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Old 20th June 2010, 08:58 PM   #1
LFM is online now LFM  Canada
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Default 400A VU meter

I have a 400A which I bought new in 1980. It has been in regular use since then. Recently one LED in the peak meter display stopped working. I searched this forum and it seems that the fault is with the LED or capacitor which has dried out. Can anyone tell me what the proper replacements are so i can preorder them. I swear I remember seeing a hand drawn schematic for these meters here but I can't find it. If anyone can point me to it I would appreciate it.
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Old 20th June 2010, 09:15 PM   #2
Zen Mod is offline Zen Mod  Serbia
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is that this schmtc ?

which LED stopped working ?

anyway - as I see it - it's either cold solder joint , or dead OP section , or dead LED itself

in any case - easy to repair

check conductivity of LED with diode test on your DVM ; if not -

check for cold solder joints with magnifier or just reflow all suspicious ones ; if not -

replace adequate OP
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Last edited by Zen Mod; 20th June 2010 at 09:20 PM.
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Old 21st June 2010, 12:18 AM   #3
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Default 400A meter

No Zen, thats not the one. My amp has 2 rows of LED's per channel labelled Peak and Average. The -15 LED is not working on the right channel Peak meter. The - 15 on the average meter ladder is fine. The LED seemed to fail after not using the amp for a month or so. That and the age of the amp are why I thought it might be a cap. I can check the LED and reflow the solder joints but it would be really nice to have the proper replacement LED on hand.
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Old 21st June 2010, 01:05 AM   #4
Zen Mod is offline Zen Mod  Serbia
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LED is certainly generic one ;

if failed - you can always replace it with top most one , and place new ( even if different in glow ) on that top most position

anyway - troubleshooting procedure is same , even if schematic isn't exact one
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Old 21st June 2010, 09:51 PM   #5
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The LED on my NS-10 stopped working - I just replaced it with one I have had around since - ehhh 1980. The original one just had reached its end of life. Just try to solder in a new one.
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