Power Tubes in whh socket?

[rambo123]

Hi, I realise this is a stupid question, I'm no tech so here it goes. I have a 1973 marshall superlead ptp I took out the power tubes but I can't remember the order of the 1st and 2nd (i mixed them up). The power tubes I have are svetlana winged c el34s. So my question is how do I know which power tube goes into which socket of the amp. Anything on the power tube that would distinguish it? Any help would be appreciated, thanks.

I just recently bought the amp from somebody else, the power tubes came with it.

Also any suggestions on the replacement of the main fuse? What size and specs would I need for 1973 superlead, slow blow or quick blow etc..? Thanks!

 

[Frankie]

It might make a minute difference in the bias if you don't put them back into the same exact sockets, but not enough to matter. Just throw 'em all back in whichever way you want, amps aren't really that picky.

It should say on the back of the amp which type of fuse to use, I don't know that one off the top of my head. They're usually slo-blo types.

 

[rambo123]

thanks for the quick response.

 

[Ronnie_Speedbag]

I'm not that picky...

 

[rambo123]

Well i pulled out the blown fuse, it turns out that its a buss agc 3a 250V. When i check on ebay there are only buss agc 3 not 3a and theres lots of different types. Any ideas which one would be the same as mine? or does it really even matter?

 

[demonufo]

Okay, AGC is probably not the best substitute for a slo-blo fuse. You need to look for a T rated fuse (the T should be just before the amps on the endcaps) which stands for Time delay, also known as slo-blo or anti-surge.

Fuse rating depends on the voltage of your wall socket. For instance in the UK, we're in 240V territory so we'll need a lower rated fuse, since the amp will take what it needs from the secondary windings. In turn the primary windings will feed what it necessary. Because we're twice the voltage of US etc, the current required is halved.
4A for 240V and 2A for 120/110V in general.

 

[rambo123]

ok im kind of confused. The fuse that came wth the amp when i bought it from the dude was this buss agc 3a 250V (thats basically all thats written on the fuse). I have no clue if it is a slo-blo or fast blow, how would I know? What company would you recommend that I use for this amp? I heard that your basically not supposed to switch slo blow with fast blow or it will cause problems, so i'd like to be sure what kind of fuse the amp was running (Idon't see any T on either ends of the fuse).

 

[Frankie]

According to this 1959 skeematic from 1970 it shows a 4A fuse for the mains and a 1A fuse for the OT.

 

[demonufo]

Yep. That's for US voltages. (Unicord was the US distributor for Marshall)

 

[demonufo]

ok im kind of confused. The fuse that came wth the amp when i bought it from the dude was this buss agc 3a 250V (thats basically all thats written on the fuse). I have no clue if it is a slo-blo or fast blow, how would I know? What company would you recommend that I use for this amp? I heard that your basically not supposed to switch slo blow with fast blow or it will cause problems, so i'd like to be sure what kind of fuse the amp was running (Idon't see any T on either ends of the fuse).

AGC are a quick blow type. Get some proper fuses in there. Both types should be slow blow. 1A for the HT fuse in a 1959 (500mA for 50W amps) and in the mains fuse, 4A for 100/110/120V mains/wall voltage or 2A for 200/220/230/240V

 

[Frankie]

Listen to Mr. UFO, he knows his shit.

 

[demonufo]

An awful lot of complete SHIT is exactly what I do know.


Just not from under a glass coffee table.
Darn, where's a blowing chunks emoticon when you need one.





(Now if only I knew something truly useful...like how to make decent money)

 

[Ken]

Since you bought the amp with a blown fuse, might I suggest you at least retube it? Old tubes can easily blow a fuse and if you're unlucky blow the OT. This is a really nice amp, and a few hundred bucks in tubes, a proper bias and maybe caps would be a good investment.

Ken

 

[rambo123]

AGC are a quick blow type. Get some proper fuses in there. Both types should be slow blow. 1A for the HT fuse in a 1959 (500mA for 50W amps) and in the mains fuse, 4A for 100/110/120V mains/wall voltage or 2A for 200/220/230/240V

And how do I know the mains/wall voltage? I'm in canada if that makes any difference?!?

 

[demonufo]

Seriously? You don't even know the mains electrical voltage in your country?
Yikes!

 

[chuckharmonjr]

Lick two fingers...stick them on two hot wires of a live circuit...one ball blows off its 120...both balls blow off its 240

















no oh hell no dont do that...I was just kidding

 

[Frankie]

Seriously? You don't even know the mains electrical voltage in your country?
Yikes!

:Ohno:

 

[Clammy]

And how do I know the mains/wall voltage? I'm in canada if that makes any difference?!?

It's 120v up here in Canuckland.

Cheers!

 

[rambo123]

Ok, the HT is 2A and the Main is 3A so I need a 1A and a 4A. Does the glass or ceramic make a difference for the fuse? Is buying them off ebay from hong kong a bad idea vs a u.s. seller? Thanks.

 

[demonufo]

Over here in the UK you don't usually find ceramic slow blo's in the correct physical size.
Don't know whether or not any ceramic's elsewhere may be correct. (I think there's usually like a 2mm difference in length, but I could be way off base here)

The correct T rated fuses are pretty much always glass from what I've seen. Later amps with those piddly little fuses are a different story though.
Personally, I'd rather stick with home territory when buying stuff like fuses. Saves any confusion.