Before working on olde Fender amp...

[Guitarist]

I'ave a friend who has a 196*? amp which isn't working. I'm wondering if it happens to be filter caps for example how stock should I stay? It could be DC blocking caps, swap in something the same? Stay with carbon comp plate resistors?

thanks, Guitarist

[Justin Thomas]

First, THREE-WIRE POWER CORD!!!

What model amp?

I say use middle-of-the-road caps... I like the F&Ts just cuz they look classy in an old Fender. I'll use Sprague Atoms for the cathode bypass caps, cuz they're good-looking and not heinously priced like the big ones. As far as capacitance values, go as close as is commonly available, without going down on the voltage rating. If you can go up a bit on the BIAS caps, go for it; most of those were under-spec anyway. I like the Mallory 150 600V caps, cuz they fit nice in the Fender eyelet boards AND they're a lot smaller than Sprague Orange Drops. Resistors, I use mostly carbon film cuz it's what I got. In the power supply, I use 3Watters, cuz they fit.

Is this a collector, or a player? There's a good chance a lot has already been changed out already. The most important thing is (IMHO) except for electrolytic caps, VERIFY THAT A PART IS BAD BEFORE REPLACING IT! Sorry, yes, I was yelling. I also have had zero problem with the CE Dist. (AES) can caps, if it's a Champ/Princeton/smaller amp. I prefer to not kludge newer parts inside the chassis, especially since he ground scheme in these already proves to work well with the cans, anyway.

This is all my opinion, others may differ.

Justin

[Guitarist]

Thanks Justin, I have some multi-cap cans from CEDist here already. These should work with the tube rectifier as the values aren't massive. I haven't looked at the amp yet, but soon...

[Justin Thomas]

Oh, I wouldn't worry too much about the whole max cap value/rectifier thingy... how many of these have been plugging along for years without trouble and eating recto tubes? I bet anything at 40uF is juuuuuust fine.

Justin

[Richard]

I have a 40-20-20-20 CE cap in my princeton that's been working for years.

[Justin Thomas]

And I havethe original Mallory from 1980 in my Champ. It's had the same 5Y3 for at least 6 years... I forget when I bought it! The EH 6V6s on the other hand...

Justin

[Chuck H]

What Justin said ^^^^^^^^^^^^^^^^^^^^^^^

If the amp is a player it should be made safe and eminently functional and reliable. On the off chance that the amp is completely stock you can always save the original parts (having removed them carefully, which I never do) so that if anyone in the future wants the amp to sit in a glass box as "original" (if not functional) it can be returned to it's former (not functioning) glory.

Carbon comp resistors aren't usually the noisy a$$h0!es everyone insists they are, but they CAN be. Also, they are more likely to drift off spec. The plate resistor on the input triode stages is the most sensitive one and really the only one worth being concerned with unless any other are already making crackling noises. But I would replace the input triode plate resistors with anything but carbon comp and, as mentioned, save the original for posterity.

Same for any leaky DC blocking caps. I'm in the camp that believes there can be a small difference in tone between different dielectrics, but that's the end of it. There's no magic an any of the specialty audio products or NOS caps. If you need to replace a cap just use any quality polyester cap you can get cheaper than specialty or NOS. I used the Panasonic caps in my last build because the Orange drops I was using have become stupid expensive. No complaints.

It's super important, so I'll reiterate, DO replace the bias supply filter caps (if applicable). IMHE they are nearly always original, even if the other power supply filters and film caps have been replaced. Yet they are far more important for amp safety than all the others.

[Enzo]

On the other hand, if the amp is working and you like the tone, replacing all the old caps will most likely change the sound, not always to your liking.

[Jazz P Bass]

Ahhh.

Crappy old, high ESR capacitors.

The 'Brown' sound.

[copperheadroads]

The old khaki Mallory firecracker filter caps of the 70's found in the old Traynor YBA's even though are replaced still read with in it's original spec's & tolerances .still doing its duty after 40 years .