Tube amp not powered on since long time

[zamproject]

Hi all

Short question for tube expert guys around.

I have my 5 tube amp:
70' Marshall 2068 artisté
80' Marshall 2550 silver jubilee
70' Fender studio bass
70' Hohner PA/keyboard
90' Peavey classic 30

For some reason (studio relocation, etc...) I don't power on any on them in the last 12month, even more for some.
I'm never confident with old tube amp, is there any precaution I can take to minimise big capacitor failure or any other think that don't like the inrush as they don't see any electron since long...
I have in mind to use my autotransformer to slowly ramp the main. Is that a good idea ? If yes, how ? add 25% each 5 minutes?
IIRC the only one with tube rectifier is the Hohner, if that make sens/difference here

Best
Zam

 

[zamproject]

OK finally find the info with right words search  :-X

Autotransfo is fine, I will monitor current with my multimeter and see what happen  8)

Best
Zam

 

[andyfromdenver]

I like to bring new builds up slow on a Variac. I don't think you need to go through extensive measurements and etc, unless you just have free time.
Make sure all the tubes are seated snuggly, and work out the crud in the pots, and bring them up over about 30 sec-1 min with a variac.
look (@ the pwr tubes) and listen

Have you recapped these amps?  They all sound due, even though they may work fine, which I know you know  ;D

take care!
andy

 

[zamproject]

Hello Andy

Thanks for your input, I will power on and check them all this week.
I already pull off the two marshall and the fender this afternoon, cleaning, check tubes connection, and global visual check.
None of them are recaped  :
The studio bass have a dead tube (white, lost vacuum, I already know) I will run it with a quartet in place of sextet.

Best
Zam

 

[andyfromdenver]

nice collection!  you've got your work cut out for you for the next 3-4 projects, money-wise  ;D
I've never seen or heard of the Studio Bass, what a cool beast.
http://ampwares.com/amplifiers/fender-studio-bass/
They could have called it the Big Stage Bass, that's a lot o' power, if matched to a big loud cab.

With two of the power tubes pulled, it is a good idea, as you stated, to take some measurements, when you fire it up. They already operate with a high B+.  I always like to know what the heaters are for starters, as an indication of wall voltage circumstance and in your case, a lower than spec'd current draw.

 

[zamproject]

yep that's my collection... since 15+ years, I never buy new tube amp since and will keep this ring as long as possible

the late 60' Hohner "orgaphone" is nice too, great tremolo, got it with two 6x10' cab and a small leslie
The classic 30 is far better since I put a true vintage green back, it's a noisy amp but practical small combo.
There is nothing more to say about the 2550, absolute great amp, I'm happy to have one
the 2068 "artisté" is an uncommon marshall, not well loved IIRC, I like it, strangely clean with a reverb in it !
Studio bass is a beast as you say... I have a head cutted version, coupled with a 4x10" carvin bass

Anyway, I already power on the 2550, everything is fine except scratchy pot and the usual dusty send/return loop jack that cause intermittent cut.

Unfortunately my only meter (DMM) seem dead in AC amperage fuction, fuse is ok so...

I can't monitor current wile turning the autotransfo knob :-X
So as you say, I turn slow, watch and listen

Now time to power the Artisté 100W

Best
Zam

 

[zamproject]

Artisté done
Noisy main trafo (which was already the case before), ear the 100hz in the room, maybe I can check rectifier
Random small scratch and noise, for sure need a recap...Factory label say: TEST 4-1-74 (hand writed)
that's a long way for HT caps

Now the Studio bass, but I have a problem, my variac is rated for 2A 
510W main input label... should be around 2.7A if my math are good
Let say it will be ok with 4 tube in place of 6 ?

Best
Zam

 

[zamproject]

Hey

Fender studio bass OK, no major issue

The Hohner work too, despite some caps show inflation, need a recap...
the exact name is "orgaphon super reverb 76"
I just check the tube inside...all telefunken
6xECC808
1xECC83
1xECL86
duet EL503
I think I will never retube this one, price is prohibitive for those tubes  :-\

Best
Zam