First Build – no sound / high voltages

[red_fever]

Hi Guys,
Received my kit and started my build a few days ago.
Thought all was okay until I fired it up.

I used a Gerald weber light bulb limiter and it showed no shorts.

I get a quiet hum but nothing else.

I have a mojo760ex pt and I have used the black & black/red cables for 240v as I am in Australia.

Tested with El34 in and 5y3s and 12ax7 as supplied with kit (also tried the 6v6).
I don’t have another rectifier tube but I will pull out a known working 6v6 and 12ax7 from my rebel 20 tomorrow.

Rectifier pin 4 & 6 330v. I am having trouble getting a consistent reading at Pin 2 & 8 it seems to show at 0.365 then drops to nothing.

V2. Pin 3 448v. Pin 4 424v. Pin 5 & 6 350v. Note if scratching pin 3 when taking a reading sound (squeaky) is heard through the speakers. I think that is a good thing! Pin 8 409v

V1. Pin 6. 181v. Pin 1. 180v

3.2v at filaments

Not sure if relevant but using a Hammond 125ese with yellow and green cables.

Any suggestions would be great, I am a complete novice. Will swap 12ax7 tomorrow as its almost midnight over here.

Cheers

Dave
Brisbane Australia

[Robin]

Hi Dave,
Double check all the grounds and all the solder joints. Confirm that your speaker connection is good. Check the continuities through the circuit. Post a few photos if possible. The very slight hum is from the transformer and is normal.

[Robin]

I’m not sure what building instructions Andy is shipping with the TAN Two Stroke kit, but if you are going by the original illustration in the DH book, be sure to check that the input jack is wired correctly and that it’s not wired to ground.

[red_fever]

Thanks for the advice Robin, it was a major grounding issue!

In the book DH says to check and triple check everything, I thought that only applied to everyone else, not me!

I left off the connection from junction of 5w / 220k to ground.

Anyone know a cure for stupidity?

Fired it up with EL34 …. So so then plugged in the 6v6 and I haven’t stopped smiling.

I think there is a lot I can do to clean up lead dress etc but will play around this weekend although the hum is not too bad.

My rebel 20 has just reached retirement age!

Andy sent me one of your cabs, my next challenge will be to build one from scratch (freight to Aust is a killer). It arrived in Australia with a small dent in the top near the handle but I am putting this down to character given how far it has travelled.

Overall I am a happy camper.

Thanks

Dave
Brisbane Australia

[Robin]

Congratulations. It really is a great little amp. My favorite is a good 6L6, but today we were playing the new Two Stoke head with a JJ E34L and it sounded outstanding.
Good luck
Robin

[Author]

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