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I have just finished by build of the 18 Watt Plexi v6

Some of the tube voltages see a little off :

V1 12AX7 P1 135.8 P3 0.895 P6 133.7 P8 0.947
V2 12AX7 P1 163.8 P3 1.659 P6 252.0 P8 163.9
V3 12AX7 P1 175.2 P2 28.6 P3 39.1 P6 168.7 P7 28.56 P8 39.1

V4 EL84 P3 12.0 P7 340.8 P9 323.8
V5 EL84 P3 12.0 P7 336.8 P9 321.8

V6 P8 20.88
V7 P8 20.88

V8 EZ81 P1 311 P3 349.1 P7 310

AC Mains Voltage 121.5
B+ Voltage 75 - 420 (VRM Min and Max)


My main concern is the voltages on V3 which all seem to be half of the expected...
everything else is within 10 - 15 %....


I will post my build pictures later this weekend...

Check the value of the resistors feeding these pins and the PI tail resistor values and that the ground on the tail resistor is very good. Resolder at ground.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Okay I finally had some time to double check the resistors and all the resistors match the layout...
I only had 1 resistor that i had to disconnect to get a valid reading...
The 470K going to the normal channel ground is basically in parallel to the 500 K pot. So basically I was reading 250K...

I also went back and remeasured the voltages :

V1 12AX7 P1 133.6 P2 NA P3 0.892 P4 Heater P5 Heater P6 132.2 P7 x P8 0.942 P9 Heater
V2 12AX7 P1 162.2 P2 NA P3 1.638 P4 Heater P5 Heater P6 250.1 P7 161.8 P8 162.0 P9 Heater
V3 12AX7 P1 172.4 P2 28.55 P3 39.18 P4 Heater P5 Heater P6 166.6 P7 28.55 P8 39.09 P9 Heater

V4 EL84 P1 NA P2 8mV P3 12 P4 Heater P5 Heater P6 NA P7 338.8 P8 8mV P9 321.6
V5 EL84 P1 NA P2 8.8mV P3 11.96 P4 Heater P5 Heater P6 NA P7 336.3 P8 8mV P9 321.0

V6 6V6 P1 NA P2 Heater P3 336.0 P4 322.2 P5 25mV P6 30mV P7 Heater P8 20.75
V7 6V6 P1 NA P2 Heater P3 334.0 P4 323.3 P5 69mV P6 73mV P7 Heater P8 20.79

V8 EZ81 P1 309AC P2 NA P3 349.0 P4 - P5 = 6.7AC P6 NA P7 310.5 P8 NA

Other Measurements :

Power Side of 250R 5W 21.14
Power Side of 150R 5W 12.15
Power Side of 8K2 2W 328.5
270K Feeding Pin 6 of Left 6V6 30 mV expected 217?
270K Feeding Pin 6 of Right 6V6 30 mV expected 220?

I am not sure what the PI Tail Resistor is? 470R through the 22K?
I have checked the grounds and they all seem to be fine....

I did move the 1M resistors from the Input jacks to V1 as per the VRM documentation.


I will have another look tomorrow to see if I can find anything weird...

Is it possible that one of the tubes is causing these issues?


Thanks for any input,
Andrew

couple of high res pictures left side right side would help

Very Clean Kit - happened to get the wrong layout and schematic, but downloaded the correct ones from the website...


VRM - How to keep your wife and neighbours happy.


Front Panel - all hardware installed - jacks on the outside to allow easier soldering.


Back Panel

Layout all the parts and get ready to solder.


Board complete... Soldered the fly wires to the bottom of the turret to try to keep the build neat...


Ground bus on the bottom of the board as well.


Wired up and tested the PT.

Wired up the Heaters.


Connect up the VRM.


Mount the Board.

Wire up the pre amps.


Finish wiring up the input jacks.


Connect the Input Jacks to V1 and the Gain to V2.


Finish V3.

Note : Originally I was connecting up the boost and cathode switch boards, but, I had an issue and went back and removed these and went back to the stock design to make sure everything works correctly... I am in the process of debugging some voltage issues and once they are solved, I will go back and try to get the boards working..

V4 & V5 EL84's an the output jacks.


V6 & V7 6V6's


Custom board - combine the boost and switch into one board..
This allows the use of an "L" bracket to hold the entire board.
(Note - I have removed this till I get the correct voltages.)


This is what the board will eventually look like...
NOTES : The next time i make one of these boards, i will turn the relay 90 degrees so that it does not hit the turret board...

Tubes in ready for a voltage check.


Current state of the build.


Head and Cabinet.


Back of the Head and Cabinet.

This was my third build of a Trinity Amp...

I started with a Triwatt a couple of years ago and then build the Tweed this spring...
I completed the 18 Watt last weekend and took it to my guitar lesson to allow my teacher to check it out....

He thinks that the Plexi is the best of the three that I have made... the Normal channel is so clean and still on the edge...
And the TMB can be in your face pure rock and roll...

He wants me to build him a Plexi 1x12 combo... maybe that will be the next winter project...

Hopefully, I can determine why the voltages are not quite right, but it sounds great the way it is too....

Thanks,
Andrew

Those are the grids so the voltages should be very low with no signal.

Our voltages are referenced to JJ tubes and they can be quite dIfferent. If it sounds good, it should be OK!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I bought a complete set of electro-harmonix for the start up incase something went wrong...

I have a set of TAD 6V6 and a set of Mullard EL84, and a Mullard 12AX7 and a Tesla EZ81 when everything checks out...

Thanks for the info on the voltages...

I plan on starting to work on the boost board again next weekend...

Great looking build, Andrew! Just finished my Plexi v6 build as well. Resolving some issues right now with the 6V6 cathode voltages, but the amp sounds really good! Still need to install the VRM (I wanted to build it "stock" first to be sure everything was working correctly). How is the VRM working for you?

I'm running mine into an Avatar Vintage oversized semi-open back 2x12 with Heritage 20W Greenbacks in it. Cab looks similar to yours. I'll post up some pics once I get everything finished.


-Tom

I think the issue is coming from the voltage readings in the layout. The bublles are pointing to the 270k grid leaks where they should be pointing to the 100k plate resistors

I used the VRM in my Tweed build as well....
My wife allows me to play guitar as long as I don't break any china or windows...
The VRM allows me to play the amp at lower volumes and still have the sound I crave...

Take care,
Andrew

nice build dude... looks really tidy in those cabs!

_________________
Corey