No sound from first 5e3 build PLEASE HELP!

[arielja87]

So this was my absolute first attempt at building an amp. I followed a ceriatone layout pretty much exactly but I'm not getting any sound from the amp. Also in the pictures you will see that the entire chassis layout is backwards. This is because I drilled all the holes myself but had to take the flat steel chassis to a metal shop to get it bent. Somehow I forgot to specify the direction I wanted the folds made so the sides of the chassis were bent the wrong way. Rather than create a new chassis i just made a mirror image layout in paint and went from that. All the connections are still the same. When I plug in an instrument cable and touch the tip with my finger i get a very very faint buzz. The pots will all affect the buzz but otherwise no sound. Indicator lights up and tubes all light up and get warm. First guess is that its an issue with the input jack wiring for which i kind of used both the ceriatone layout and the tube depot layout. I know its not pretty but like i said, first time. Any help would be GREATLY appreciated. pictures attached

Tube Voltages
V1
pin 1: 177.2
pin 2: 0 - 2 mV
pins 3, 8: 1.57
pins 4, 5, 9: 3
pin 6: 144.5
pin 7: 0 - 2mV

V2
pin 1: 156
pin 2: varies in mV
pin 3: 1.43
pins 4, 5, 9: 3
pin 6: 201.5
pin 7: 17.4
pin 8: 49.4

V3
pin 1, nothing attatched
pins 2, 7: 3v
pin 3: 374.4
pin 4: 326.8
pin 5: around 0.8
pin 6: around 0.8
pin 8: 20.87

V4
pin 1, nothing attached
pins 2, 7: 3
pin 3: 377
pin 4: 332.8
pin 5: around 0.8
pin 6: around 0.8
pin 8: 20.28

V5
pins 2, 8: 389
pins 4, 6: 9.5 dc, 345 ac

[loudthud]

Voltages look good. I would guess a short at the speaker jack, but the photo looks ok. Might possibly be a short to ground at the input jacks or maybe at the pots.

[Jazz P Bass]

Maybe it is time to dynamically test the amp.
You could take a few Vac readings with a signal going in to the input jack.
The attached schematic has Ac signals marked in a circle.
DC are in a square.

[Brad1]

You may want to make another copy of your schematic/layout and trace back through every single connection, double-check everything, and mark them as you go. You can't assume you wired up everything properly the first time. You may also want to re-solder any suspicious-looking joints, and try to get some of them dressed a little better, so there aren't bare red wires being scary-close to grounded nuts, etc.

As relatively simple as those amps are, they can still get a bit confusing at times, and having done it backwards couldn't have made it any easier.

A little patience...a lot of double-checking. Check everything, again. (Trust me. I've done the same thing...only not backwards!)

Brad1

[arielja87]

Thanks so much for the help guys! I checked the ac voltage where the yellow secondary wire from the OT connects to the speaker jack and I get nothing. According to that schematic jazz posted, it seems I should be getting around 10 VAC there. Could this mean a bad OT?

[loudthud]

Not likely to be a bad transformer if the ohms are ok. With a speaker plugged in, you should see a very low resistance across the speaker terminals, perhaps 0.3 ohms (too low for most meters to measure accurately). From pin 3 of one 6V6 to pin 3 of the other 6V6 about 600 ohms. Note that there still could be a short at the speaker jack or in the speaker cable.

Note that when you reversed the layout in Paint, you reversed the connections to the pots, they will operate backwards. Did you take this into account?

Set the pots to mid rotation. V2 pin 2 should measure about 500K to ground. This will vary some but you shouldn't see a short to ground.

Edit: I messed up and wrote 50K to ground because of the wacky way pots operate in the 5E3 doh!

[loudthud]

The connections to the input jacks may also be messed up. The picture you posted is too dark. Look at the Visitor Messages section in my profile and look for a link to a thread where you ohm the input jacks to V1. Click on the name above my picture and click on View Profile.

[arielja87]

Ok thats good news. ohms are good. Yes, i did take the mirror image into account when wiring the pots (after a couple solder joints) but I caught this pretty quickly so the pots are wired normally, left tab to ground, middle is the same. process of elimination did the rest. When pots are at mid rotation I actually got about 0.5 M ohms or 500K to ground. Is that wacky?

[loudthud]

500K is the correct reading, I edited my post above. You must have taken into account that reversing the layout in Paint would also mess up the connections to the tube socket pins. Otherwise your voltages would all be wrong.

Did you do the ohm checks from the guitar cord to the pins on V1?

[arielja87]

[QUOTE=loudthud;285207]You must have taken into account that reversing the layout in Paint would also mess up the connections to the tube socket pins. Otherwise your voltages would all be wrong./QUOTE]

Yea luckily the pins were numbered on the layout and on the tube sockets. The Octal sockets were labeled, I assumed the 9 pin sockets also were numbered clockwise starting with the first pin clockwise of the gap.

Did you do the ohm checks from the guitar cord to the pins on V1?

Yes. ended up rewiring the input jacks. now everything checks out except when I measure the bright channel. From the tip of an instrument cable to V1, pin 2, I'm getting 1.025M ohms on the #1 input and 168.8k ohms on the #2 input

[arielja87]

GOT IT!! inside the speaker phone plug the positive wire was touching the shield. thanks for all the help!