My silverface princeton won't turn on! what gives?

[thesweetness]

Just scored a 71 Princeon no-verb from a TGP member at an amazing price. It powered up and sang all last night. I just went to turn it on now and it powered on again, but right before the tubes heated up the jewel light fizzled out and the amp shut off. Now it won't turn on at all. I pulled out the fuse and it didn't look blown, but then again I don't really know what I'm looking for there. The chord had been replaced to a three prong but the ground prong was missing, maybe that has something to do with it.

Whats causing this and how do I fix it?

[SatelliteAmps]

If nothing is lighting up, and the fuse is still good, then there are only a few options. Bad power switch, bad electrical cord wiring, or bad transformer. You should have the three prong cord replaced correctly when you get the amp fixed.

[phsyconoodler]

It may have blown one of the 100 ohm resistors that form the virtual center tap for the filament supply.One goes poof and the light won't work and the tubes won't light up or work.

[Mike9]

Check the jewel light housing - they sometimes make funny - Fender didn't splurge on those.

[SatelliteAmps]

Usually the filament center tap going bad will pop the fuse.

[tmaker]

Check the fuse with a meter, a visual inspection is just not enough. A fuse can blow but still look OK.

[Spudman]

Mine was that the plug finally failed at the end of the power cord. Check that too.

[thesweetness]

Here's an update. Turns out the fuse was blown, but I tried putting in a new one and it instantly blew. I tried another, same results. So now the amp is clearly just blowing fuses. The amp would turn on for a split second so power IS flowing into the amp, which tells me the chord is fine for the time being.

So my next guess is that its a rectifier tube problem. The amp came with a 5u4G, and I happened to have a sovtek GZ34 laying around so I tried that coupled with a new fuse. The fuse blew again almost instantly. What's left to do here? bad transformer?

Also does anybody run the GZ34 instead of the 5u4G in theirs? I've read mixed things about doing this, including that you could seriously blow your princeton should you use a GZ34/5ar4 in amps where the tube chart specifies a 5u4G. I'd like to be able to use the expensive NOS philips mislabeled gz34/5ar4 tube that I also happen to have but I obviously don't want to harm anything.

[Blue Strat]

Try it again with the power tubes removed.

[SatelliteAmps]

And if it still pops, try it with the preamp tubes removed.

[thesweetness]

I tried it with the tubes removed, it still popped the fuse. I'm starting to think it may be a transformer.

How much would it cost to get a new transformer? And if this is the case, what should I look for? Should I look for a vintage one? What do you guys recommend for a vintage fender?

[Blue Strat]

I tried it with the tubes removed, it still popped the fuse. I'm starting to think it may be a transformer.

How much would it cost to get a new transformer? And if this is the case, what should I look for? Should I look for a vintage one? What do you guys recommend for a vintage fender?

Check the www.mojotone.com (http://www.mojotone.com) site. Whatever they sell is more than good enough, typically Heyboer.

I HIGHLY recommend having a tech do this job for you after determining if the transformer is really required. Transformers don't just go, something else causes them to go. If you just replace the transformer you'll likely repeat this exercise again and again.

[SatelliteAmps]

I would highly doubt a blown PT in a Fender without having a reason to suspect it. Blowing fuses can be other things that should be checked out first.

Could be a short, from any wire from the power transformer, or even the light housing touching the filament supply to the chassis. Could be a bad filter cap. Could even be a shorted bias supply.

Has anything ever been done to this amp, re-capping, convert to a 3 prong cord or anything like that? Also, are you using the correct 1A Slo-Blow fuse?