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Hello Trampers,

I finished soldering everything up and was going through my pass of measurements. I was feeling rather chuffed with myself as all my voltage readings were almost bang on to the ones in the manual until I got to the LAST one (why is it always that way?).

First off though is a question: When the manual says to measure voltage at pin 6 with the Gain on and off does it mean with the Gain level all the way down and then with the gain level all the way up OR with the gain set to tweed first and then with the gain set to tude?

My measurements assumed the second, measuring first in tweed and then in tude.

My Pin 6 voltage reading are WAY off:
Gain in tweed: 325
Gain in tude: 188

However these reading are very much an average as the voltage is fluctuating rapidly up and down within a 10 volt range (roughly).

In addition, I did a very quick test with a sound source plugged in and nothing at all was coming through.

I will go back and check my wiring again of course but any thoughts that could focus my search would be welcomed.

Cheers,
Greg

gain off as you described I.e. Pull switch in/out.
1. Check ground on that cathode.
2. Try a different tube if you have one.

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

Thanks for the reply Stephan.

1. How to go about that? Cathode for that is pin 8?

Yes, check all the circuitry around pin 8. Check the Solder joints too.

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

I am waiting on a tube to swap out to check.

Wiring at the cathode appears to be fine. Did a reflow of the cathode connection.

I checked the voltage at the cathode. The diagram states that it should be 1.7 VDC but mine is fluctuating between 4.5 and 5 VDC.

Okay, so the V1 pin6 pin8 voltage problem has improved. I hadn't soldered in one side of the jumper between the 2 2K7 resistors.
Pin 6 voltage measurements are now: 175 Gain off and 134 Gain off.
These now seem low but I am not sure of how much tolerance there is in these figures.

Went to back to re-measure everything and noticed that when measuring DC to the second 50uf cap the voltage goes down instead of up when turning up the power pot (from 440 down to 410)

Also, still no sound at all (crackle/hum/anything).

Okay, read some other threads trying to hunt down the issue with the audio path.

With controls dialled up I probed pin7 of V1 and got a crackle, however when I probed on the far side of the 330K resistor connected to V1 I didn't get anything (no crackle). Should I be getting a crackle there?

Alright, tracked down the source of my audio signal problems. I have never worked with shielded wire before so I completely misread the wiring diagram. Where there was 2 black lines connected to input and power I read as being the core connected at 2 different points. Of course, it says 'shield' right on the diagram but I was just reading that as a reiteration that the cable was shielded. This wiring meant I was sending my audio signal to ground at the input. It finally dawned on me that the cable gets split in 2 with the core going to the audio circuit and the shield going to ground (which, of course, makes a whole lot more sense).

I am getting sound now! I can't fully test it out at the moment but will give it a go later.

Thanks for the update. Glad its working out!

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