Metropoulos Forum

Lifted both 100k plate resistors. Both read 100k.

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?

Tomorrow.

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

Tested all 3 preamp tubes. All working fine.

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?

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.

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....

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.

Stuck in some Tubetramp Sylvania's and Mesa EL34's.

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.

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.

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?

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

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!

Thanks for the help and input guys! Much appreciated!

Thanksgiving here so I'll be having a few.......

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...

+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... Fuzzy indeed.

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

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. Happy Thanks Giving, Kraft Dinner and all!