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Odd... now the preamp seems to be ok and the power tube has got problems.
I was looking at the most recent photo you sent.. Some of the soldering on the turrets look at little suspect. I'd unplug the amp and let the B+ die off ( check with voltmeter!!!) and touch up your soldering, specially on the turrets. The solder should flow smoothly into the hole and harden up in a nice mound on top of the turret. Hopefully that spark was at a bad solder joint and not anything more.

ok, I've got a bunch of (hopefully helpful) pictures for you guys.

http://i663.photobucket.com/albums/uu35 ... 173317.jpg

http://i663.photobucket.com/albums/uu35 ... 173307.jpg

http://i663.photobucket.com/albums/uu35 ... 173254.jpg

http://i663.photobucket.com/albums/uu35 ... 173243.jpg

http://i663.photobucket.com/albums/uu35 ... 173221.jpg

http://i663.photobucket.com/albums/uu35 ... 173148.jpg

http://i663.photobucket.com/albums/uu35 ... 3753-1.jpg

and more:

http://i663.photobucket.com/albums/uu35 ... 3721-1.jpg

http://i663.photobucket.com/albums/uu35 ... 173428.jpg

http://i663.photobucket.com/albums/uu35 ... 173410.jpg

http://i663.photobucket.com/albums/uu35 ... 173354.jpg

http://i663.photobucket.com/albums/uu35 ... 173833.jpg

http://i663.photobucket.com/albums/uu35 ... 173804.jpg

http://i663.photobucket.com/albums/uu35 ... 173452.jpg

please ignore my dirty jeans, they were the closest thing I had to use as a 'stand'

Some of the connections at the power tube could be cleaned up. I could see some suspects. Also the wire going from the junction of the 1K resistors to the board looks rough
Check the continuity to the tube pin 8 to cathode switch through to the 750 ohm resistor in the 6V6 mode. Your voltages are high and that indicates the 6V6 is not running. The low voltage you measured confirms that.

_________________
Stephen
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i'm not getting any readings on pin 8, the switch, or the resistor. Is it possible i fried the switch? regardless I'll rewire it tonight and give that a try.

Even if that switch is shorted or open you should still have a connection from the cathode. With the amp off and unplugged you should be able to measure a resistance of approx 300 to 800 ohms from pin 8 to ground after the cap charges up. (talking output tube here). If not, check your connections. You won't have any voltage on the cathode (pin8) with no tube installed. You should have around 400 volts on the plate (pin 3) slightly higher with no tube.
Stew

i rewired pin 8 and the switch. all the measurements are what they should be now I believe. They match what you and the layout say.

And now??..................any sound?

I found a mistake which might be the problem... I'm not sure. On the ohm selector I have the outputs wired up to C instead of A. I'll fix it once the caps drain and see what happens...


...ok, fixed the wire. There's sound... kinda. When i powered up I heard two pops. If i pull the volume knob it pops and due to my clumsiness i discovered that if I bump the power tube it pops. No sound other than that though.

just did some poking around with a multimeter. there were two joints making noises when I tested them. They were responding to the volume controls. I'll reflow them and check the measurements again.


ok, a question to clarify stuff. How should the 6v6/6L6 switch be positioned for a 6v6 tube? pointing up towards the transformers or down away from them?

redid the joints and got measurements of

412 on the 50uf
29 on the 750w
326 on the 33uf
160 on the 220k resistor
147 on the 220k/.01uf
1.9 on thr 2k7,.047 and 1uf
1.7 on the 2k7 that goes to pin 1.

"1.7 on the 2k7 that goes to pin 1."

Pin1?!!!!!
The bias switch...sort of depends how you've mounted it in the chassis. With the amp off. and you measure resistance to ground from pin 8 of the output tube... 750 ohms is the 6v6 position and the lesser value (275 ish) is the 6l6 position.

That impedance switch... it doesn't have 1,2,3,A marked on it?

pin 8 i mean, my bad.

thanks. that's what i thought, got it labelled so i won't forget

any idea on what I should try next?

you're at the point where I think we'll start checking the audio path backwards from the output to the input.
You can fire her up with tubes and set up the voltmeter to check some voltages. Turn up the volume half way or so.
Touch the voltmeter probe to pin 5 of V2 (output tube). You should hear a pop or some noise/hum. If you hear something that's good! now move to V1. Touch the probe to pin7 of v1. You should hear some noise/hum/pop. Reduce the volume if too loud. If you hear something move to pin2 of V1...same deal.
let us know where the results.
Stew

ok, i did that and got readings of 0 for all of them. The pin 5 of V2 and pin 7 of V1 hummed very quietly. Pin 2 on V1 didn't hum at all.

Was the "gain" pot turned up for that last part.....sorry I should have told you that. If it was and there is no noise/hum when touching pin2 then that means there's no signal getting from the first triode on V1 to the second. that sorta points to the 'Gain" pot and/or the tweed/tude switch associated with the gain pot. That would be where I'd closely check your wiring.
Stew
PS I just looked at the docs again On the schematic there is a "gain" and "volume" and on the colour diagram he has "volume" and "master" So both need to be turned up for these tests and the "volume"/tude/tweed controls should be checked.
Stew

i had all the controls set about halfway. I'll check my wiring and soldering tomorrow if I get a chance. I'm headed back to school tomorrow so I'll only be able to work on it on weekends. worth the 4hr drive though

Hi guys, I'm back.

I fixed the wiring from the board to the VRM which was incorrect and it had some strange results.

When I turn the VRM to 9-10 i get a very soft hum.
After i fixed the wires I measures (with tubes installed and VRM at idle, all other controls at 12 oclock) and got

40 on the first 50uf cap. With the power level maxed its 416.
448 on the second 50uf cap. When I maxed the power level it went down to 425.

.074 on the far right .047yf cap on the layout
23 at the .01 uf cap
26 at the 220k resistor
35 on the 33uf cap.
2 at the 750 5w resistor.

all very low. Any idea what I should check?

That's what the VRM is supposed to do. The output power of the amp is reduced with the VRM by lowering the voltages throughout the amp. With the vrm turned up full ...yes I would expect you'd hear a little hum because now the amp is at full power.
I would suggest that further tests and measurements be done with the VRM near max so we can figure out if there are further problems.
A while back you reported that you there was no sound when you touched the grid of the first tube (pin 2) . That's where we need to investigate.
Stew

Hey guys, I'm back for a few days. Gonna get back into troubleshooting tomorrow morning. I'll take some measurements with the VRM maxed and double check in 2. Thanks

Ok, measurements at points shown on the layout, tubes installed and VRM maxed. All other controls halfway:


First 50uf cap: 415DC

First 750 5w resistor: 29DC

Second 33uf Cap: 330DC

2k7 Resistor: 1.7DC

220k Resistor: 167DC

.01 uf cap/220k resistor: 154DC (this connection also pops when i measure it, I'm not sure if its supposed to. I think it
is,its the only one that does that though.

2k7, .047uf and 1 uf: 1.8DC



While I wait a response I guess I'll reflow the joints connecting the preamp tube as the measurements were a little low there. Thanks again guys