I love the 5e3. Just not mine! Please help.

[JohnRose81]

Yes, sadly I couldn't get to Home Depot for a new multimeter. As soon as I get home around 5.30 EST I will recheck using the 2.5 and 10 volt ranges for those 2 pins on the pre-amp tubes.

The green wire of the AC cord is attached to the chassis. I bolted it down.

I'm unsure by your final question. How would I measure that. The black goes to the fuse and the white goes to the on/off switch. Are you wanting an AC reading of those two wires?

Also, I'm using NOS tubes for my 6V6's. Old GE tubes. They tested fine, but I'm seeing that I shouldn't use NOS tubes there. If so, I can replace them if need be.

[nashvillebill]

I see no reason why you shouldn't use NOS tubes there. Lots of folks run old 6V6's in their amps. In fact, when you get loud popping noises from touching preamp tubes, that is a good sign that there isn't a major problem with the power amp section (if there was, you wouldn't hear the pops).

There could be an argument made that it'd be better to use cheap 6V6's when debugging the amp, so as not to potentially expose good expensive tubes to a fault situation, but if the power amp section of the amp is working (and it appears to be) then the NOS tubes are fine, IMO.

[g1]

I'm unsure by your final question. How would I measure that. The black goes to the fuse and the white goes to the on/off switch. Are you wanting an AC reading of those two wires?

Looking for the AC voltage between those 2. So one probe to the black, other probe to the white.

[JohnRose81]

Hey hey. So I bought a digital reader. Screen is blow fun. Too late to return it so I'll do that tomorrow. I did get a couple readings like the filter caps are like 420 for the first one.

I got to your two wires and it was like 120. I can't remember. But I rechecked with the analog one and it read 60 if I was on the 300 setting and it read 120 of I was on the 250 setting. My analog is a m1015b if you want a screen shot of what I'm talking about.

[JohnRose81]

Also, if I have just the rectifier tube in, my filter caps show a much higher reading. Also, my normal channel volume pot is scratchy and cuts in and out I'm noticing. I've only been using the bright channel. Never thought about it.

[g1]

Well, as there is no 300 scale on that meter, it makes sense that the 300V range doesn't work right .
Sounds like all the weird readings were the meter though, so that is good news.
When you get the other meter and can get proper readings, things will progress.
It is normal for the voltage on the filter caps to go up when the other tubes are removed.

[Dave H]

Well, as there is no 300 scale on that meter, it makes sense that the 300V range doesn't work right .

I wondered why it would have a 250V and a 300V scale. They are too close together. The next logical scale after 250V is 500V. I think that is what the '300V' scale really is. The readings make sense if the '300V' scale is thought of as 500V full scale, 120V will then read 120 on both the 250V and ’300V’ scales. The meter is only rated for an input of 300V max so they have called the 500V scale '300V' for ‘elf and safety’ reasons, wonderful!

[g1]

Thanks Dave, makes perfect sense!
I would not recommend trying to measure more than 300V with this meter for safety reasons.

edit: seems there was another thread with some weird readings and the same meter was being used.

[JohnRose81]

Digital Multimeter Readings:

Tubes Starting with the 12AY7 and moving to the 5Y3

12AY7:
1: 148
2: 0
3: 2.3
4: 0
5: 0
6: 145
7: 0
8: 2.3
9: 0

12AX7:
1: 189
2: 2
3: 1.5
4: 0
5: 0
6: 234
7: 19
8: 53
9: 1

6V6:
1: X
2: 0
3: 420
4: 383
5: 25
6: 25
7: 0
8: 23

6V6:
1: X
2: 0
3: 419
4: 383
5: 120
6: 117
7: 0
8: 23

5Y3:
1: X
2: 428
3: X
4: 0
5: X
6: 0
7: X
8: 428

Filter Caps Starting with the one CLOSEST to the Power Supply

F1: 425
F2: 386
F3: 285

Fuse: 75 AC
Light: Top 3.3 AC Bottom 3.5 AC
Black and White Power Supply Wires: 122 AC

[eschertron]

I'm glad you have a new meter to use, I think this is getting somewhere now.

Are you on a DC-only scale? That's OK, but important info. I see zero (or thereabouts) on pins 4/5 and 9 of the preamp tubes. If they're working (and they are!), they'd have 6.3vac across the heaters. Or about 3.15vac from the pins to ground.

The 12AY7 looks normal. After that it starts to get weird. The 12AX7 side A (pins 1, 2, 3) shows 1.5v (about right) on the cathode but 2v on the grid. The grid of a properly-operating tube should *never* by more positive than the cathode. Excessive tube current and "red-plating" will occur. Maybe the 2v is an AC signal and there's some parasitic oscillations? This hypothesis, of course, conflicts with the guess above that you're on a DC-only scale. Oh, well.
The other side of the 12AX7 (side B) is probably a cathodyne phase inverter (correct me, please) and while the voltage between the grid and cathode is 'safe' by the above definition, the grid being THAT negative with respect to the cathode is effectively not conducting. Here's a spot to start looking at component values and voltages for the problem (take voltage readings on both sides of each component and mark it on the print). You will be able to find bad components or bad solder joints this way. And...

The plate and cathode voltages for both 6V6's look ballpark, but the grids (pin 5) are both off. If there was actually 120vdc on the grid of one of your power tubes, there would be smoke and noise and generally, mayhem. Re-measure these using both a DC scale and an AC scale if you can manually set them (usually there's a button that allows you to override the auto-select). Good voltages here will help narrow down the focus to the PI section.

last observation: the 70v to ground for the fuse (and from your previous posts, white and black power wires) tells me that your house wiring DOES NOT have the neutral and ground bonded in the distribution panel. Not too much of a thing, but be aware that with devices that only switch on the L1 side of the power wires you will have 70vac live in your device (to ground) even with it switched off. Probably not enough to send you to the hospital, but it'll sure give a tingle! Not to mention that anything over 40v is legally considered too dangerous to work on live without protective gear.

[JohnRose81]

Im not seeing my response post, so here it is again.

All of these readings are DC (the V with the ... under it) EXCEPT for the fuse, light, and black/white wire. I just retested using just DC again, and the numbers are the same. What would you like for me to AC (V~ icon)?

ALSO!!!! The 5 & 6 pins on the 6V6's is MV NOT V!

[eschertron]

ALSO!!!! The 5 & 6 pins on the 6V6's is MV NOT V!

Ah! Makes sense now So the pins 5 of the 6V6's are reading in the millivolt scale? That's good!

I'll find a 5E3 schem and look at the PI stage, that's where I suspect the trouble lies. There's been so much about the meter you were using in this thread, it might be of use to review the original situation... please expand on the low volume and lack of bass. Is that the main complaint?

[JohnRose81]

The schematic is towards the top of this thread. And yes. Maybe 1/3 volume and reduced bass. Normal channel volume pot is scratchy and cuts off as I roll the volume up and down.

[JohnRose81]

Maybe the fuse is wired backwards or the speaker is. Maybe too many grounds. Maybe not a good ground. Maybe I didn't solder the volume pot well enough to itself. Not sure. Double checked all. Seems good. Maybe I can Skype one of y'all.

[Chuck H]

With only the rectifier tube in your voltage should be higher. But how much higher??? Not 210 with tubes in and, what, 430 without? You certainly have some wiring errors. Can you post a few detailed photos of the build? We need to see the wiring details of every circuit. If we can read component values that's even better.