1969 Princeton (N.R.), Just Electrolytic's Or Complete Re-Cap???

[Nostalgic Distortion]

So Like the title says I’ve got a 1969 non reverb Princeton that I acquired as a chassis a while back. When I got it it did work but there was a lot of crackling in the signal, which I pretty much attributed to the filter can & other electrolytic’s...

So I’ve gotten all of the electrolytic oil cans swapped out now & I’ve replaced the multi-tap filter can with a brand new CE (Mallory) 20uf/20uf/20uf/20uf can capacitor.

So at the moment it sounds absolutely great! Pretty much all of the crackling background noises are history, the low end isn’t as flubby as before, & the tremolo circuit seems stronger.

Furthermore, it seems to be running great! For the past three nights in a row I’ve played through it for at least three hours straight & it’s stayed cool, Etc....

So my question is this, should I just leave well enough alone? Or should I keep going & replace the other (roughly ten total) coupling/tone capacitors?

I already have a bunch of Blue SOZO’s & Orange Drop’s? Certainly more than enough, & all the right values, to completely re-cap it...

So I guess since I have everything that I’d need to do it here already it’s something of a temptation to do...

[Nostalgic Distortion]

I will try to get some photos up soon, my phone isn’t cooperating today for some reason?

However the capacitors in question are the old brown turd caps....

[jeremy]

if its working and sounds good, id say leave it for now and just play the thing. you can do the rest of the caps down the line when you arent having as much fun playing

[Liam1963]

I rebuilt mine (BDRI) completely once I had the "hood" opened, replaced every single resistor, cap, pot, even the input jacks, so I didn't have to perform repeat visits.

[Mincer]

I would make sure it can safely run, but unless it needs anything for operation (or it simply sounds bad), keep the parts in there until they go.

[Nostalgic Distortion]

Alright, thanks fellas....

I guess I’ll hold off on the others for now, as it is working & sounding fantastic at the moment...

[idsnowdog]

You could replace the electrolytic's and test the other caps to see if they are within tolerances. You should also visually inspect and test the resistors to see if any are breaking down or are out of tolerance.

[Ewizard]

Usually, leaking coupling caps will cause your pots to crackle and make your preamp sound like dookie as DC that leaks past changes their bias. So while it does sound right at the moment, they may be fine, but if one has gone bad, the others are not far behind. I.E. if your HT PS caps went bad, why wait till the coupling caps do too? You do not want them ( coupling caps ) to completely fail or it may take a tube with it.

The predominant cause for crackling or frying pan cooking bacon sounds is the plate resistors. I would at the very least replace all the plate resistors and you may as well replace the screen grid resistors for the power tubes while you're at it. The plate resistors failing isn't as bad unless they fail low or nearly closed ( not likely, and a rare occasion ), but a failed plate resistor will have drifted considerably from its spec and as they heat up, this will cause them to shift even more during operation. Screen grids are much more important. They are the lifeblood of your power tubes. You do not want those to ever fail or drift dramatically from their spec. Since there is only a handful of plate and screen grid resistors, you may as well get them done. I would suggest a 1-watt metal film for all those. The Princeton uses a bias shifting tremolo circuit if I am not mistaken, and I am not 100% familiar with how it develops its idle bias, but it may behoove you to change whatever resistor that is as well. I know that it uses a pot that is in the bias circuit that utilizes a capacitor to create the bias shift. Of which you may want to replace that particular capacitor as well. I guess my main point is that you should change all the crucial parts because if they fail it will either ruin your day or your amp.