trinityamps.com

When I built the prototype Triwatt I initially had a problem like this. Turned out I'd missed a couple of wires connecting the PI to the power stage. My hunch is that there's probably a missed connection here as well. So my advice is to do a double re-check. Also, while checking the voltages on the power tube pins, you should hear some clicks and pops as you go around between the pins. That will tell you whether or not the power stage itself is functional.

_________________
Great tones come in small glass jars!

Stew, Phil, & Stephen thanks for the help!

I will try your recommondations tonight after work.

I can say that the next amp I build, in the future, will most likely be a Trinity 18. (Unless you are doing a JTM45 by then! - I have 3 sets of both EL84s & El34s that need an amp) Trinity Amps has great customer service even after the sale is made.

Thanks:

_________________
ROB

I still am not getting the guitar to sound thru the amp, but I can hear clicks when I test the voltage at the pin sockets. One of the Speaker Jacks might be the problem why I was not hearing anything at all, but I can deal with that later.

I went thru the Pin Voltage Chart and got 3 places that were way off.

1) V4, Pin 9 - Chart Says 340 volts - I got 0 (This is the heater wire, is 340 the correct value?)

2) V4, Pin 7 - Chart Says 64.4 volts - I got 33.

3) V3, Pin 3 - Chart Says 71 volts - I got 1/2 a volt.

I have not tried replacing any tubes yet.

Thanks for any help:

_________________
ROB

#1 That is a heater connection alright. So it should probably read 1/2 of 6.3vac (3.15vac) if you're reading it with respect to ground. No idea of the 340 you quote?
#2 and 3. Untill you get the heaters sorted out for V4 then other readings for V4 and probably V3 won't jive either.
Are you getting 6.3 vac when measured between pins 2&7 on the ouput tubes?? If so then follow those filament wire over to pins 9,4,5 of V4. Pin 9 should get one of the wires and pins 4&5 should get the other. Coco's colored diagram shows which goes where.
Stew

I got the 340 volt number from the Voltage Chart - I didn't think it was right because it was about 3 volts before the tubes were installed. I got 0 volts on the 600 volt scale of the meter.

The heater wires are good.

So the V4 - Pin 7 (50% of chart voltage) & V3 - Pin 3 (1/2% of chart voltage) are the issues.

Thanks:

_________________
ROB

well that's the thing. With zero volts on the heater pin the filament isn't going to "heat up" so the tube isn't going to function and draw current which affects the voltage across the resistors etc ect. you need 6.3 volts across pins 5&9 and 4&9 of V4( 4 and 5 are connected together) this is ac voltage. btw.
Stew

The 340 volt number from the Voltage Chart is a typo. It shold be the heater voltage 6.3 V AC between pins 4-5 & pin 9 or half that amount from pins to ground.

On v3 pin 3, the 560K resistor must be connected to ground. Confirm.

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

On the layout drawing V3-Pin3 looks like it attaches to the 100K resistor, with V4-Pin2. (There is a 22uf Cap blocking the wires.)

Could I have crossed the V3-Pin2 with V3-Pin3?

Does the V3-Pin 3 go the the 560K & V3-Pin 2 go to the 100K with V4-Pin 2?

Thanks:

_________________
ROB

Schematic says V3 Pin2 goes to the 560K resistor & V3 Pin3 goes to the 100k resistor with V4 Pin2.

I will check those for open circuits tonight anyway and if they look good I will try a different tube in V3.

Thanks:

Rob

_________________
ROB

Do you have the heaters sorted out?

I will look at V3 (connections and the tube itself tonight.)

_________________
ROB

All tube voltages are OK but still no Guitar?

I think the problem is between the preamp volumes, & the tone stack.

Master Volume will increase noise, and the Bass will change the sound of the noise, the Preamp Volumes seem to have no effect.

_________________
ROB

Any chance you've miswired the OD relay/switch?
Stew

I checked before, but I will check again.

Thanks:

_________________
ROB

Turn vol down to 2 , Turn master vol down to 2, everything ad mid then carefully touch the grids of the preamp tubes and see if you get a pop. Start from the output tubes & work backwards

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

And I will double check the Guitar cord, also! It seems to be my best cord, but it can't hurt. The input jacks, too. 80% of amp problems I have in the past seemed to be jack issues.

As for the Voltage Problems, it might have been V3 pin's 2 & 3 somehow contacting each other - Probably the meter probe while I was taking readings. I adjusted the Cap that was between pin 2 and pin 6 to get the probe in easier, and the voltages were correct after that.

_________________
ROB

+1!
I'd use a meter lead for this like if you were measuring the voltage on the grid. BTW that's pin 2 and 7 on the ax7s and at7s
Stew

I do not have my amp at work, so I can't be sure, but are #1 & #2 hookups on the Bass Pot linked together? Not 100% certain, but I don't think I did that.

It's pretty hard to see that little blue line at 11:30 pm.

I will see if that's it tonight!

Thanks:

_________________
ROB

You might compare your build to Malcolm's Buid Thread. Pics in there areexcellent. Pins #1 & #2 on the Bass Pot are not linked together.

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

When in doubt I always refer back to the schematic.

Yes, even I manage to confuse myself some times...

_________________
Great tones come in small glass jars!