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So after a long build process, I finally made my last solder. I have no experience with electronics so I had to do a lot of reading and research and I went pretty slow. I think my soldering could be improved (especially on the bus bars and grounds) and after some frustration with trying to get the wire to dress properly, I just did what I could to make it somewhat neat.

Let me know what you think. Anything look strange or out of place? The review of everything and figuring out how to take readings properly is the next step.

It's been fun so far and I'm looking forward to sparking it up.

Thanks to cigarman and 2X6L6, your pictures were a big help.

Steve

It's a hard amp to keep looking neat inside. Lots of wires and not a lot of extra space. Your build looks good, though.

Double check all your wiring and solder connections. If possible use an ohm meter to verify that everything that's supposed to be connected actually is. Then power it up and check all the voltages like it says in the manual.

I like to power amps up first with no tubes and check all the AC voltages. Then with just the rectifier and check the B+. Then add the preamp tubes and check the voltages again. And finally add the power amp tubes and a speaker.

The voltages will read high until all the tubes are in place.

Good luck!

Looks GREAT, Steve. I really like the way you did the contour switch. Despite my best efforts, mine looks like hell. But it works well. Looking for a tone report next!

Thanks guys. Good advice Mitch. I'll start measuring tonight if all goes well.
Thanks 2X6L6, that switch is tricky. I'm not thrilled with how it looks, but function over form in this case.

Well, after a lot of reading and research, I still can't find a plain english explanation for how to measure voltages. My confusion is over when to measure to ground and when to measure across pins. And whether to use AC or DC. Pretty basic I know, but it's all new to me. These are all measured with no tubes installed.

It passed the smoke test fine and I get 330 V on pins 4 and 6 of V7 (measured to ground) and 10 V across pin 2 & 8.

On V4 I get (all to ground) 220V DC on pin 1, 12V AC pin 3, and 7.3V AC across pins 4,5 & 9.

After a lot of dial flipping and trying different ways to measure, I can't figure out how to get any measurements close to what's in the chart in the manual. Either something is wrong or I'm doing it very wrong. I was hoping for noise tonight but I'm reluctant to install any tubes until I can tell if it's okay.

Thoughts anyone?

In general, everything before the rectifier will be AC and all of the 6.3v heater runs will be AC as well.

After the rectifier all of the high voltage points will be DC. The function of the rectifier is to convert the AC from the transformer to the DC the tubes need to operate.

When measuring the heater voltages (or filament) you measure from heater pin to heater pin AC - pins 5 to 9 on a 12AX7 for example. Everything else you pretty much just measure pin to ground.

You are never going to get exactly the same readings as someone else but you should be within 10 to 15%. Also everything will read way high until you plug in all the tubes.

Thanks Stephen. That helps. I'll give it another try tonight.

Sorry dtp, read that fast today and missed it was you. Thanks again, I appreciate the help.

Well, no luck. Readings are still off but I decided to try some tubes and see what's up. I get a loud hum on both channels. There was a fast pulse to the static/hum at first. I tried the crunch/munch switch and there's fairly loud crackling as I switch it. The pulsing stopped after I flicked it the first time. Now it's just loud static/hum.

Back to the drawing board. Ah well. Will try to get some readings that make sense and post them.

Pull out the EL84's and check your B+ voltages again. Set your meter to DC volts and measure from ground to the positive terminals of the can capacitor and all the 20uF filter capacitors. The Standby switch has to be closed for this test because none of the filter capacitors will be connected if it's open.

This will tell you if the power supply is working properly.

Also check to make sure everything that's supposed to be connected to ground actually is, especially the filter capacitors and the input jacks. Set your meter to ohms and measure from the main chassis ground to the various components that should connect to ground. You should get a very low ohms reading, the same as you get when you touch the two probes together.

Good luck. Your build generally looks good so the amp is close to working. Just a few bugs to iron out.

Thanks Mitch, that helps a lot. I'll do all that.

I know that the real problem is my lack of experience and not having a good grasp of how to use the metre and what the results mean. But that's okay because it just means I'll have to learn more.

At least I'll really be ready for my next build...

It's all good man. I help to be helpful, not for the glory.

Yeah I agree with Mitch... sounds like a grounding issue. Post the readings you are getting here in a format similar to what's in the table in your manual. It could help us narrow the search for the issue you are having.

Interpreting meter readings isn't always an exact science. Often it just lets us know something is wonky and we need to look in that general area for the problem.

Does your meter have a continuity test setting? It gives an audible sound when there is a clear path (good continuity) and no sound if there isn't. If it does, set it to that and for any component that connects directly to ground, test from the lead of that component (the side that goes to ground) to the chassis. Sound means good connection, no sound means there is a break in the circuit (bad ground) and it will be between that component and ground. Possibly a bad solder joint or even a forgotten one (lol I've done it) or it's going to the wrong spot altogether.

Well good news! I found the problem and managed to get it working. Thanks to everyone who helped me out. I followed all your directions and I probably wouldn't have gotten there without your help.

It was a tricky problem. I had reviewed all my work twice and then checked all the grounds and it all seemed good. I followed dtp’s suggestion to use the audio tone. All seemed good till I rechecked the ground to the mains plug. I noticed it moved a little when I checked it. Turns out the wire was broken but resting up against the solder joint on the plug, so it looked fine and likely had intermittent contact. It had been fine when I touched the lug with the metre, but when I touched the wire it moved. I’m not sure how or when it broke. Long story short, I fixed it and redid all the measurements, now with a much better understanding of what I was supposed to do.

Here’s what I ended up with:
1 2 3 4 5 6 7 8 9
V1 91.5 1.7 159 1.7
V2 143.5 1.61 1.6 1.4
V3 171.9 1.35 283 171.2
V4 254.4 47.2 72.2 266.2 49.1 72.2
V5 7.9 388 243.1
V6 8.1 387 243.1
V7 397

Best of all, it sounds great. Channel 1 has a little noise (little squealing noises) when I stop playing sometimes, but it sounds good. The contour switch is pretty subtle but does go from thick to thinner. Channel 2 is great all around. This little bugger is loud!

There’s a volume drop when I use the crunch/munch switch. I assume the louder one is the munch (vox?) setting. The boost switch works fine as well. It’s a pretty bright amp (which I like).
So it seems I have a few little things to figure out, but I want to play it for a while before I try installing the VRM switch.

Thanks again everyone. I really appreciated it. It’s been a huge learning experience for someone who knew nothing about electronics. I still have to get to know the amp, but l I have a jam tomorrow night and I have a fantastic new amp to take with me.

Well it looks like the formatting of my table went to hell. Sorry about that. It all matches the columns in the manual.

Good job!!! I've had a similar issue as yours, as well as bad solder joints - all too common, but fixable. Great news. Killer amp, isn't it?