Greetings all - I wrote Bob about this issue directly (email copied below) but wanted to reach out to the community to see if there are any folks awake with any ideas.
I have received my kit (VTA ST70 with tube rectifier, upgraded caps) and have spent the past two nights building and I'm running into an issue. I first tested the driver circuit tubes and everything checked out - tubes lit up nicely. Then I attached my speakers and attached the speakers, rectifier and left output tubes. I was able to set the bias on these tubes.
Now the problem - once I turned off the amp and added the right output tubes the rectifier tube sparked after 10 or so seconds which in turn blew a fuse. I double checked all of the quad cap connections since I've read on the blog this is likely the cause for a slow blow.
I've swapped around the output tubes and both sides are now blowing the fuse. Additionally, I no longer read a bias voltage on the left output tubes - even with the original tubes i used when I was successful.
I've double checked the wiring and I believe everything is correct. I could attach photos if needed. Please let me know what my next steps are - bad rectifier tube? Bad capacitor?
Thanks to you all - I've learned a great deal while surfing this forum.
Can't wait to hear how this amp sounds.
P.S. My line voltage is usually around 125V. Could this be the problem?
I have received my kit (VTA ST70 with tube rectifier, upgraded caps) and have spent the past two nights building and I'm running into an issue. I first tested the driver circuit tubes and everything checked out - tubes lit up nicely. Then I attached my speakers and attached the speakers, rectifier and left output tubes. I was able to set the bias on these tubes.
Now the problem - once I turned off the amp and added the right output tubes the rectifier tube sparked after 10 or so seconds which in turn blew a fuse. I double checked all of the quad cap connections since I've read on the blog this is likely the cause for a slow blow.
I've swapped around the output tubes and both sides are now blowing the fuse. Additionally, I no longer read a bias voltage on the left output tubes - even with the original tubes i used when I was successful.
I've double checked the wiring and I believe everything is correct. I could attach photos if needed. Please let me know what my next steps are - bad rectifier tube? Bad capacitor?
Thanks to you all - I've learned a great deal while surfing this forum.
Can't wait to hear how this amp sounds.
P.S. My line voltage is usually around 125V. Could this be the problem?