Ticking sound in tremelo (solved)

[nebukatnessar]

So just a moment ago my 18watt 1974x made sound for the first time.
It almost worked the first time, but I kindof hooked up the speaker jack on the wrong side!
Luckely I did not continue ramming away at full throttle for the first try, so my OT survived running without a load for a few seconds.
After that I found out that I missed 1 b+ connection to the fase inverter and than it worked.

So for a first build I am very pleased at how wel this went.
And I must say, this thing is great! I really love it.

But alas there is a problem. I get a ticking sound in the tremelo. It gets worse at the maximum speed or the mininum intensity.

What could this be? I used this schematic storage/18watt%20Schematic%2008-28-03%20-3.pdf

I have to make 2 notes. The 12ax7's are very used ones that came form my JCM800 and I had laying around.
And I had compromise a resistor value. I did not have the R10 2.2M and I substituted it for a 3.3M

I hope some can help me with this. Because when I play I don't hear it and the trem sounds lush.

[Bieworm]

So just a moment ago my 18watt 1974x made sound for the first time.
It almost worked the first time, but I kindof hooked up the speaker jack on the wrong side!
Luckely I did not continue ramming away at full throttle for the first try, so my OT survived running without a load for a few seconds.
After that I found out that I missed 1 b+ connection to the fase inverter and than it worked.

So for a first build I am very pleased at how wel this went.
And I must say, this thing is great! I really love it.

But alas there is a problem. I get a ticking sound in the tremelo. It gets worse at the maximum speed or the mininum intensity.

What could this be? I used this schematic storage/18watt%20Schematic%2008-28-03%20-3.pdf

I have to make 2 notes. The 12ax7's are very used ones that came form my JCM800 and I had laying around.
And I had compromise a resistor value. I did not have the R10 2.2M and I substituted it for a 3.3M

I hope some can help me with this. Because when I play I don't hear it and the trem sounds lush.

I'd say start with good tubes. The tube for the tremolo is a critical part of the trem working the way it should. And change that resistor too. My gut feeling says it's not that critical, but the value has come from somewhere...
I must say I never had a ticking trem in an 18W..that's more of a disease in optotrem circuits. The whoosh whoosh is more common in 18W amps.
Could also be a lead dress issue though.. chopstick them wires ar the trem.

[nebukatnessar]

I already robbed the JCM800 of its fairly new JJ 12ax7's. None of those fixes it.
I have not yet poked the leads. I will try that.

But my main course of action will be to order the right resistor and the .01 capacitors in the trem circuit. The BOM says they should be disk capacitors, but I used metal film caps.

I'm wondering if that could cause this.

[Daviedawg]

This was a topic a long time back. Not heard of it recently.At the moment I cannot recall the outcome. The schematic is the most used format for the trem version so is well tried and tested including on my own.

This trem form is very sensitive to the individual valve (V3 on your schematic) and the voltage on that half of the 12ax7. But since you have already swapped valves that is less likely to be the case here. My thoughts are that there is an issue with a joint or component so a chopstick of the trem stage would be worthwhile.

Meanwhile if I can find or recall what the previous instance was I will post.

Dd

[nebukatnessar]

I did not find a bad joint with chopsticks.
Is there a voltage table somewhere? E.G. what should be the voltage on that half of the 12ax7?

[Bieworm]

I didn't refer to solder joints rather moving some wires while the ticking sound is audible. See if that affects the noise...

Here's a link to the documents.
viewtopic.php?t=25606

[nebukatnessar]

So yes. Moving the B+ wire going in to pin 1 changes the sound, the intensity changes.
But so does measuring the voltage.

And that seems a little high. When grounding the tremolo I measure 175 volts. When it is on it obviously swings beween 165 and 180.

According to this chart it should swing between 110 and 150.
files/JMPGuitars_18_Watt_Modern_Classic ... _Chart.pdf

The B+ coming from pin 3 of the EZ81 is 338 so that seems to be right on the money.

Since I understand the tremolo is very sensitive about the voltage. I'm now on the path of finding out why this is about 50 volts to high.

[nebukatnessar]

So I reviewed all the parts around the tremolo circuit. And I was kind of pissed of at myself for sodering c7 in such a way that value wasn't facing up. And looking flat over the board to read 0.0047uf.



That's not right. It should be 0.05uf!
I even left the 0.0047 in it and set a 0.047 over it in parallel. This makes the total actually closer and I did not have to remove all the stuff to get to the 0.0047.

Fired it up. Problem gone. By the way the voltage on the trem side of the 12ax7 still measures 175v, but I think it will be alright.

Thanks for all the help!

[Bieworm]

So I reviewed all the parts around the tremolo circuit. And I was kind of pissed of at myself for sodering c7 in such a way that value wasn't facing up. And looking flat over the board to read 0.0047uf.



That's not right. It should be 0.05uf!
I even left the 0.0047 in it and set a 0.047 over it in parallel. This makes the total actually closer and I did not have to remove all the stuff to get to the 0.0047.

Fired it up. Problem gone. By the way the voltage on the trem side of the 12ax7 still measures 175v, but I think it will be alright.

Thanks for all the help!

Thanks for reporting back!

[Daviedawg]

Great. Glad to hear it is working. The plate voltage on that half of the valve on my amp is 189 and has been around that for more than 12 years of regular playing so yours is not out of the way.

Dd