C-lator hum

[ynor]

What are the chassis and lid made of? Are they both the same material?

Yes

[ynor]

The chassis and lid are made of steel. This could explain vibrations. Especially when it lays lose on top of the chassis.

The transformer in the enclosure was probably not the best idea Nik had. I dont understand it either because it looks like the exact same PT, except the bell cover.

The PT also vibrates when the kid is screwed tight to the chassis, but yes, it vibrates less when tightened. But the PT doesn't vibrate at all once the lid is completely removed. It is then silent, but hum is still present. When the lid is moving towards the chassis, hum increases. And when lid is mounted, the PT vibrates as well together with the hum.

I also have observed that the PT is the same as before, but mounted inside with different orientation (90 degrees rotated counter clockwise and close to rectifier/filter circuit) and without the bell cover. I don't know how much the bell cover shields the magnetic flux, and if that might be part of the equation?

[ynor]

Can I just check: Are you saying here that having the device main power switch set to off (I.e. primary PT loop is broken) you *still* get a hum, albeit lesser, that only stops when the IEC cord is removed?

Can you please retest that, ensuring that the caps are discharged?

Correct. But it is a different hum with higher harmonics if I recall correctly. I did not discharge the caps after powering off but can try that and report back. It is safe to discharge those caps with power off and IEC cord still plugged in, yes?

Part of this hum was removed by lifting the ground (safety ground wire to chassis removed).

[ynor]

. Double post...

[bepone]

This transformer looks like is making magnetic short turn with the chassis when lid closed, going to saturation and spreading the flux around. This can be check with the power consumption.. if is like this, preamp will start to draw more current when lid is closed, and start to vibrates. This PT i would change immediately today .

There is simple solution with 2 transformers 230V-12V like here:
https://www.valvewizard.co.uk/curvetracer.html


Lets proceed with permanent lid open from now on, to avoid confusion.

Lets go on (very easy and fast to do):

Are the back of the pots grounded finally?
Is it 100R reference for the heater moved to preamp stage (remove from pcb 2 resistors)

Results?

[bepone]

Also pointing the grounds in the c-lator ,for sure are wrongly connected. All the signal and all the "grounds" in clator must be connected without the use of chassis.

My recommendation, chassis use for IEC gnd only, not for the signal, signal gnd must have bigger path to the Earth gnd, per example lift signal ground in c-lator via 10R 3W to the chassis. Per example all the grounds are going to the last filter capacitor, nothing on the chassis, and from there is only connection to the chassis via 10R-5W. Thats it.

People using chassis wrongly will introduce all kind of problems, SPECIALLY in those multi unit systems. Chassis is not here to pass the signal through.

[ynor]

This transformer looks like is making magnetic short turn with the chassis when lid closed, going to saturation and spreading the flux around. This can be check with the power consumption.. if is like this, preamp will start to draw more current when lid is closed, and start to vibrates. This PT i would change immediately today .

There is simple solution with 2 transformers 230V-12V like here:
https://www.valvewizard.co.uk/curvetracer.html


Lets proceed with permanent lid open from now on, to avoid confusion.

Lets go on (very easy and fast to do):

Are the back of the pots grounded finally?
Is it 100R reference for the heater moved to preamp stage (remove from pcb 2 resistors)

Results?

Thanks! Will continue with the lid open from now. Have not had the time to try moving the ground for the 100R to signal ground yet, but will do that.

I also observe from the layout that the rectifier is connected to the same ground as the 47 uF.

I can confirm that the back of the pots are grounded. Not sure if it makes direct contact with the chassis, but there is 0 Ohm between the pots chassis and signal ground. The ground lug is connected to a wire bus that is connected to signal ground.

[bepone]

this is all wrong, electrolityc caps cannot go to the chassis, specially first one

pls give me picture pointing in this direction to see pcb traces

pic.jpg

[ynor]

Need to make sure the pots make direct contact with chassis disregarding the ground wiring shown here?

20240319_192512.jpg

[bepone]

Need to make sure the pots make direct contact with chassis disregarding the ground wiring shown here?

20240319_192512.jpg

connect them to this buss bar, for the moment leaveother groundings untouched, , scratch back of the pots and connect all 3 here and report the hum situation

[bepone]

see here back of the pots, one wire like this
https://www.sweetwater.com/insync/media ... -photo.jpg

[bepone]

100R reference from heaters, taken from PCB connect also to this buss ground (disconnect 100R x2 from the supply side)

[Richard1001]

I have the exact same Ceriatone C'lator with five differences:

1. The transformer is outside the chassis.
2. All metal parts are have reference ground to chassis (pots, switches etc.)
3. High quality shielded cable.(Both inside the unit and to connect the unit to an amp)
4. Two chassis grounds. (1= IEC + first capacitors of the powersupply / heater; 2 = Signal + both 33uf powersupply capacitors)
5. All chassis grounds have washers with teeth that grip into the metal and the paint is removed to ensure good connection.

I use the C'lator for practice, (very) loud stage volume and on different amps. No hum or noise, no ground loops, no problems.

[bepone]

me also thinks that transformer is major problem, proximity to the other circuits , then also missing metal parts groundings, lets see what will be after this action

[martin manning]

I have the exact same Ceriatone C'lator with five differences:
1. The transformer is outside the chassis.
2. All metal parts are have reference ground to chassis (pots, switches etc.)
3. High quality shielded cable.(Both inside the unit and to connect the unit to an amp)
4. Two chassis grounds. (1= IEC + first capacitors of the powersupply / heater; 2 = Signal + both 33uf powersupply capacitors)
5. All chassis grounds have washers with teeth that grip into the metal and the paint is removed to ensure good connection.

I use the C'lator for practice, (very) loud stage volume and on different amps. No hum or noise, no ground loops, no problems.

My D'lator has the same ground scheme, except the pot housings are grounded via star washers on the bushings. The rear panel jacks are not isolated, so there is a second signal ground here. The power transformer is inside the chassis and fully enclosed (with end bells). As you can see, the small size places everything in very close proximity.

Dlator_inside_rear_mpm.JPG