LED not Lighting Up

undertowogt · 9976

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Offline undertowogt

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on: August 07, 2010, 05:42:02 PM
Hi,
Does anyone have any idea why the LED from B 8 Socket Terminal would not light up. This is the LED coming off the tube socket attached to the Ground Plan. I have changed LEDs and the replacement does not light up either. The LED from Socket Terminal 3 to 9 Lights up just fine

Both Tube Light up and 3 out of for LED light Up.
unfortunate I have a large hum though the whole unit when plugged in.
I am just looking for a place to start to trouble shoot

Any though would be appreciated.

Thanks,
newbie builder
« Last Edit: August 08, 2010, 07:29:15 AM by undertowogt »


Offline Paul Birkeland

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Reply #1 on: August 08, 2010, 08:00:20 AM
If the LED doesn't light up at B8, and it is oriented properly, this is a sign that no  voltage is getting to the plate (B6).  With the unit on, measure the DC voltage at B6.  If there is no voltage there, measure the other side of the 220 ohm carbon composition resistor that is attached to B6.  If there is no voltage there, then you assuredly have a bad solder joint on one side of the larger carbon film plate load resistors (22k IIRC). 

Have a look and let us know.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline undertowogt

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Reply #2 on: August 08, 2010, 01:50:27 PM
Ooh no.................

Turned the unit on to do the above and it started to SMOKE!!!!! from the Bridge rectifier. It was not smoking before. Looks like I have more issues than I thought.


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