Voltage reading off, Basic Crack

[clams]

Hey everyone,

I just finished building my amp and had these voltages off. Also one of the LEDs was off. I reflowed the joints connecting to all the problem terminals but the voltage readings are the same. Is this a damaged LED? i've tried to measure the resistance of the LED that is off but my ohmmeter reads "overloaded"

Terminal	Measured Voltage	Expected Voltage
1	153V	90V
6	90	0
7	150V	100V
10	40V	0V
A6	152V	90V
A8	12.4V	1.5V

Thanks for any help!

 

[Paul Joppa]

Sounds like the LED is either busted or backwards.

 

[clams]

I checked and its in the correct orientation. Would a broken LED really have the potential to throw off all of those voltages?

 

[Paul Joppa]

If you have more than 1.5-1.6 volts at A8 (and A3) then the respective LED is not conducting. Either it is backwards, or it is not soldered successfully, or it is damaged. In that case, the driver plate voltage will be very high, and that is connected to the output tube grid which will be high, causing the output cathode to be very high and the current to be too high, which drives the power supply voltage down a bit.

Yes, it messes up everything.