin burn when touched). No any changes in the ripple of CCS and therefore in amplifier performance was discovered. So, highly recommended.

11th September 2010, 05:27 AM	#8
EUVL diyAudio Member Join Date: Oct 2003	TO92 has typically 80~100°C/w junction to case, so you can calculate the junction temperature from power and case temperature. I try to keep mine below 100°C for reliability reasons. Patrick

11th September 2010, 06:02 PM	#10
frags diyAudio Member Join Date: Aug 2009	Very nice. Thank you, Patrick.