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-   -   help with Luxman l-200 (http://www.diyaudio.com/forums/solid-state/222619-help-luxman-l-200-a.html)

Kermit100 1st November 2012 12:49 AM

help with Luxman l-200
 
Greetings!
I recently aquired a luxman l-200 and what i need help with is how to change the bulb to a l.e.d and what parts i need to modifiy with the associated circuit.
Thanks in advance!

Kermit100 7th November 2012 06:48 AM

bump! i want to fix this soon so i can enjoy this musical beast!

RS232 7th November 2012 06:52 PM

Well if the supply for the bulb is AC you going to need:
1 diode (any 1N400*)
1 resistor to set LED current
1 diode of your choice
If it is DC you don't need the diode

Ric

vynuhl.addict 2nd February 2013 04:40 AM

The Luxman runs the lamps from 20v dc rails, negative supply if I'm correct. Even if it were ac you could still use the led since regardless of its orientation it will conduct on either the positive or negative half of the ac pulse just like any diode. You however will need to observe the voltage from the rail and use a current limiting resistor. I just refurbished an l235 but changed to amp circuit to incorporate nested feedback and a better power supply. It's a good little amp, but miles away from my Current Feedback open loop design.


Colin

Art M 2nd February 2013 06:03 AM

Quote:

Originally Posted by vynuhl.addict (Post 3352474)
The Luxman runs the lamps from 20v dc rails, negative supply if I'm correct. Even if it were ac you could still use the led since regardless of its orientation it will conduct on either the positive or negative half of the ac pulse just like any diode.Colin

If you reverse Bias an LED, failure is eminent. The Avago HLMP series is
rated for 5V@100uA (some brands rated at 10uA) maximum reverse voltage. Reverse it at 20V and you will probably will soon have a Blown diode.

vynuhl.addict 2nd February 2013 08:24 AM

That's why you implement a dropper resistor, this will knock down the voltage, all you need to do is measure the rails and adjust accordingly for a decent bias, 4ma is sufficient or lower if you want a duller brightness. It's crude but it will work, however yes on the reliability factor dc will function better. A simple low power 1n4148 is sufficient for such low power.


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