Does anyone knows the output power supply voltage for the driver board of Lectron Lectron JH50 amplifier (Jean Hiraga design)?
It is regulated using discrete transistor, but they have erase all the parts number. The driver tubes were 6SJ7 and 6SN7.
The idea is I will built the new regulator to replace the old one, but I don't know the output voltage to the driver and screen since mine were broke.
Thank's
Thomas
It is regulated using discrete transistor, but they have erase all the parts number. The driver tubes were 6SJ7 and 6SN7.
The idea is I will built the new regulator to replace the old one, but I don't know the output voltage to the driver and screen since mine were broke.
Thank's
Thomas
No Choke
No choke and to be honest I dont recall if it was for the main HT supply or a lower current drain supply but it did replace a circuit board (which I may still have) the PCB was about 3 X 4 inches. I have not had a chance to search my files yet. All the information was in French and the circuit diagrams of the old active circuit did not have part numbers either as I was thinking of rebuilding it, however JH was clear that the passive circuit was sonically superior, hence it made the excercise rather pointless.
Mozfet
Just remembered there were two (black electrolytic) capacitors on the PCB which were custom made for Lectron. do you know which board this is?
No choke and to be honest I dont recall if it was for the main HT supply or a lower current drain supply but it did replace a circuit board (which I may still have) the PCB was about 3 X 4 inches. I have not had a chance to search my files yet. All the information was in French and the circuit diagrams of the old active circuit did not have part numbers either as I was thinking of rebuilding it, however JH was clear that the passive circuit was sonically superior, hence it made the excercise rather pointless.
Mozfet
Just remembered there were two (black electrolytic) capacitors on the PCB which were custom made for Lectron. do you know which board this is?
Dear all,
I try to describe the JH50 original circuit which I drawn from the amplifier.
The raw DC from rectifier were smooth using 2 cap 220u-400V in series followed by choke then another 2 cap 500u-400V in series
which fed the screen regulator board and to both output transformers.
The driver regulator board is fed from the first smoothing caps and it is measured 4"x5"
I already try to repair this board but I can not get 400V from it.
I just think to replace it with a simple RC filter. Maybe this is what you mean by passive circuit.
The screeen regulator board measured 4" x 1 1/2" and I think it is fails also.
I measured full DC 435V output from it. I remember one of the EL34 is failed in this amps.
Is it possible this is because of the screen voltage is to high?
regards
Thomas
I try to describe the JH50 original circuit which I drawn from the amplifier.
The raw DC from rectifier were smooth using 2 cap 220u-400V in series followed by choke then another 2 cap 500u-400V in series
which fed the screen regulator board and to both output transformers.
The driver regulator board is fed from the first smoothing caps and it is measured 4"x5"
I already try to repair this board but I can not get 400V from it.
I just think to replace it with a simple RC filter. Maybe this is what you mean by passive circuit.
The screeen regulator board measured 4" x 1 1/2" and I think it is fails also.
I measured full DC 435V output from it. I remember one of the EL34 is failed in this amps.
Is it possible this is because of the screen voltage is to high?
regards
Thomas
Hi,
From what I can tell reading "L'Audiophile" issue #41 (old series):
- diode rectification followed by a resistor in both legs.
- cap, choke (5H), 2 caps in //, resistor, 2 more caps in // > to reg.board.
When I look at the picture of the amp with the hood removed that's what I can see as well.
On the circuit diagram the regulator is fed from the last cap, not the first.
There is no screen regulator. You probably mean the fixed bias for the grids of the EL34s?
G2 is resistively couled to the anode of the EL34.
G3 is grounded.
It's certainly possible, you have no current flowing with a dead tube.
Cheers,
From what I can tell reading "L'Audiophile" issue #41 (old series):
- diode rectification followed by a resistor in both legs.
- cap, choke (5H), 2 caps in //, resistor, 2 more caps in // > to reg.board.
When I look at the picture of the amp with the hood removed that's what I can see as well.
On the circuit diagram the regulator is fed from the last cap, not the first.
There is no screen regulator. You probably mean the fixed bias for the grids of the EL34s?
G2 is resistively couled to the anode of the EL34.
G3 is grounded.
It's certainly possible, you have no current flowing with a dead tube.
Cheers,
Dear Frank,
I am very sure it was a screen regulator in my amps.
It is a small PCB place on the power supply board .
If the G2 is resistively coupled to anode then this amps is running in triode mode. But mine were in pentode mode.
There is no regulator for fixed bias, It is only a simple RC to do this job.
Maybe JH have made several modification in their Lectron production.
Regards
Thomas
I am very sure it was a screen regulator in my amps.
It is a small PCB place on the power supply board .
If the G2 is resistively coupled to anode then this amps is running in triode mode. But mine were in pentode mode.
There is no regulator for fixed bias, It is only a simple RC to do this job.
Maybe JH have made several modification in their Lectron production.
Regards
Thomas
Lectron Driver Board
The output of this driver supply board is 365v.
The small can transister that fails on the passive driver supply board can be replaced with a Tip-50. This is the can that has the star type heat sink on it. I've done this substitution and it works great. It just drops in with no other modifications. Careful you get the Tip-50 oriented right. Leads must be bent into unnatural positions. Small heat sink is adequate.
This whole passive driver supply board is inferior to an active current source/shunt regulated supply I installed several years ago. It took the amp to the next level. This was a kit, and I forget the manufacturer, but I'll look it up if anyone is interested.
The 6SJ7s in the input stage are a major weak link in this amp. NOS RCAs or Sylvanias sound best. I have completely replaced this tube on my amp with a 6DJ8 variant called the 6N1P. This is a dual triode, and I use only one side per channel. Paralleling degrades performance. Sonic improvement is huge. There is an overall reduction in negative feedback in this approach, so don't do this if you want to run the amp at high power.
The output of this driver supply board is 365v.
The small can transister that fails on the passive driver supply board can be replaced with a Tip-50. This is the can that has the star type heat sink on it. I've done this substitution and it works great. It just drops in with no other modifications. Careful you get the Tip-50 oriented right. Leads must be bent into unnatural positions. Small heat sink is adequate.
This whole passive driver supply board is inferior to an active current source/shunt regulated supply I installed several years ago. It took the amp to the next level. This was a kit, and I forget the manufacturer, but I'll look it up if anyone is interested.
The 6SJ7s in the input stage are a major weak link in this amp. NOS RCAs or Sylvanias sound best. I have completely replaced this tube on my amp with a 6DJ8 variant called the 6N1P. This is a dual triode, and I use only one side per channel. Paralleling degrades performance. Sonic improvement is huge. There is an overall reduction in negative feedback in this approach, so don't do this if you want to run the amp at high power.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.