★★ Free PCB for JLH 2005 Class-A Amplifier

[stk435]

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.

 

[AudioSan]

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]

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]

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]

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]

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]

how many watts does this amp have ?

 

[siliconray]

10W

 

[killmister]

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

 

[haiduc32]

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.

 

[lduarte1973]

can you make a assembled power amp with case and supply included for this board ?

Marantz HDAM Design 200Wx2 Class A HiFi Amplifier SRH-02 - Boards | Kits | Components | Modules | Tools

 

[siliconray]

Hi lduarte1973, sorry we don't make finished amp for this design.

 

[lduarte1973]

but do you sell them : case,supply and heatsink ?

 

[siliconray]

there's power supply here:
Free Power Supply PCB For JLH Amplifier - Boards | Kits | Components | Modules | Tools

RE3213H is suggested for this amp:
Enclosure RE3213H 320x130x311 - Boards | Kits | Components | Modules | Tools

 

[AudioSan]

he was asking for PSU and chassis for the 200W marantz modules

 

[lduarte1973]

yes , i was , for the 200w marantz

 

[siliconray]

Oh sorry. the case could be custom made. Something like RE4821H could be used for it. 500W+ toroide transformer could be used as power supply. Shipping cost would be horrible

 

[SomekPoland]

Will MJE3281 do the trick?

 

[haiduc32]

hi,
just wanted to drop by and say that I finally got my amp working. in my last post I said that one channel is louder than the other, after re-soldering some transistors and a new pair of capacitors nothing changed so I switched the channels and got the same results, conclusion: the pair of speakers that I used for tests were buggy. put it on my 8ohm tannoy and everything sounds wonderful.
here's a pic. thnx to to all who helped a noob like me get into diy audio.

An externally hosted image should be here but it was not working when we last tested it.

 

[siliconray]

congratulations!