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For some reason I am getting my B+ voltage on the plate pins of all power, PI, and Preamp tubes instead of the ballpark values shown in the Trinity 18 Voltage Chart.

I am building an 18 watt sIII with an installed VRM module and the 120 Volt power configuration. At this point I am finished all soldering and assembly steps.

Results for the "Test Power Supply" section on page 46 of the manual seem normal:
121.4 VAC across N and L IEC mains socket
121.4 VAC across indicator terminals
7.0 VAC across all heater wires of Rectifier, Power, PI and Preamp tubes
643 VAC across pins 1 - 7 of Rectifier socket

Under the "Making a Voltage Measurement" section on page 67 near the bottom of the page it states:
"With no rectifier in place, apply power and test the High Voltage AC and ensure that it is on the correct pins of the rectifier and in the correct voltage range (290 VAC)." How do I perform this test with my meter? It sounds like the same test as already completed where you measure VAC across pins 1 - 7. I measured 643 VAC and not 290 VAC as suggested???

I moved on to the next test, on page 67, where I installed the EZ81 rectifier tube. I powered up for 10 seconds then turned on the standby switch. B+ was 436 VDC at the first 1.5K 5W resistor and 440 VDC at the rectifier socket (pin 3) which seems normal.

Next I moved on to testing the plate voltages on the other power (pin 7), PI and preamp (pins 1 and 6) tube sockets. My results were between 437 - 439 VDC (aka B+ voltage) on every one of these plate pins. I believe something is wrong so I stopped testing at this point.

438V DC with the recto installed is good

Now did you install all the other tubes when reading the plate voltages on the other tubes? With the other tubes (preamp and output tubes) installed the amp won't be "loaded down" and you'll see weird high voltages across the amp.

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http://pdfelectronics.com

See my attachment with the testing procedure. In this step only the rectifier tube should be installed.

If you only have the recto in the voltages are all going to be high and really mean nothing

Add the other tubes, hook up a speaker and test voltages again.

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http://pdfelectronics.com

How do I test for the 290 volts on pin 1 and 7 of the rectifier tube. Do I check each of these pins for a DC voltage using a chasis ground? Or do I check between pins 1 and 7 for an AC voltage? (this measurement was 643 volts for me)

You are testing for AC

If you measure from pin 1 to pin 7 (i.e. one DMM probe on each pin) you will read ~580V AC.
If you measure pin 1 to ground or pin 7 to ground (i.e. one DMM probe on pin 1(or 7), the other probe on ground) you will read ~290V AC.

643V AC is close enough to 580V, assuming you were measuring from pin 1 to pin 7. The amp does not have a load so the voltages will be high until you connect the rest of the tubes/speakers.

_________________
http://pdfelectronics.com

I plugged in all the tubes and the voltage measurements were then within expected ranges. I successfully got a 293 VAC reading for both rectifier pins too. I would have responded sooner but I was too busy jammin with my guitar and working amp!!! Thanks for the assistance.

Now it's time to order that Trinity combo cabinet. ;-)