70's Ampeg V2: need some maintenance help

[52 Bill]

If I do it that way, don't I have to do a bit more wiring?

Yes, just like the diagram that you posted earlier. The hot (black) goes to the outer fuse and then should go through the inner fuse to the power switch and then to one side of the power transformer primary. The neutral (white) should go directly to the other side of the primary winding.

[Jonny toetags]

Thanks guys....it's been going great!
I ended up changing the tagboard while i was at it. Good thing I did: it crumbled when i removed it.
I've also been resoldering suspicious connections.

I'm going to tackle the boards now:
http://privatepollution.com/images/Ampeg/board2.jpg
http://privatepollution.com/images/Ampeg/board1.jpg

I'm going to change those 2 white .47 caps.
Should I change the little greenish blue ones (besides the 2 .33's)?
Also, I noticed some resistors were sitting really high off the board....is that normal?

How would you guys hook up the bias trim pot so it's accessible without removing the top panel? Should i go trim pot or std 16mm.

[g1]

Those 2 board pictures you posted are both the same (board 1 jpg not there).
Yes it's normal for some resistors to be raised off the board (keeps heat off board).
What is your concern with the white caps? Looks like a cosmetic issue as they both seem to have the same dark spot.

[Jonny toetags]

Those 2 board pictures you posted are both the same (board 1 jpg not there).
Yes it's normal for some resistors to be raised off the board (keeps heat off board).
What is your concern with the white caps? Looks like a cosmetic issue as they both seem to have the same dark spot.

Fixed the link.

Looking at them I'm just trying to prevent anything from failing.

[NZaudio]

I am just adding some general info to it.
Gnardos comments have been quite good, but never use a tubeamp without a load, regardless if it is a loudspeaker or a load resistor.The output tubes are only stressed if the transformer is shortened on the secondary, but if the transformer is open and you play it....it'll die.That can become very costly. I even hook up a load resistor for just static measurements.That's why some manufacturers have the outputs shortened to GND via the output jacks, just to help you not blowing up your amp, but that doesn't mean that you should test it that way...
A cathode resistor is not only current sensing, it also tells you straight away if the tube works or not, also a 10 Ohm resistor in each cathode sounds much more cleaner and lengthens the tube life. Arr, there is a small disadvantage, it will be a little bit less power in the output but I think it's well worth it.
And last not least, the golden rule number one: Always have one hand in your pocket when you measure tubeamps. For your own safety!

[Jonny toetags]

I got sidetracked with a few other projects and sat down with the V2 again.
Here's my issue:
-Power works fine (power/stdby), but when i switch the amp off standby (play mode), I get a humming/popping, that slowly gets louder and louder. This happens with the volumes at 0 and no guitar connected.
The only other mods i've done so far (besides ground plug, which is wired exactly like this) are changing are the small electrolytic caps on the circuit board and replacing the two .33's to a couple .22's (yellows in this pic)

v2board

Edit: It sounds like this: http://www.youtube.com/watch?v=-CBJSzC88Lg

Update: I just powered the amp on with no preamp tubes then slowly put them back one by one...now it seems to work fine.
I'd still like to know what could have caused that. Weird.

[Aloha_Mark]

Update: I just powered the amp on with no preamp tubes then slowly put them back one by one...now it seems to work fine.
I'd still like to know what could have caused that. Weird.

Probably dirty pins on the tube sockets. Did you dab the pins with Caig's DeOxit? Were the tubes put back into the same sockets they were removed from? The amp has two inputs, Bright and Normal, so pick the channel you use, and put the quietest 12AX7 into that socket, either V1 for Bright or V2 for normal.

Having been fooled many a time about finding the root cause of noise in a tube amp, don't be surprised if the crackling and hissing comes back. Removing and replacing a tube socket on a PC board is not a task that I envy.

[g1]

Removing and re-inserting the preamp tubes may have scraped the connections clean of oxide as mentioned by Aloha Mark.
Should the problem come back, check the solder the board mounted sockets, it is not uncommon for these V series amps to need resoldering of the sockets. In such cases wiggling the preamp tubes will sometimes offer a temporary "cure".

[Dave Curtis, dB AudioTech]

Probably dirty pins on the tube sockets. Did you dab the pins with Caig's DeOxit?

I only use Caig's ProGold on tube pins. DeOxit isn't rated for the heat...

[Jazz P Bass]

Yup.
Good call.

[Dave Curtis, dB AudioTech]

The new stuff is called DeOxit Gold so the OP was sorta correct. If the sockets/pins are cruddy, I use a non-residue contact cleaner first, then treat the tube pins with the DeOxit Gold. I'm afraid that on some tube pins regular DeOxit may turn to a semi-insulating varnish; IIRC, it's rated at 100C. I actually called Caig when ProGold changed to DeOxit Gold and asked about the temperature rating and was told that although it's lower than ProGold, it's rated at 200C and is fine for tube pins. I have a few of the pens around here, and every amp I work on gets treated.