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Old 23rd October 2003, 02:32 AM   #1
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Default Lectron JH50 help

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
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Old 23rd October 2003, 04:27 PM   #2
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Hi,

Quote:
It is regulated using discrete transistor, but they have erase all the parts number. The driver tubes were 6SJ7 and 6SN7.
The drivers are fed from the regulated 400V rail, the output tubes are fed from the same rail but are fed the unregulated 435V.

Unfortunately I have no idea what the semiconductor in the regulator is.

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Old 24th October 2003, 08:01 PM   #3
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Thank you Frank, you are very helpful

Regards
Thomas
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Old 26th October 2003, 06:58 PM   #4
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Default JH50 Supply

I owned a JH50 with the same problem, it seems they had a lot of problems with the solid state psu Jean Hiraga sent me details of the passive design he later used, I'll dig deep and see if I still have the info 9must be 8 years ago!)

Mozfet
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Old 26th October 2003, 08:43 PM   #5
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Hi,

Quote:
Hiraga sent me details of the passive design he later used, I'll dig deep and see if I still have the info 9must be 8 years ago!)
By passive I assume you mean a choke?

Cheers,
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Old 26th October 2003, 11:59 PM   #6
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Default 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?
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Old 27th October 2003, 12:01 AM   #7
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Default Screen Supply?

I think it was the screen supply!!

I'll shut up till I find the info!

Mozfet
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Old 27th October 2003, 12:10 AM   #8
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Hi,

Quote:
All the information was in French and the circuit diagrams
French is no problem, it's my mother tongue...amongst others...

I can easily translate it for you.

Cheers,
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Old 27th October 2003, 02:24 AM   #9
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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
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Old 27th October 2003, 01:21 PM   #10
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Hi,

Quote:
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
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.

Quote:
The driver regulator board is fed from the first smoothing caps and it is measured 4"x5"
On the circuit diagram the regulator is fed from the last cap, not the first.

Quote:
The screeen regulator board measured 4" x 1 1/2" and I think it is fails also.
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.

Quote:
Is it possible this is because of the screen voltage is to high?
It's certainly possible, you have no current flowing with a dead tube.

Cheers,
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