★★ Free PCB for JLH 2005 Class-A Amplifier - Page 11

stk435 · 12th December 2012, 01:53 AM

folks, Can you please help me out here. This is my second diy project and struggling to get this to work. I am using the silicon ray 2005 jlh board with their PSU, i am measuring negative 26 volts on my output.
I am using MJ15003 for output, BD139/140 and BC560
replaced all the transistors one full round with no results. Any help will be much appreciated.

AudioSan · 13th December 2012, 06:18 AM

so you got full negative supply rail on the output? start with confirming thet the PSU is working. du you got +/-26V or there about?

AudioSan · 5th January 2013, 01:14 AM

he asks for help. but do not visit the tread for over 20 days after asking for help. that tells me he realy don't want help. so i'm out of it.

haiduc32 · 11th January 2013, 04:34 PM

Hi,
so finally I've assembled my very first amplifier, and my very first JLH amplifier. After putting it all together in a chassis I've figured that the left channel is louder than the other. I assumed it could be corrected with VR2, but nothing changed.
As a background, I might have used some transistors from a different batch on the second board.
Is it possible to adjust the board from the VRs, or should I resolder all transistors to be from the same batch?

thanks

killmister · 05:42 PM

Hi
I f you can measure HFE, match the transistors between left and right especially for the input transistor..
You can't adjust the unbalance with vr2.
Can you post the shema ?

siliconray · 12th January 2013, 11:01 PM

The gain is determined by the feedback network so I think the HFE of transistors won't affect it very much. I think haiduc32 should check the soldering first. For example, the fault soldering parts at the input stage will affect the loudness.

VR2 is used to adjust the 0 point, don't adjust it when it's balanced!

lduarte1973 · 12th January 2013, 11:33 PM

how many watts does this amp have ?

siliconray · 12th January 2013, 11:59 PM

10W

killmister · 13th January 2013, 06:41 AM

Mine is 16 watts . Psu is 32v and bias current 1.5A.

haiduc32 · 13th January 2013, 06:33 PM

hi,
thanks for the replies, I don't have a DMM with HFE so no way to pair the transistors. I think I'll try to resolder the second board with transistors from same batch and see if that works out, but that'll be possible only in 2 weeks, I'll post back when I try.

12th December 2012, 01:53 AM	#101
stk435 diyAudio Member Join Date: Sep 2012	Negative rail in output folks, Can you please help me out here. This is my second diy project and struggling to get this to work. I am using the silicon ray 2005 jlh board with their PSU, i am measuring negative 26 volts on my output. I am using MJ15003 for output, BD139/140 and BC560 replaced all the transistors one full round with no results. Any help will be much appreciated.

13th December 2012, 06:18 AM	#102
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	so you got full negative supply rail on the output? start with confirming thet the PSU is working. du you got +/-26V or there about? __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers

5th January 2013, 01:14 AM	#103
AudioSan diyAudio Member Join Date: Feb 2009 Location: Trondheim	he asks for help. but do not visit the tread for over 20 days after asking for help. that tells me he realy don't want help. so i'm out of it. __________________ aleph P1.7 pre. F5 power amp. CDpro2(need DAC). Vivaldi8 speakers

11th January 2013, 05:40 PM	#105
killmister diyAudio Member Join Date: Dec 2009	Hi I f you can measure HFE, match the transistors between left and right especially for the input transistor.. You can't adjust the unbalance with vr2. Can you post the shema ? Last edited by killmister; 11th January 2013 at 05:42 PM.

12th January 2013, 11:01 PM	#106
siliconray diyAudio Member Join Date: Sep 2011	The gain is determined by the feedback network so I think the HFE of transistors won't affect it very much. I think haiduc32 should check the soldering first. For example, the fault soldering parts at the input stage will affect the loudness. VR2 is used to adjust the 0 point, don't adjust it when it's balanced! __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me


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11th January 2013, 04:34 PM	#104
haiduc32 diyAudio Member Join Date: May 2012	Hi, so finally I've assembled my very first amplifier, and my very first JLH amplifier. After putting it all together in a chassis I've figured that the left channel is louder than the other. I assumed it could be corrected with VR2, but nothing changed. As a background, I might have used some transistors from a different batch on the second board. Is it possible to adjust the board from the VRs, or should I resolder all transistors to be from the same batch? thanks

12th January 2013, 11:33 PM	#107
lduarte1973 diyAudio Member Join Date: Feb 2009 Location: Lisbon	how many watts does this amp have ? __________________ Hey ! just because i´m going bald doesnt mean i cant like hair metal

12th January 2013, 11:59 PM	#108
siliconray diyAudio Member Join Date: Sep 2011	10W __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me

13th January 2013, 06:41 AM	#109
killmister diyAudio Member Join Date: Dec 2009	Mine is 16 watts . Psu is 32v and bias current 1.5A.

13th January 2013, 06:33 PM	#110
haiduc32 diyAudio Member Join Date: May 2012	hi, thanks for the replies, I don't have a DMM with HFE so no way to pair the transistors. I think I'll try to resolder the second board with transistors from same batch and see if that works out, but that'll be possible only in 2 weeks, I'll post back when I try.

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