A quick multiple option 1 question quiz re: your approach

[tribi9]

What's your approach when it comes to handling other peoples vintage amps.

A) Replace only as needed to keep as much of the mojo possible?

B) Go apeshit and swap carbon comps, old worn out pots, electrolytic caps etc to give somebody an amp that won't have any issues for at least 10 years?

C) Leave the option up to the owner?

D) Both A and C

E) Play "We built this city" while testing the amp.

Anyway, what's your approach?

[Blackburn]

You would need to provide a ten-foot-pole for me to tinker with anyone else'e vintage amp...

On the other hand, if it ain't me, I'd just replace what's needed. Occasionally people complain that their tech replaced stuff other than what they thought was needed. You should ask the owner first and with the go ahead make necessary improvements as needed and when all's done play We Built This City.

[chief mushroom cloud]

D.
I have customers that vary on their views of voodoo, ooga booga, and what adds value to a vintage amp.
I don't argue with them either. They're generally stupid anyway. Good players. Just stupid.

[pdf64]

I can't see that it's possible to warranty an amp that got carbon comps and electrolytics in their 4th or 5th decade.
If the end result is to be a giggable amp, they have to be replaced.
Otherwise I'll need paying every time it's brought back with a new problem that needs chasing down.
Pete

[JazzGuitarGimp]

I lock the client in a room and play we build this city for them at 125dB for the time it takes me to make the repairs. I go ape shit and do whatever I want with their amp. I find when I open the door and let the client out, they tend to just pay me whatever I tell to them pay without asking any questions.

[chief mushroom cloud]

I lock the client in a room and play we build this city for them at 125dB for the time it takes me to make the repairs. I go ape shit and do whatever I want with their amp. I find when I open the door and let the client out, they tend to just pay me whatever I tell to them pay without asking any questions.

I DEFINITELY have to try this

[Firestorm]

My rule is I get to do whatever I think is best. That said, what I think is best tends to be obsessively conservative. I replace all the electrolytics, but I do put the new ones inside the old cardboard sleeves (even the bypass caps). I replace CCs only if they are noisy. Same rule for coupling caps; replace them only only if they leak too much (like most Astrons, unfortunately), using 6Ps or M150s. I don't like to replace pots; if I have to, I'll dismantle them and bend the wiper so it contacts a new "stripe" of the carbon track. With basket case pots, I have occasionally replaced the carbon track wafer, but kept everything else. Everything has to be reversible (no new eyelets, etc.). And, of course, the client gets everything back.

[VacuumVoodoo]

I don't do "museum quality" restorations. For that I would have to read aloud suitable passages from the Book of Dead.
I do vintage upgrades to a better technical condition then what it was when it left the factory. Just did a 1971 JMP Tremolo. Replaced the tag board as the original had swatches of carbonized areas. Rewired and rerouted grounding, no more hum. Corrected the tremolo to give 2Hz to 12Hz modulation range. It's still the "fake echo" and stutter like it should be. Rewired mains and HV cabling to current safety norms. Kept original signal caps i.e. only the ones that were healthy. Carbon resistors went out. Renovated original pots. Did I mention new filter caps? Owner gladly paid my price. "It sounds now like it was meant to sound".
He also asked me to put a sticker with my name and date on the chassis. Nice.
You want a "nothing replaced" restoration? Sorry, I'm not a miracle business.

[jelle]

What Pete and Aleksander said. I present the owner the option. Guaranteed or as original as possible.

[Structo]

I discuss what needs to be done to the amp with the owner.

If it doesn't work, then troubleshooting follows.

I few times when presented with an amp that doesn't even pass audio, I first have to get it to work then consider options for better reliability.

It really depends on how knowledgeable the client is about amps.
Do the safety upgrades, electrolytics if needed, clip death cap, etc.

I for sure wouldn't rip out all the caps and replace them with orange drops, unless he insisted.

[BTF]

I replace only what is needed. Musicians can be a discerning lot to the point of neurosis. Early on I learned my lesson after having switched some old cathode bypass caps in a vintage Twin (following factory instructions and thinking I was doing the fellow a favor). Two minutes after he powered up the guy tells me the amp is completely different and to put it back.

[pdf64]

Hope you saved the old parts somewhere safe!
Yes, I guess most techs have been there; it's a good precaution to save all parts, but how to identify which 25uF/25V cap came off which cathode, or which 100k came from which plate?
I guess the best we can do is explain that the tone may change, before we start.
Generally their faces light up when they hear their amp brought back to life and vitality, but it's easy to feel crushed when the odd one is incensed that it doesn't sound like it did 'just before it failed' and insist you put it all back, except for the part that completely failed. OK, that 100k is more like 1M, that coupling cap is leaking dc etc, what do you want me to do?
Pete

[gingertube]

I do a lot of restorations of tube guitar and HiFi Amps.
Mostly I do D) as many of the guys above have said - except for electrolytic caps, they get changed, every single one of them, high voltage B+ supply and cathode bypass alike. If the existing electrolytics are really old then, Yes, that will change the sound, it will improve it out of sight.
Cheers,
Ian

[Kinkless Tetrode 66]

Mostly D.