12002: 2" OT

Moderator: VelvetGeorge

Post Reply
User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Sun Oct 09, 2011 9:30 pm

Lifted both 100k plate resistors. Both read 100k.
12000 Metro Kit

somethin'else
Senior Member
Posts: 1147
Joined: Tue Mar 18, 2008 10:19 pm
Just the numbers in order: 7
Location: the dirty south

Re: 12002: 2" OT

Post by somethin'else » Sun Oct 09, 2011 10:08 pm

Oy, that PI tube pin1 at 220 sounds decent, but you're still variac'd down, so no cigar. Something's letting that B+ fly on through, not dropping or going to ground along the way.

What are your pin 6 voltages on V1 & V2? Same as pin1 or even higher?

As Valvestorm said, you might as well post the whole chart. Keep 'er at 350vdc and record everything.

How'd those tubes work out in another amp?
dave

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Sun Oct 09, 2011 10:12 pm

Tomorrow. :bang:

Pins 1 and 6 are the same voltage on v1, v2.
12000 Metro Kit

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 7:34 am

Tested all 3 preamp tubes. All working fine.
12000 Metro Kit

vh junkie
Senior Member
Posts: 1288
Joined: Tue Jan 13, 2009 7:07 pm

Re: 12002: 2" OT

Post by vh junkie » Mon Oct 10, 2011 8:44 am

I wonder if one of your grounds is missing.
Tone control and volume grounds, OR controls not connected to the right points on the board?
Ground at the 33/33 cap?
Grounds at the cathode caps/resistors for each preamp stage?
Check the voltages from ground/LOv side to pos/HIv side of each cap. Do these makes sense compared to your readings from ground to the HIv sides?

Does the PT have a set of lower voltage taps? 520 seems like the V one would use with older sturdier tubes...
Is the PT getting hot?
"With all due respect, sir, you're beginning to bore the hell out of me."
- Gunny Highway

User avatar
Strat78
Senior Member
Posts: 3093
Joined: Fri Aug 03, 2007 12:38 pm
Just the numbers in order: 13492
Location: though I'm standing still, I'm in a moving place.

Re: 12002: 2" OT

Post by Strat78 » Mon Oct 10, 2011 10:57 am

T2562 PT wire color codes:
PRIMARY:
ORANGE = common nuetral
WHITE/red = 100V Japan...
RED= 120V
BROWN= 220V
BLUE = 230V
PURPLE = 240V

SECONDARY:
Black & Blue= High Voltage to diodes or stand-by....
Yellow = High Voltage Center-Tap....connect between first group of caps...
Thick BLACK wire = Heaters
Green wires go to ground...
White = bias

What kind of switches are those, double check the wiring.

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 11:00 am

Thinking about the fact I had heater voltage but the v1/2 tubes would not light up. I put the probe on the solder joints. When I put the probe on the solder tabs for the blue heater....nothing. Looking at the solder joints closley i couls see some of the blue insulation had sucked through on both V1 and V2. I removed both and resoldered.

Thats it.... :roll:

The insulation sucked through and coated the solder joint underneath and created a thin barrier. The joints look soldered but are not connecting with the tabs. The voltage bridged from v3 right to v1 but never got to the tubes. The probe was making making me think the sockets were getting voltage.
Attachments
AMP REPAIR THANKSGIVING 006.JPG
AMP REPAIR THANKSGIVING 006.JPG (101.07 KiB) Viewed 866 times
AMP REPAIR THANKSGIVING 007.JPG
AMP REPAIR THANKSGIVING 007.JPG (104.54 KiB) Viewed 866 times
12000 Metro Kit

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 11:03 am

Stuck in some Tubetramp Sylvania's and Mesa EL34's.
Attachments
CHART 001.JPG
CHART 001.JPG (132.94 KiB) Viewed 865 times
12000 Metro Kit

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 11:09 am

When I soldered the heaters I had the insulation right up against the tabs. They looked like solid soldering joints, but were insulated from the tabs. Very thin barrier trapped between the wire and tab. If I had measured from the bottom of a tab or better still, inside the socket holes from the other side, I would have had this all fiqured out last week. :P
12000 Metro Kit

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 11:13 am

vh junkie wrote:I wonder if one of your grounds is missing.
Tone control and volume grounds, OR controls not connected to the right points on the board?
Ground at the 33/33 cap?
Grounds at the cathode caps/resistors for each preamp stage?
Check the voltages from ground/LOv side to pos/HIv side of each cap. Do these makes sense compared to your readings from ground to the HIv sides?

Does the PT have a set of lower voltage taps? 520 seems like the V one would use with older sturdier tubes...
Is the PT getting hot?
Yeah, I checked all the grounds thinking the same thing, but they were all correct. Without the tubes working because of the heaters, I guess no voltage was being distributed to get to the grounds and bleed off reducing where it should have been.
12000 Metro Kit

User avatar
Strat78
Senior Member
Posts: 3093
Joined: Fri Aug 03, 2007 12:38 pm
Just the numbers in order: 13492
Location: though I'm standing still, I'm in a moving place.

Re: 12002: 2" OT

Post by Strat78 » Mon Oct 10, 2011 11:46 am

Whoo hoo, back on track, what a ride that was, awesome. One of those magnifying lamps is a must for our old eyes. I check each solder joint after it is made, it slows things down, but gives you piece of mind. :) This thread will be a huge help for all those guys with 12series chassis being used as book ends. Come guys, where are the builds?

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 12:14 pm

If I had only checked inside the socket holes. Gheez! :roll:

Biased down to -37. I should probably go a bit lower. I'll leave it set up the way it is for a week or so to work out any bugs before adding the 6ca7s and redoing the bias at 90v.

Just had it plugged in with an Aracom. Sounds great! That OT is kick ass!
12000 Metro Kit

User avatar
vanhalen5150
Senior Member
Posts: 7307
Joined: Wed Sep 10, 2008 3:13 pm
Just the numbers in order: 7
Location: Halifax, Canada

Re: 12002: 2" OT

Post by vanhalen5150 » Mon Oct 10, 2011 12:16 pm

Thanks for the help and input guys! Much appreciated! :D

Thanksgiving here so I'll be having a few....... :rock:
12000 Metro Kit

somethin'else
Senior Member
Posts: 1147
Joined: Tue Mar 18, 2008 10:19 pm
Just the numbers in order: 7
Location: the dirty south

Re: 12002: 2" OT

Post by somethin'else » Mon Oct 10, 2011 4:07 pm

:clap: :clap: :clap:

Congrats man! Even with all your great pics that one was hard to spot. I found myself trying to peek under your board a few times but my computer wouldn't let me... :lol:

+1 on the magnifying lamp. Taking the time sure helps cope with the tension to jam as you build.

The hardest part always seems to be the last step of checking everything and firing it up and checking everything. It's like 4th quarter, you're on the 3 yard line, 4th down, and you're down by 6. 'Cause at that point (mentally for me anyway) your already playing guitar! And God forbid there's something to troubleshoot, 'cause you've already over-stepped into right brain mode for the jams... :lol: Fuzzy indeed.

Happy Thanksgiving, have a drink on 'us', and please, spit out some Unchained or something with that hot dog amp!

:toast:
dave

User avatar
Strat78
Senior Member
Posts: 3093
Joined: Fri Aug 03, 2007 12:38 pm
Just the numbers in order: 13492
Location: though I'm standing still, I'm in a moving place.

Re: 12002: 2" OT

Post by Strat78 » Mon Oct 10, 2011 4:54 pm

vh junkie wrote:tubes...
Is the PT getting hot?
Keep all your senses in play: touch, sight and smell. I'm always feeling up my OT and PT, eyeballing the tubes and sniffing around the sockets. Ah, to take 450v on the nose, now that would be interesting. :mrgreen: Happy Thanks Giving, Kraft Dinner and all!

Post Reply