Traynor YBA-1 issues

[Coreynewdisease]

Hi new to posting here. I have a 1971 Traynor YBA-1 Bass Master 45 watt head. I recently put new power tubes in it which are Svetlana Soft/Red EL34s in replacement to the Groove tube medium EL34s that were in it two weeks ago. The amp sounded amazing and I had no issues with it until last week at rehearsal it blew the main safety fuse that is in the back which is a 3amp glass fuse while I was playing. I got a few from the hardware store today. I put a new one in, turned the amp on and before I even took it off standby it was humming real bad. When I flipped the standby switch it blew the fuse immediately. I tried another fuse it did the same thing. I checked the power tubes and the preamp tubes. All are in fine shape. I dont know what is causing this. Any suggestions? I'm very stumped.

[Firestorm]

Sounds like a bias issue.

[Coreynewdisease]

I looked it up and it said Traynors have a fixed bias that doesn't require adjusting. I'm not sure though. I really have no idea.

[eddie25]

Pull the power tubes from the amp and put a new fuse in. Turn the amp on.

If it doesn't blow then you probably have a bad power tube.

That's a start.

Also, strangely enough fixed bias normally means that it does have an adjustment.

[LOUDthud]

I put a new one in, turned the amp on and before I even took it off standby it was humming real bad.

Please explain. Was it humming through the speaker or was the amp itself humming? Either way, there is something wrong inside the amp. Unless you have training as an electronic technician, take the amp somewhere for repair.

[Coreynewdisease]

This is exactly what it is doing as of right now. Took a video.

http://www.youtube.com/watch?v=CkVXdTrw ... e=youtu.be

[Coreynewdisease]

I put a new one in, turned the amp on and before I even took it off standby it was humming real bad.

Please explain. Was it humming through the speaker or was the amp itself humming? Either way, there is something wrong inside the amp. Unless you have training as an electronic technician, take the amp somewhere for repair.

It was humming through the speaker but without the speaker connected it was buzzing by itself also. In the video I posted it is connected to a speaker.

[Guus]

Hi Coreynewdisease,

The sound on the video tells a lot.
Like Firestorm replyed: sounds like a bias problem.

You mentioned: "Traynors have a fixed bias that doesn't require adjusting".

This is fault information in my perception.
Rebiasing with 'fixed bias technique' is only not required when the new tubes have the same Ip - Gm numbers as the old tubes or are close by.
Mostly the new tubes will have different Ip - Gm numbers and the bias has to be checked and adjusted.

Amp's that don't require a bias adjust are tube amps which uses Cathode bias technique.
I prefer always a bias check when swapping powertubes.

So take your amp to a tubeamp tech for a check.
Success.

regards
Guss.