Oops - So I fired up a 6G2 Princeton with no tubes in it...

slack · February 18th, 2006, 06:56 PM

I made a mistake.

I powered up a 6G2 Princeton and fumbled around for a few minutes wondering why it wasn't working before realizing that I had pulled all of the tubes out of it at some point. Something I had forgotten. I turned it off, re-installed tubes, and powered it back on. Now it's not working. Just a low hum. Fuse never blew.

Haven't pulled the chassis for a look yet, but what am I likely to have damaged? :(

Dacious · February 18th, 2006, 07:40 PM

Oh no, Slack! It'll be unrepairable! You better send it straight 'round to me, and I'll make sure diddums amp is never mistreated by nasty ol' Slack never no more!

Just kiddin'

Commonest trick in the world is fire up a chassis, no tubes or speakers. That way you can check the various voltages in the tube sockets and make sure you haven't got hundred of volts on pins where you should have nothing or very little.

No damage should have occurred. Without the tubes there, there is no circuit and precious little current drawn. Just don't make a habit of it, and we'll let you off - just this once, mind!

Sure you got all the tubes in the right slots? Speaker lead in the right hole?

The only thing that may have happened, is it may have popped an old cap. If so, it was about to let go anyhow - better with no load than when you're doing your best EVH impressions.

Why did it have tubes out - maybe it wasn't working then, either?

slack · February 18th, 2006, 07:52 PM

Quote:

Originally Posted by Dacious

Why did it have tubes out - maybe it wasn't working then, either?

I knew that would be in the first response! Logical question.

No, nothing was wrong with it. I have several 62-64 Princetons. I had pulled it's tubes to try in another amp, knowing these tubes were good. I just forgot about it.

Thanks for replying. :D

David Barnett · February 18th, 2006, 08:26 PM

With no tubes, there should be no voltage anywhere except the bias supply, so if you actually did blow something, that's where I'd look first.

milocj · February 18th, 2006, 09:12 PM

This is pretty obvious so don't get mad that I brought it up, but the rectifier tube and the 6V6s will interchange. Check that first.

slack · February 18th, 2006, 09:16 PM

Quote:

Originally Posted by milocj

This is pretty obvious so don't get mad that I brought it up, but the rectifier tube and the 6V6s will interchange. Check that first.

I haven't yet pulled the chassis, but I did go through the tubes again. Nothing in wrong sockets. Thanks though, good point.

slack · February 18th, 2006, 09:37 PM

Just pulled the chassis. Everything looks fine. No blown caps, no broken joints, etc. In fact, it all remains 1964 original and untouched. The tubes I put in it came right out of a working Princeton. This one was the best sounding of my Princetons, last time it was working (based on original amps AND speakers).

tazzboy · February 18th, 2006, 11:36 PM

well then put the tubes back in re adjust the bias to the proper settings and plug your guitar (and effects if you are using any) and give it a go.

The worset is you aren't going to get any sound out of it at all.

slack · February 19th, 2006, 12:49 AM

Quote:

Originally Posted by tazzboy

well then put the tubes back in re adjust the bias to the proper settings and plug your guitar (and effects if you are using any) and give it a go.

Bias a 6G2 Princeton?

tazzboy · February 19th, 2006, 01:16 AM

Quote:

Originally Posted by slack

Quote:

Originally Posted by tazzboy

well then put the tubes back in re adjust the bias to the proper settings and plug your guitar (and effects if you are using any) and give it a go.

Bias a 6G2 Princeton?

Well that's what I read on the Fender Amp Field Guide. Guess that is wrong

fezz parka · February 19th, 2006, 01:36 AM

Quote:

Originally Posted by slack

Quote:

Originally Posted by tazzboy

well then put the tubes back in re adjust the bias to the proper settings and plug your guitar (and effects if you are using any) and give it a go.

Bias a 6G2 Princeton?

Yep. It's a fixed bias amp.

slack · February 19th, 2006, 03:32 PM

So, today it is working again. Apparently it's toying with me, making me look silly.

I'm thinking it's a flakey tube.

David Barnett · February 19th, 2006, 06:28 PM

Quote:

Originally Posted by slack

So, today it is working again. Apparently it's toying with me, making me look silly.

I'm thinking it's a flakey tube.

Got an octal tube with the guide pin broken off?

Tremo · February 19th, 2006, 06:54 PM

Look, Slack, no offense intended, but it is pretty clear that you have no idea what you're doing. I'd suggest that you take the amp to a tech before you blow something up.

Dacious · February 19th, 2006, 08:17 PM

What it may have been, Slack, is just a little corrosion - invisible to the eye - built up on your input jack. Couple with a bit of dust, and bingo - no contact, just hum. Work the jackplug in and out a few times and all of a sudden it works again.

I think Brother Tremo is lookin' after your best interests in suggesting a tech-check. If it is all original, those filter caps will be straining, and the little electros on the board will also be a bit sad.

I've seen a 60's radio chassis which popped a cap - the stuff is like corrosive Space Invader - fills ever nook and cranny, and takes hours to pick out. If you have bad luck and the elements short inside, say goodbye to your power tranny and maybe tubes.

slack · February 20th, 2006, 04:57 AM

Quote:

Originally Posted by Tremo

Look, Slack, no offense intended, but it is pretty clear that you have no idea what you're doing. I'd suggest that you take the amp to a tech before you blow something up.

Well, I'm certainly no amp tech. This is true. And, like I said, this thread made me look silly and I knew that then and now. I'm fine with that. But, with dozens of vintage Fender amps, and having been pulling them apart when buying/selling/trading/documenting them for decades, I've yet to blow anything up. And I've even been known to solder in a few. 8)

No offense taken. Just your, um, point.

I'll ask it as I always do - feel free to recommend a fair priced, timely turnover, quality amp tech in LA. I've yet to find him/her.

Btw, turned out to be a bad power tube. It's now running fine on a pair of Sylvania/JAN 6V6GTY brown bases that silverface gave me a while back.

JohnnyCrash · February 21st, 2006, 12:38 AM

I could take a look at her.

I'm in Orange County.

It's kinda hard to mess up an old Princeton like you're saying.

I'd unplug her and check the solder joints first... then dried out caps would be the next suspect. They will look like working caps, so you can't really "eyeball" it for bad ones.

If it craps out again, or starts killing tubes/fuses, checking voltages would give you a good place to start - THAT COULD ZAP YOU GOOD, so perhaps learn more about amps, or take her to someone.

slack · February 21st, 2006, 01:13 AM

Quote:

Originally Posted by JohnnyCrash

I could take a look at her.

I'm in Orange County.

It's kinda hard to mess up an old Princeton like you're saying.

I'd unplug her and check the solder joints first... then dried out caps would be the next suspect. They will look like working caps, so you can't really "eyeball" it for bad ones.

If it craps out again, or starts killing tubes/fuses, checking voltages would give you a good place to start - THAT COULD ZAP YOU GOOD, so perhaps learn more about amps, or take her to someone.

Thanks... Do you have a shop? Bad drive for me, though.

I checked all the solder joints. Caps look good, but as you said...

It's been running good since swapping tubes. Playing through it right now.

Btw, while not an amp tech for sure, I know how to safely work in amps. I work professionally with 20,000 watt lights and 100 amp Bates connectors and 600 amp Edison breakout boxes - usually in the pouring rain, it seems.

February 18th, 2006, 06:56 PM	#1 (permalink)
slack Tele-Afflicted Join Date: Sep 2003 Location: Hollywood, CA Posts: 1,929	Oops - So I fired up a 6G2 Princeton with no tubes in it... I made a mistake. I powered up a 6G2 Princeton and fumbled around for a few minutes wondering why it wasn't working before realizing that I had pulled all of the tubes out of it at some point. Something I had forgotten. I turned it off, re-installed tubes, and powered it back on. Now it's not working. Just a low hum. Fuse never blew. Haven't pulled the chassis for a look yet, but what am I likely to have damaged? :(

February 18th, 2006, 07:40 PM	#2 (permalink)
Dacious Friend of Leo's Join Date: Mar 2003 Location: Godzone Posts: 2,612 35 Photos	Oh no, Slack! It'll be unrepairable! You better send it straight 'round to me, and I'll make sure diddums amp is never mistreated by nasty ol' Slack never no more! Just kiddin' Commonest trick in the world is fire up a chassis, no tubes or speakers. That way you can check the various voltages in the tube sockets and make sure you haven't got hundred of volts on pins where you should have nothing or very little. No damage should have occurred. Without the tubes there, there is no circuit and precious little current drawn. Just don't make a habit of it, and we'll let you off - just this once, mind! Sure you got all the tubes in the right slots? Speaker lead in the right hole? The only thing that may have happened, is it may have popped an old cap. If so, it was about to let go anyhow - better with no load than when you're doing your best EVH impressions. Why did it have tubes out - maybe it wasn't working then, either? __________________ My other Telecaster is a Thinline The Tele Bible, Ch 1, v 10 Love thy Telecaster, covet not thy neighbour's Strat!

February 18th, 2006, 11:36 PM	#8 (permalink)
tazzboy Friend of Leo's Join Date: May 2005 Location: Eugene, Oregon Age: 31 Posts: 3,151	well then put the tubes back in re adjust the bias to the proper settings and plug your guitar (and effects if you are using any) and give it a go. The worset is you aren't going to get any sound out of it at all. __________________ tazzboy

February 19th, 2006, 08:17 PM	#15 (permalink)
Dacious Friend of Leo's Join Date: Mar 2003 Location: Godzone Posts: 2,612 35 Photos	What it may have been, Slack, is just a little corrosion - invisible to the eye - built up on your input jack. Couple with a bit of dust, and bingo - no contact, just hum. Work the jackplug in and out a few times and all of a sudden it works again. I think Brother Tremo is lookin' after your best interests in suggesting a tech-check. If it is all original, those filter caps will be straining, and the little electros on the board will also be a bit sad. I've seen a 60's radio chassis which popped a cap - the stuff is like corrosive Space Invader - fills ever nook and cranny, and takes hours to pick out. If you have bad luck and the elements short inside, say goodbye to your power tranny and maybe tubes. __________________ My other Telecaster is a Thinline The Tele Bible, Ch 1, v 10 Love thy Telecaster, covet not thy neighbour's Strat!

February 18th, 2006, 08:26 PM	#4 (permalink)
David Barnett Poster Extraordinaire Join Date: Mar 2003 Location: LIttle Rock, AR Age: 52 Posts: 5,411	With no tubes, there should be no voltage anywhere except the bias supply, so if you actually did blow something, that's where I'd look first.

February 18th, 2006, 09:12 PM	#5 (permalink)
milocj Tele-Meister Join Date: Aug 2005 Location: Michigan Posts: 364 3 Photos	This is pretty obvious so don't get mad that I brought it up, but the rectifier tube and the 6V6s will interchange. Check that first.

February 18th, 2006, 09:37 PM	#7 (permalink)
slack Tele-Afflicted Join Date: Sep 2003 Location: Hollywood, CA Posts: 1,929	Just pulled the chassis. Everything looks fine. No blown caps, no broken joints, etc. In fact, it all remains 1964 original and untouched. The tubes I put in it came right out of a working Princeton. This one was the best sounding of my Princetons, last time it was working (based on original amps AND speakers).

February 19th, 2006, 03:32 PM	#12 (permalink)
slack Tele-Afflicted Join Date: Sep 2003 Location: Hollywood, CA Posts: 1,929	So, today it is working again. Apparently it's toying with me, making me look silly. I'm thinking it's a flakey tube.

February 19th, 2006, 06:54 PM	#14 (permalink)
Tremo Friend of Leo's Join Date: Mar 2003 Location: Silicon Valley, CA, USA Posts: 3,735	Look, Slack, no offense intended, but it is pretty clear that you have no idea what you're doing. I'd suggest that you take the amp to a tech before you blow something up.

February 21st, 2006, 12:38 AM	#17 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Lost Angeles and Orange County Posts: 7,128	I could take a look at her. I'm in Orange County. It's kinda hard to mess up an old Princeton like you're saying. I'd unplug her and check the solder joints first... then dried out caps would be the next suspect. They will look like working caps, so you can't really "eyeball" it for bad ones. If it craps out again, or starts killing tubes/fuses, checking voltages would give you a good place to start - THAT COULD ZAP YOU GOOD, so perhaps learn more about amps, or take her to someone.