My Classic 30 DIED!!!

greentexasbandit · 02-09-2010, 03:36 AM

Hi Everyone!
Well, here's the deal...a couple weeks ago I was playing at church on my Classic 30. I left my amp sitting for a few minutes before the service started and when I got back to play, it didn't work anymore!!! I wasn't sure what was going on because the the power/pilot light was still on but nothing was coming out. I checked the tubes and none of them were lit up so I knew it wasn't a quick fix.

I was finally able to check it, I found that the P.T. and all the tubes were not heating up in the slightest. I found this odd because they're normally pretty hot!
I checked the fuses and they all still had continuity so I'm assuming they're fine. I checked power going into the P.T. and it read about 117 volts (normal), but when I checked the other side of the P.T. at the fuses, I was only able to get a 3-5ma reading on one of the wire sets. My thought is that the P.T. is blown, but I'm no expert which has led me here...to ask some experts.

Anyway, I would really appreciate any input you guys have...

Thanks for the help!

tubeswell · 02-09-2010, 04:40 AM

Quote:

Originally Posted by greentexasbandit

I'm just at a loss right now as to what comes next.

a trip to your tech. Those c30s are a dog to work on

Enzo · 02-09-2010, 07:49 AM

Did you actually REMOVE each fuse and measure it with an ohm meter while it was out of its clip? Your 10A heater fuse will seem to measure OK while it sits in its clip. Otherwise, we might check those couple 3w resistors in the heater string.

ermynn · 02-09-2010, 07:57 AM

hi

Look at the wire between the two cards (near the power capacitors) in your classic 30. they would be broken ...

Regards
Denis

greentexasbandit · 02-09-2010, 08:33 PM

Yes, I removed all fuses from their clips and measured them with an ohm meter...they all kept their continuity while they were out of the clips. I also took out all of the tubes and checked them as well.

greentexasbandit · 02-09-2010, 08:34 PM

I'll take a look at the wires between the cards...haven't checked those too closely yet. Thanks

Gunny · 02-09-2010, 10:00 PM

Isn't it possible that one (power) tube filament just failed open circuit? Since they are wired in series, it only takes one 'open' to the kill the set.

Try replacing the power output tubes (one at a time) with a known good one.

greentexasbandit · 02-09-2010, 10:08 PM

Hmmm...I tried changing them out in pairs because I still have the factory tubes, but didn't get anything out of it. I guess I should try one at a time though.

Enzo · 02-10-2010, 12:35 AM

Pretty darned unlikely that more than one heater is oopen, but it takes only seconds to check.
If the heaters do not light and the heater fuse is good, then you have a continuity problem. Either a broken jumper link, or an open series resistor. R71,72 are 3 ohm 5w, on the end of the center board near the fuses.

02-09-2010, 03:36 AM	#1
greentexasbandit Junior Member Join Date: Feb 2010 Posts: 4	My Classic 30 DIED!!! Hi Everyone! Well, here's the deal...a couple weeks ago I was playing at church on my Classic 30. I left my amp sitting for a few minutes before the service started and when I got back to play, it didn't work anymore!!! I wasn't sure what was going on because the the power/pilot light was still on but nothing was coming out. I checked the tubes and none of them were lit up so I knew it wasn't a quick fix. I was finally able to check it, I found that the P.T. and all the tubes were not heating up in the slightest. I found this odd because they're normally pretty hot! I checked the fuses and they all still had continuity so I'm assuming they're fine. I checked power going into the P.T. and it read about 117 volts (normal), but when I checked the other side of the P.T. at the fuses, I was only able to get a 3-5ma reading on one of the wire sets. My thought is that the P.T. is blown, but I'm no expert which has led me here...to ask some experts. Anyway, I would really appreciate any input you guys have... Thanks for the help! Last edited by greentexasbandit; 02-09-2010 at 05:32 AM.

02-09-2010, 07:49 AM	#3
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Did you actually REMOVE each fuse and measure it with an ohm meter while it was out of its clip? Your 10A heater fuse will seem to measure OK while it sits in its clip. Otherwise, we might check those couple 3w resistors in the heater string. __________________ Education is what you're left with after you have forgotten what you have learned.

02-09-2010, 10:08 PM	#8
greentexasbandit Junior Member Join Date: Feb 2010 Posts: 4	Hmmm...I tried changing them out in pairs because I still have the factory tubes, but didn't get anything out of it. I guess I should try one at a time though. Last edited by greentexasbandit; 02-09-2010 at 11:10 PM.

02-10-2010, 12:35 AM	#9
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Pretty darned unlikely that more than one heater is oopen, but it takes only seconds to check. If the heaters do not light and the heater fuse is good, then you have a continuity problem. Either a broken jumper link, or an open series resistor. R71,72 are 3 ohm 5w, on the end of the center board near the fuses. __________________ Education is what you're left with after you have forgotten what you have learned.

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02-09-2010, 07:57 AM	#4
ermynn Junior Member Join Date: Nov 2009 Posts: 1	hi Look at the wire between the two cards (near the power capacitors) in your classic 30. they would be broken ... Regards Denis

02-09-2010, 08:33 PM	#5
greentexasbandit Junior Member Join Date: Feb 2010 Posts: 4	Yes, I removed all fuses from their clips and measured them with an ohm meter...they all kept their continuity while they were out of the clips. I also took out all of the tubes and checked them as well.

02-09-2010, 08:34 PM	#6
greentexasbandit Junior Member Join Date: Feb 2010 Posts: 4	I'll take a look at the wires between the cards...haven't checked those too closely yet. Thanks

02-09-2010, 10:00 PM	#7
Gunny Member Join Date: Oct 2008 Location: Ontario, Canada Posts: 40	Isn't it possible that one (power) tube filament just failed open circuit? Since they are wired in series, it only takes one 'open' to the kill the set. Try replacing the power output tubes (one at a time) with a known good one.

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