Low heater voltage- how raise it up higher?

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Maybe things would be better when I wire the primary for 230V instead of 240V. The wall voltage today is 233V

Interesting. That could be the culprit. Let us know what happens.

Ok. 230V wiring performed. Heaters up to 5.9V across the heaters, but all values went up. The PT is rated for 300-0-300 HT.
Now the B+ is way up.
What do you suggest? Start tweaking the cathode bias resistor or wire the PT back to 240V ? Or put a resistor between the EZ81 and the first filter cap?
Second line of measurements is 230V , first line is 240V

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[Bieworm]

Anyone?

[JMPGuitars]

Well, 303 is a lot closer to the 300 spec than 289 is. That tells me that's where the PT is probably supposed to be. OTOH, 18W transformers are usually spec'd at 290-0-290 (some as low as 275-0-275) which is probably why your voltages are better the other way.

My suggestion is that since the variance in heater voltage isn't that significant, switch it back unless somebody smarter tells you not to.

For the next build, try a different manufacturer for the PT. This one doesn't seem to suit the circuit too well.

[Bieworm]

Well, 303 is a lot closer to the 300 spec than 289 is. That tells me that's where the PT is probably supposed to be. OTOH, 18W transformers are usually spec'd at 290-0-290 (some as low as 275-0-275) which is probably why your voltages are better the other way.

My suggestion is that since the variance in heater voltage isn't that significant, switch it back unless somebody smarter tells you not to.

For the next build, try a different manufacturer for the PT. This one doesn't seem to suit the circuit too well.

Too late. The parts for the TMB tremolo arrived yesterday and it contains the same 300V HT windings, except this one has only got the 230V option. The secondaries seem better OTOH on 230V.
So how about zenering the 300V's to 290V or add resistors between the 300V taps and the rectifier?

Also noticed that you use a 500K linear vol pot while the Standard TMB values a 500K log pot. Having a log pot in my classic has always made me wonder why it's log. It's nearly an on-off switch like this. If you want to play quiet with the log pot you need to tweak between zero and 0.5. Linear makes more sense

[JMPGuitars]

Too late. The parts for the TMB tremolo arrived yesterday and it contains the same 300V HT windings, except this one has only got the 230V option. The secondaries seem better OTOH on 230V.
So how about zenering the 300V's to 290V or add resistors between the 300V taps and the rectifier?

Also noticed that you use a 500K linear vol pot while the Standard TMB values a 500K log pot. Having a log pot in my classic has always made me wonder why it's log. It's nearly an on-off switch like this. If you want to play quiet with the log pot you need to tweak between zero and 0.5. Linear makes more sense

Oh well, I guess you'll see how the new one reads. You can certainly use whatever safe method you want to drop the B+ and adjust the power tube cathode voltage to 12VDC.

I didn't use a linear volume. A500K is what it says. That's audio or log. B500K would be linear, and C500K would be reverse audio/log. Make sure you're paying attention to the schematic, there are linear pots in there for a few of the others.

Thanks,
Josh

[Bieworm]

Too late. The parts for the TMB tremolo arrived yesterday and it contains the same 300V HT windings, except this one has only got the 230V option. The secondaries seem better OTOH on 230V.
So how about zenering the 300V's to 290V or add resistors between the 300V taps and the rectifier?

Also noticed that you use a 500K linear vol pot while the Standard TMB values a 500K log pot. Having a log pot in my classic has always made me wonder why it's log. It's nearly an on-off switch like this. If you want to play quiet with the log pot you need to tweak between zero and 0.5. Linear makes more sense

Oh well, I guess you'll see how the new one reads. You can certainly use whatever safe method you want to drop the B+ and adjust the power tube cathode voltage to 12VDC.

I didn't use a linear volume. A500K is what it says. That's audio or log. B500K would be linear, and C500K would be reverse audio/log. Make sure you're paying attention to the schematic, there are linear pots in there for a few of the others.

Thanks,
Josh

Ok. I think I'll start with a 150R resistor instead of a 100R on the rectifier on the TMB tremolo design.
Sidenote : I find it really hard to wire the heaters. 2 wires combined are a little too thick for the holes in the lugs. I put 1 wire through and twist the other around the one.

[JMPGuitars]

Ok. I think I'll start with a 150R resistor instead of a 100R on the rectifier on the TMB tremolo design.
Sidenote : I find it really hard to wire the heaters. 2 wires combined are a little too thick for the holes in the lugs. I put 1 wire through and twist the other around the one.

Stop it. That's no good. What gauge wire are you using for the heaters? What brand/type of sockets?

[Bieworm]

Ok. I think I'll start with a 150R resistor instead of a 100R on the rectifier on the TMB tremolo design.
Sidenote : I find it really hard to wire the heaters. 2 wires combined are a little too thick for the holes in the lugs. I put 1 wire through and twist the other around the one.

Stop it. That's no good. What gauge wire are you using for the heaters? What brand/type of sockets?

Don't know the brand. No beltons , but ceramic sockets. The holes are smaller. Same sockets as the previous build and same wire.. 18 gauge.
Don't worry, their pretty fixed and in the same solder

[JMPGuitars]

Don't know the brand. No beltons , but ceramic sockets. The holes are smaller. Same sockets as the previous build and same wire.. 18 gauge.
Don't worry, their pretty fixed and in the same solder

You don't need 18AWG. I usually use 20AWG pre-tinned/bonded wire. Marshall usually uses 22AWG. This is why you have trouble with the heaters.

I ONLY use 18AWG wire for speakers, and the Mains connections including the power switch, and PT connections to the mains. Everything else is 20AWG. I would use 22AWG too if I ever find a brand I like.

With those sockets I would use 22AWG. I don't bother with ceramic. Ceramic can be really good or really bad, and also can be inconsistent. I have no issues with consistency or quality with the Beltons.

Thanks,
Josh

[Bieworm]

Don't know the brand. No beltons , but ceramic sockets. The holes are smaller. Same sockets as the previous build and same wire.. 18 gauge.
Don't worry, their pretty fixed and in the same solder

I looked it up. Tis 1mm2 wire, so that's .78mm diameter ...that corresponds with 20AWG
You don't need 18AWG. I usually use 20AWG pre-tinned/bonded wire. Marshall usually uses 22AWG. This is why you have trouble with the heaters.

I ONLY use 18AWG wire for speakers, and the Mains connections including the power switch, and PT connections to the mains. Everything else is 20AWG. I would use 22AWG too if I ever find a brand I like.

With those sockets I would use 22AWG. I don't bother with ceramic. Ceramic can be really good or really bad, and also can be inconsistent. I have no issues with consistency or quality with the Beltons.

Thanks,
Josh

I thought it had to be that wire. They sold it on the first build kit as to use wire.
Shoot!!!
I'll give it a shot like this. If there are problems I will change that. And in the meantime I will order 20 guage just in case.

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Looked it up. I used 1mm2 wire, which is diameter. 78mm, approx. the same as 20AWG

[JMPGuitars]

Looked it up. I used 1mm2 wire, which is diameter. 78mm, approx. the same as 20AWG

There should be writing on the side of the insulation that says what gauge it is.

[Bieworm]

Looked it up. I used 1mm2 wire, which is diameter. 78mm, approx. the same as 20AWG

There should be writing on the side of the insulation that says what gauge it is.

It's 1 square mm. So like 20 AWG, a little less. Somewhere between 20 and 22AWG.

[JMPGuitars]

It's 1 square mm. So like 20 AWG, a little less. Somewhere between 20 and 22AWG.

There's no hard-to-read writing on the insulation? 1mm is probably 18AWG. 0.8mm is more likely 20AWG. But this method isn't as reliable as reading the print on the insulation.

20awg.jpg

[Bieworm]

It's 1 square mm. So like 20 AWG, a little less. Somewhere between 20 and 22AWG.

There's no hard-to-read writing on the insulation? 1mm is probably 18AWG. 0.8mm is more likely 20AWG. But this method isn't as reliable as reading the print on the insulation.

20awg.jpg

I think you're wrong about this one. In Europe we express wire values in sections, meaning the surface of the wire diameter. In the USA the wire is expressed in diameter. Or do you guys mean 20AWG is the surface in square something?
It is doable though, both wires through the hole.

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I combined them like this for the pin 4 and 5 :

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[JMPGuitars]

I think you're wrong about this one. In Europe we express wire values in sections, meaning the surface of the wire diameter. In the USA the wire is expressed in diameter. Or do you guys mean 20AWG is the surface in square something?

I could be, but I dunno. I googled it and those were the numbers reported. I just measured a 20AWG pre-bonded wire and my digital caliper says 0.9mm, which seems consistent with non-bonded 20AWG wire being 0.8mm.

[Bieworm]

I think you're wrong about this one. In Europe we express wire values in sections, meaning the surface of the wire diameter. In the USA the wire is expressed in diameter. Or do you guys mean 20AWG is the surface in square something?

I could be, but I dunno. I googled it and those were the numbers reported. I just measured a 20AWG pre-bonded wire and my digital caliper says 0.9mm, which seems consistent with non-bonded 20AWG wire being 0.8mm.

Ah we'll see how it turns out.
Don't think the wire thickness with that little difference is of influence on the voltages at the heaters. And if it is, it's always an option to change them over to smaller types.

[JMPGuitars]

Ah we'll see how it turns out.
Don't think the wire thickness with that little difference is of influence on the voltages at the heaters. And if it is, it's always an option to change them over to smaller types.

Nothing to do with the voltage. You tested without the tubes, and voltage was insufficient anyway. The gauge part of this conversation is only about making it easier to wire the heaters. As long as the wire you use is rated for the voltage and current going through it, you're good.