Blowing Fuses and Tubes, I need advise.

[MarkyKobane]

Hey Gang,
I figured I would ask here before anywhere else. I am new to having a real tube amp, so I hope my question isn't too obvious. I have a Jet City 100hdm. I recently changed the preamp tubes to these new tubes called "Retro Valves" They look pretty cool because they light up and are technically solid state so I know they are not the problem.

My power tubes however.....I changed them to a matched quad of Tung Sols. I was blowing fuses instantly after only a few months of having them in. I now know about fast/slow blow fuses. It turns out one of he tubes ALREADY burnt out?

Is this an error in biasing from the tech @ my local shop? I am trying to get another tube for free out of them, and thinking of going somewhere else for installation.

I paid way to much for this thing to be having problems this early. I was really bummed, because Jet City, even though only a few years old, has a great reputation and is made by Soldano.

[Mr. Bill]

Blown fuses can be caused by lots of things. If it is a bad tube you definitely should talk to the people that sold and installed them for you. New tubes should be covered by some sort of guarantee. See if you are still covered.

A bad tube could be caused by any number of reasons. Mis-biasing is a possible cause, but so is a manufacturing defect, mis-handling, mis-use, a problem with the amp circuitry, etc.

Talk to the shop that did the work and see what they will do for you. It would be good business practice for them to try and make you happy. If it is their product or installation that caused the issue, then they should assume some responsibility, but if it isn't their fault, then accept the fact that they may not be willing or able to help you.

[Greg_L]

I'm no amp tech....but I shock myself from time to time with them. First thing I'd do is pull the chassis and do a basic visual inspection looking for burned wires or tube sockets. If you see some burn, send it to an actual tech. Don't mess with that stuff yourself. Second thing I'd do is put actual pre-amp tubes back in it and get rid of the retro things. Pre amp tubes are cheap, last darn near forever, and rarely fail, so I see no reason to replace them with fake tubes. The amp is designed to run vacuum tubes, not SS tube simulators. Then, do all 4 power tubes light up? Does one shine more brightly than the others?

[MarkyKobane]

Thanks guys, right now the stock tubes are back in and amp is working, but I am just bummed I need to wait to put the Tung -Sols back in. The retro valves didn't really change the tone, and look great. I will post a pic soon. Thanks again.

[MarkyKobane]

[mark1]

Does the amp have a tube rectifier or a solid state? If it is a tube, change it out to a known good tube.A bad rec tube will cause fuses to blow. There are more options that would also cause this.

[Greg_L]

Haha, I like where you have the knobs set.

[Mr. Bill]

Cool look, especially with the clear plexi front panel!

I don't think that the knobs are set full up, I think that it's just a reflection on the front of the knobs.

I have not heard the Retro Valves yet, how do they sound? A lot of the distortion on your amp is created in the preamp section, so the Retro Valves will have a big influence on the character of the distortion. Do they sound like as good set of tubes, or do they sound more like a good Tube Screamer?

[MarkyKobane]

The retro valves are built by jet city, so I don't think it would be the problem. They have a few patents on them, and until new power tubes no problems.

I really think I just got a lemon of a tube, just my luck.

Yes, the knobs are a reflection. This thing has so much balls, I have my gain on 4 a never had the volume above 3.5.

I have white chicken head knobs now too.

I know the 1st preamp tube changes tone. These really didn't make that big of a difference. I was feed backing a lot ( and not a cool feedback, more of a whistle). They did seem to help with that. This is why I chose blue over red too.

There is a good YouTube video on these with some demonstrations in tone change. Nothing a pickup, pedal, or turn of a knob can't do.

Stay cool guys!

[vibramutant1965]

Get more fuses, remove the power tubes and see if it blows, if not get another quad. If so, you need to unhook the trans ,turn it on, if it blows, get a trans, if not , replace the rectifier, and filter caps, do not buy chinese filter caps........