Fuse blowing problems.

[nickm57]

Hi Guys
I know this is more about building but could I get some tech advice.
I'm a player and built this thing but I'm lacking some fundamental tech problem solving skills.

Amp is a Ceriatone Started life as a 50watt.
Since I have replaced the power transformer with a new 100watt ceriatone one. The original blew.
Output is 100 watt magnetic components. So now running as a 100 watter.

The amp has been running fine for 11 months. Probably 120 odd shows. It does not see home use.

So it's blowing the HT fuse. It was blowing this when I changed the power transformer but I upped the value to 1amp and all was fine.

Could anyone tell me a good place to start. No smoke or bunt comps. Had a good poke around for bad solder joint.
Power transformer again?
Output trans?
Bad valves ?

thanks Nick

[nickm57]

Just to add
it's blowing the fuse ht with no valves. Heaters light up with valves on stand-by.
The HT is from the center tap of the B+.

What would be the way to start checking?
disconnect the B+? I'm suspecting another power transformer......
or power supply?

[talbany]

disconnect the HV B+ w/ no tubes see if it blows then

Tony

[Structo]

Are you running four power tubes now?

In other words, did you take a 50 watt amp and convert it to 100 watts?


What are you biasing the power tubes at?

[nickm57]

thanks for the replies

Yes 4 tubes. Running 35ma a tube.I converted it over.
Tried pulling the 2 outside tubes as they were the ones with the most recent work(50-100watt). But after 6 months of being thrown around, I thought a problem would have shown up earlier. I'm careful with my work. I then pulled all the Tubes.

As soon as I can I'll disconnect the B+.

But I'm confused. As the fuse is blowing when the B+ is turned on.

So only if it's shorts in this situation the PT shot?
If not look at the power supply/rectifier ?
Should I check the voltages on the PT when is disconnected.

Also is there any way of using a multimeter check the current draw, as I'm burning a fuse every time I test.

If it is the Power trans, 12 months life on these things is just not good enough.

[nickm57]

Sorry for the panic.

All sorted just a Bad tube. I put a 500ma fuse in when testing the no tube situation. Took a deep breath and worked slowly and all was revealed.

Winged C, first major failure of these. I've been using them for 10 years.
Not sure which of the quad failed but any suggestion on different brand TAD or Tug sol are easily available here.
Thanks Nick

[Bob-I]

All sorted just a Bad tube.

99% of tube amp breakdowns are caused by tubes.

[sergio]

I recently had bad experiences with the Winged "C"

I found some shorting tubes in my matched quad. orders and it's a nasty surprise and makes you angry.

Sergio

[Structo]

In looking at the Ceriatone layouts, only the non HRM 100w amp shows a 1 amp quick acting fuse.

All the rest show a .5 or 500ma fuse.