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Old 3rd October 2013, 06:08 PM   #1
davym is offline davym  Europe
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Default JC-2 Clone Build

Hi, i hope this is the right place to post pictures of my build, please let me know if not and i'll remove them. Sorry about the poor quality, it seems the more i take the worse they get.

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Old 3rd October 2013, 06:14 PM   #2
davym is offline davym  Europe
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I have not connected up the volume pot because i have an external pot and source selector. I would like to get the power switch to illuminate, it has an LED and resistor built into it and it's rated at 6V, i have a bridge rectifier which i could fit to get DC from the supply transformer but i dont want to pull the voltage down on one rail. Any suggestions please?
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Old 6th October 2013, 10:39 AM   #3
davym is offline davym  Europe
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Can someone please suggest a way to tap into this preamps power supply so that I can get the power switch to light up. There must some way I can do this.
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Old 6th October 2013, 10:46 AM   #4
drahcir is offline drahcir  Philippines
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i don't know if your switch is the same as the rocker switch,wherein it has 3 legs. you can test it first with a multimeter to see which legs are shorted when you press the switch and the non shorted one must be connected to ground for the LED to lit.

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Old 6th October 2013, 11:02 AM   #5
davym is offline davym  Europe
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The switch is wired up and works fine as a power on/off for the amp. It has a separate pair of terminals marked + & - for it's internal LED which is labelled 6v (it has a resistor built in with it) it only needs around 250ma to light up but I can't work out how to tap into the amp to get this supply current.

I tried posting a link to it but for some reason this forum wont allow links to ebay.
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Old 6th October 2013, 11:04 AM   #6
AndrewT is offline AndrewT  Scotland
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Does the "Lite" switch have 4 or more tags for connections?
The LED Lite may have two separate tags for the DC supply to the LED. The LED may have a current limiting resistor built into the switch.
The "mains" connections on the switch should have two sets of normally open 250Vac rated contacts, one for Live and one for Neutral. It is normal for these to NOT be connected to the Lite.

The somewhat old fashioned "neon" indicator is very different in that it needed high voltage and would work off AC.
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Old 6th October 2013, 11:07 AM   #7
AndrewT is offline AndrewT  Scotland
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250mA seems far too much.
More like 1 to 3mA is all that would be necessary for each LED inside the switch.
Simply tap off the DC supply to the amplifier. Add an extra current limiting resistor for the much higher voltage than the specified 6Vdc.
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Old 6th October 2013, 11:15 AM   #8
davym is offline davym  Europe
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The JC-2 clone kit's supplier (Jims Audio) just got back to me, he says to tap into the positive rail and use a 1.2K resistor, it as well as the one built into the switch should lower the current enough apparently. I was concerned about pulling that rails voltage down but as there is a trim pot to set the rail voltages so I can probably compensate for this quite easily.
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Old 6th October 2013, 04:17 PM   #9
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Hello, You might try running the light from one rail to the other.
That way the voltage drop will be equal on both rails.
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Old 6th October 2013, 07:13 PM   #10
davym is offline davym  Europe
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Success! I did not have a 1.2K resistor so I tried a 1.4K and got a great result. I was able to compensate for the 0.2V drop it caused by adjusting the trim pot for that rail.

I cant remember who told me that the LED and inbuilt resistor needed 250mA to work properly but I did think it was excessive at the time.

All in all a good result and I am still amazed at how good this very cheap kit sounds.
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