Tube Testing

[ez_willis]

My neighbor gave me an old Fender Studio amp, but it ain't working. It has 6 Groove Tubes GT-6L6GC's in it that I need to test so I can put them on Ebay or the Free Ads Forum. I am an electrotard so talk to me like an infant, baby-steps, friends.

I'm going to post a pic of the bottom of tube and post a pic of the multimeter I'm gonna test them with. I need someone to walk me through this so I do it right.

Here's a pic of the tube.

 

[ez_willis]

Here's a pic of the multimeter. I need to know where to plug the red and black cables in, where to set the dial, and which pins on the tube to test.

 

[ez_willis]

I won't be offended if you guys point and laugh at me or call be dummy.

 

[ez_willis]

I'll show you my tits!

 

[Outlaws]

That isn't how you test tubes.

http://www.tone-lizard.com/Tube_Testers.html

 

[ez_willis]

That isn't how you test tubes.

http://www.tone-lizard.com/Tube_Testers.html

I am not showing you my tits for that!

That is way more info about antique tube testers than I needed, but you have shown me the light.

For the record, I didn't buy the multimeter to test these tubes so I'm not a complete douche, well at least not for that reason.

I work at a University with a pretty serious Electronics engineering department, I'll take them in and have the department tech test them.

Thanks dude!

 

[cellardweller]

Oh,
You WILL show him your tits.
Don't gimp out on a deal now, we will lose all respect for you...

 

[ez_willis]

I'll compromise with a wet t shirt pic-

 

[Light]

You can't test your tubes with a multi-meter. It really requires a good tube tester, and unfortunatly, there is no such thing. The old tube testers can give you some valid information, but they have one big flaw. They don't test tubes at full voltage.


Basically, the only way to really tell if a tube is working is to put it into an amp you know is good, and see if it sounds the way it should.


Oh, and I have no need to see your tits.



Light

"Cowards can never be moral."
M.K. Gandhi

 

[ez_willis]

Basically, the only way to really tell if a tube is working is to put it into an amp you know is good, and see if it sounds the way it should.

I have a feeling this thread is about to get ugly. Here's why-

The amp I pulled the tubes out of was a Fender Studio, like I said. The speaker was shot, half of it was missing. There is what appears to be a little water damage. I disconnected the internal speaker and plugged the amp into a little Ampeg I have. I was getting sound but it was faint and crackly.

I wanted to see if there was any obvious damage to the amp before I threw it away, maybe something simple. If it is something simple I can replace the speaker and be good.

I pulled the amp out of the cabinet.

I've read enough to know that parts of the amp have the potential to fuck me up pretty good so I haven't done anything other than take it out of the cabinet.

Can I test the amp to see if it's worth not trashing?

It's this kind of amp-

 

[ez_willis]

Here is the inside of the amp part of the cabinet-

 

[ez_willis]

Here is the bottom-

 

[Henry Mars]

The only reliable way to test tubes is in circuit. Years ago I used to work on radio equipment .... tubes test normal on a tester and break down in circuit. Usually changing tube capacitance is not critical in audio circuits to the point where the circuit fails.
Did you check to see in the filiments are lighted?

 

[JCH]

(in my best Boris Karloff voice) Bring it to my laboratory. I can make it speak.

Don't trash it. People like me will pay good money for it the way it is.

The worse thing that could be wrong with it is a bad power supply, and still that's not a catastrophe.

I don't fix amps professionally, but I've repaired plenty for myself, and friends. If you want to throw that one away. Throw it at me.

I paid 20 bucks for this tube tester. It's nuthin' fancy, but it serves it's purpose.

 

[c7sus]

Use that multimeter to check the fuse.

That's where I would start.

 

[Thatupstateguy]

Good call C7,...... I was going to suggest that myself...



If an amp just quits all of a sudden,..... thats the first place to look.... but it usually blows for a reason,.....


for example,... be sure to check the bottom of your new tubes to be certain the guide pin in the center is there,.....



if not,... the tube could be inserted wrong,.. and blow a fuse as soon as the amp is turned on...


there are many other reasons a fuse blows,.. but as C7 said,... I would start there....



tubes rarely go bad all at once,..... and with that many power tubes,.. it is either a fuse,.. or as someone else suggested,.. it could be the output transformer,... or ,.... there are many other choices,.....

that particular amp is not one of Fenders best,... it would fall in the 'Average' catagory as far as tone,... but there are some tweaks I'm sure,....


If'n you get it workin,... try it first,... and if the tone is not right,... first choice would be to mod, or somehow change the preamp sound, where it all starts,....


anyway,... good luck with it man,..... and just one comment,.......






something like that for free..........












SCORE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!




Steve

 

[ez_willis]

It's powering up. The light on the amp is lit and the tubes were glowing.

Like I said, I plugged it into an external speaker and I was getting sound but it was faint and crackly. The external speaker may be fucked up, too, though.

My two Ampeg cabinets are with a friend(for about two years now) and I don't have any other speakers to check it with.

 

[ez_willis]

I'm thinking maybe I should just buy a 15" speaker and throw it in there.
Here's a pic of the back, split in half. Do I need a 200 watt 8 ohm speaker?

 

[ez_willis]

What if I get two 12" 's, will it be 100 watts 16 ohms each?

 

[Dogman]

Can I see your Chia Fudd ez?