Amp's done (Rocket) - Smoke test tomorrow

[George61]

I finished the wiring on my Rocket build. This is my second vacuum tube guitar amp build and my first build was not a winner. I tried to do the wiring very neatly this time.

I am not sure how to test the amp. First I will spend several hours quadruple checking the wiring. I have a variac. I figure I would test the amp with no tubes. First at maybe 30VAC and I could check to see if the power transformer secondary voltages were approximately 25% of what they should be. Then I could test the amp with no tubes at full voltage. Then I could put in the tubes, hook up a speaker, and see what happens.

[xtian]

Beautiful, George!

The only funky thing I see is your heater wiring. Good lead dress, according to most, suggests tightly twisting the heater wires to help cancel hum. But you can address that later if hum is an issue!

Paul Ruby has a great first-time-start-up guide: http://www.paulrubyamps.com/info.html#FirstPowerUp

[Bob S]

Looks good George - well done.
Lots of the guys use a bulb limiter for initial power up, followed by the variac.
The Rocket is a little more forgiving than the Liverpool or Express.
Good Luck for tomorrow.

[ampmike]

Nice George,Really clean and neat,Amazing job,looks like you have done a lot of amps!!!!!!Good luck tomorrow Bro!!!!!!!!!

[Reeltarded]

Rock! It looks great!

[Koop]

Very nice looking workmanship. I'm sure you'll love it.

[George61]

My amp passed and the smoke test and it doesn't make any weird noises. All of the voltages are good except for the plate voltage on V4 and V5, which is too low. On V6 and V7 the screen voltage is 287.3 and the plate voltage is 289. On V5 and V6 the screen voltage is 287.3 and the plate voltage is 283.5 - that's not right.

I did a sleazy resistance check on the output transformer. The total resistance is 329 ohms. The resistance from the center tap to V4 and V5 is 236.5 ohms and the resistance from the center tap to V6 and V7 is 92.5 ohms. That doesn't seem right. The transformer took a hell of a shot in shipping and there is a big dent in one end bell.

Help!
George

[xtian]

Did you have the tubes pulled out when you made that OT measurement?

[George61]

Did you have the tubes pulled out when you made that OT measurement

Why yes I did. Although I get the same readings with the tubes in and power off. I also swapped the sets of tubes from side to side and that doesn't make any difference.

[martin manning]

There is usually some difference in the DC resistance of the two halves of the primary, but that is too much. You could take the dented bell off and inspect the windings for damage, but I think you need a replacement.

[George61]

but I think you need a replacement

Would it be worth trying to get another Heyboer HTS-8093-1? The first one I got doesn't work, and I got it from RJ who is not doing business at the moment so I would have to try and get it directly from Heyboer.

It looks like the other choice is an A470-S from Triode USA.

Desolder on,
George

[martin manning]

Did you try a pm or direct e-mail to rj?

[George61]

No, I did not try to contact RJ. From what I gather from the message on his website, he's trying to get away from the amp business for awhile, and I did not want to bother him.

Since I am desperate, I guess I will send RJ an email to see if he has another transformer. If RJ doesn't have a Heyboer I will get the Triode.

I have over a year in gathering parts, and more importantly, researching guitar amp building in this amp. I have a really nice cabinet that was made by Larry Mann. I want to get this amp working so I have an amp to use. Then I can gut my 36 watter and try to get it working properly. This guitar amp building obsession has totally replaced my fly fishing obsession.

[Drumslinger]

Nice looking build there, George!!

[rp]

This guitar amp building obsession has totally replaced my fly fishing obsession.

I'd give a lot to have my amp building obsession turn into a fishing obsession.