Too high voltage? (Solved)

[Oddvar R]

Hi again. I have what might be an issue with the voltage from the filtercaps:

Into the rectifier board: 660v
Into FC: 460v
B5 421v
B4 421v
B3 453v
B2 460v

According to the schematics the voltage B4/B5 should be 324 and 316v-
The voltage after the 10k wiper also seem to be high,

If this is too high, what is thereto be done about it?

[sluckey]

Got tubes?

[drew]

Oddvar, why do you keep starting new threads every time you have a new question about this same amp? It would be much easier for people to help you if the information about your build progress was not fragmented in a dozen different discussions.

[pompeiisneaks]

Yes, it's usually best to keep any troubleshooting on a specific amp build into one thread so all previous status etc is viewable by those trying to help.

As sluckey stated, if you don't have the tubes installed the voltages are going to be way high and wrong, because there are no tubes inside conducting and drawing current and lowering the voltages etc.

~Phil

[Oddvar R]

Sorry if I violated any good behavior here, I thought one post one answer, but I'll be better in the future.

[pompeiisneaks]

Sorry if I violated any good behavior here, I thought one post one answer, but I'll be better in the future.

Not the end of the world, just making sure you're aware of it, and you are.

Thanks,

~Phil

[donvan]

Hi Oddvar,
It's also good practice to answer questions when you are trying to solve issues. Sluckey asked a very relevant question that you ignored.
Does your amp currently have tubes in it?

If not, you can expect higher voltages because the power supply is not seeing the load that it was designed for.

[Roe]

try to install the power tubes and to biasthem.

[Oddvar R]

Hi guys, I have had me some amp working. Sorry about not answering you Sluckey, you've been a great help in many projects. I have tried with every alternative, with or without tubes What it all has boiled down to now, is that when I removed the 4 ohm to the NFB 4.7k resistor, it seems to be working, at least I get sound from it, not great sound at the moment, but still. I misread the layout on a couple of places, Changed direction on the adjustment pots, and in the blue circle I didn't see the dotted lines.
I have bought a set of PCB's from Erwin, since the set I have has two different sets of layouts, which was very confusing in the beginning, but now I feel I have a better understanding of the amp, so I will install, maybe rebuild the hole amp when I get those.

So thanks for the help guys, very nice.
(And remember, some of us do this for fun, as a hobby.)

[norburybrook]

Hi guys, I have had me some amp working. Sorry about not answering you Sluckey, you've been a great help in many projects. I have tried with every alternative, with or without tubes What it all has boiled down to now, is that when I removed the 4 ohm to the NFB 4.7k resistor, it seems to be working, at least I get sound from it, not great sound at the moment, but still. I misread the layout on a couple of places, Changed direction on the adjustment pots, and in the blue circle I didn't see the dotted lines.
I have bought a set of PCB's from Erwin, since the set I have has two different sets of layouts, which was very confusing in the beginning, but now I feel I have a better understanding of the amp, so I will install, maybe rebuild the hole amp when I get those.

So thanks for the help guys, very nice.
(And remember, some of us do this for fun, as a hobby.)

if it's better with the NFB disconnected then you have your output primaries the wrong way round. That's probably the Blue and brown wires going to pin 3 on your 6L6's



M

[Oddvar R]

I am using this OT, this build has 4 EL34. So, what do you suggest? :

[Oddvar R]

M. You nailed it. Thanks.

[Oddvar R]

A couple of things are a bit unclear(for now), on the pot closest to the jacks there is hardly visible: 22m?

And the half watt connection I presume there is a LED of some kind, any wattage there? And negative foes to ground, or?

What voltage, if any, should go from the 12v to the pedal jack, pin 1 and 5? I don't get any readings here, so that might be why the overdrive isn't responding? Any suggestions?
On the pic there is something written in red, circled, that isn't readable? Important?
And is the coax connected to the right pin on the Drive going to the 100k resistor, it seems to stop a bit before the point?

[pompeiisneaks]

A couple of things are a bit unclear(for now), on the pot closest to the jacks there is hardly visible: 22m?

And the half watt connection I presume there is a LED of some kind, any wattage there? And negative foes to ground, or?

What voltage, if any, should go from the 12v to the pedal jack, pin 1 and 5? I don't get any readings here, so that might be why the overdrive isn't responding? Any suggestions?
On the pic there is something written in red, circled, that isn't readable? Important?
And is the coax connected to the right pin on the Drive going to the 100k resistor, it seems to stop a bit before the point?

1. there are two 22m resistors as part of the tone stack lift in the amps. They both are linked to one of the relays. Not sure if this is what you're referring to, as you have no picture or link to refer to.
2. Half watt connection should have one route that directly connects the grids of one power tube from either side of the halves of the Push Pull pairs to ground, (that's full power) and the other switch output should connect to the two larger resistors (10k on the 124 I built) to the anode of the led, then the cathode of the led to ground so the valves are basically at cutoff, the LED then lights up because enough current goes through it to light it up when those two are engaged.
3. you wno't get 12V across the loop until the relay is engaged or the footswitch is closed. If you've got it wired correctly either the footswtich or the back panels switches close the circuit to engage the relay. Make sure your relay's aren't polarity set, or if they are, make sure you have the + and 1 of the relay power supply connected correctly.
4. I'm not sure which layout you're referering to, as this post just names it 'Too much voltage' Which build is this? 124, 183 etc? I'm not sure what you're looking at. On the 124 I built there is a coax that goes from a 100k resistor to the od drive pot and another from the 180k resistor to the od volume pot. Is that what your'e referring to? If you're unsure always check schematics to understand routing, and/or look at the other dumbles, they're VERY similar except for a few minor tweaks of components. (edit just re-looked at the pic you have. Yes that coax connects. I don't think there would ever be a wire run to the very edge of an eyelet to then do nothing. But it never hurts to ask)

[Oddvar R]

Hi and thanks for a good answer. It's #183, and the reason I ask this under the "too high voltage", is because I was told to keep it to one post and not spread it around.

If you look at the pic, there is something that seems like 22m written on the pot, between pins. I am just checking so I don't miss out something.

When it comes to the coax, I figured it connects to the 100k, but since it differed from the one next to it, I just wanted to make sure.

The amp functions great on all other parts but the Overdrive section doesn't respond, so I am checking all possibilities.