JLH 80w mosfet power amplifier - modifying it

[AndrewT]

You will find the JLH amps on this site and links to all his amplifiers.

 

[anarack]

Hi thanks, I have already found the correct circuit digs, but I am really after PCB etch diags which will save me potentially having to strip my existing pcbs if I can find them as I seem to remember they might be double sided?

 

[jamesfeline]

Hello

I have all parts for this kit including all the hard to find transistors .. and I have both the power supply and amplifier PCBS

I can put some on ebay or please pm me if interested .. the power amplifier is double sided


regards

 

[jamesfeline]

I also have the original BF870 & VN transistors

 

[jamesfeline]

the pcb's that I have are new old stock never been used

best regards

 

[nigelwright7557]

I found with a similar circuit I got a bit of 50Hz hum with no input signal.
So I decoupled the front end of the amp (both phases) with 39R and 220uF and this made the amp dead silent with no input signal.

 

[jamesfeline]

Hello .. just to let you all know that I will start a separate JLH 80w build thread in a few days time, as I have thousands of original 2N5459 / BF870 / VN1210M transistors so might as well use them .. regards Nick

 

[adsmith]

James, did you ever start a new JLH 80w build thread ?

Do you have any Hart PCB's still, if so which ones and would you be willing to sell some ?

Thanks Gavin

 

[jamesfeline]

James, did you ever start a new JLH 80w build thread ?

Do you have any Hart PCB's still, if so which ones and would you be willing to sell some ?

Thanks Gavin

I can do if people are interested .. I have all the PCB's power amplifier & power supply
and all the hard find transistors such as the BF870 so can supply 4 PCB's for a stereo pair with the BF870 transistors .. I will check to see what I have

regards

 

[jmartinbaugh]

I am having to sell my JLH Hart Kit Power AMP due to failing health. I have part built Hart power supply PCB and two Hart Power Amp PCB,s I started rebuilding them some time ago and have most components to completer. Two sets of power Transistors and Capacitors. Is anybody interested?

 

[tonewheelkev]

Thanks vac231

Thanks vac231....after struggling for some months now, followed your instruction to remove(suppress!) 3 wire links....and BINGO....at last, a PSU that works correctly...and without the 15vBar Graph circuitry😀😀😀

........Suppress the following components :


R44, R45, R47, R48, R49, R50;
C13, C14;
D34, D35;
Q23, Q24;
the 3 links that are placed between C11 & C12.

After this mod, there is only three components left in the zone : the link next to C14 and, of course, C11 & C12!

Nicola

 

[Mark1001]

A question related to the Hart JLH 80 watt amplifier, can a supplier be advised for the selector switch?


Thank you.
Mark