C-lator hum

[ynor]

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.

Can a faulty PT unit or a badly designed PT leak more flux than the best ones? Does the end bells have any part in this?

[ynor]

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

Will try and report

[ynor]

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.

Mine was pretty much the same, except the transformer location and missing bells.

All jacks, pots and switches are connected to ground as you state in (2). Will however double check that they make physical contact directly to the chassis and not just by wire. I use a Mogami shielded cable from C-lator to amp, and have tried other cables as well (3). And all chassis grounds have washers as you state in (5).

[martin manning]

Can a faulty PT unit or a badly designed PT leak more flux than the best ones? Does the end bells have any part in this?

Definitely. The shape of the EI core is pretty standard, but inferior material, core construction details, and the winding pattern will affect the leakage. I believe enclosing the transformer helps contain the magnetic flux.

[ynor]

I have been corresponding with Nik, who btw is extremely helpful and service minded towards his customers. However we've progressed far beyond that correspondation in troubleshooting here. He can offer me a good deal on Mercury Magnetics. I'm having some troubles with the PT on my second hand OTS as well, so I guess I order a new full set of XT and choke for the OTS and the C-lator from MM. They are expensive, but if they are the safest bet I could justify the extra costs for that peace of mind.

[rogb]

FWIW I built my Dlator with a transformer I got from Nik many years ago. Not sure of the quality, but still working! In my various iterations of Dlator over 12-14 years, it has always been externally mounted on the rear panel as per the Dumble ones. The only problems I've had has been with switching jacks. It has always been hum free.
If you get a new PT, maybe mount it on the rear panel to keep it away from signal carrying parts?

[martin manning]

I think C-tone's transformers are at least variable in quality. No doubt low cost is a factor there. The price/performance of MM transformers is debatable, but if you can get them at a good price, then it's a probably a good move, and it will increase the value of your gear. Does Mercury have a C-lator PT that fits inside the chassis, or would you have to convert to outside rear mount?

[ynor]

Does Mercury have a C-lator PT that fits inside the chassis, or would you have to convert to outside rear mount?

I'm not sure. Will have to check that out.

I think the next move will be to disconnect the secondary side of the PT and note the results. Then disconnect the PT completely, move it out of the chassis, extending every lead and putting the PT 30 cm away from the chassis. If it's flux, that should be too far away to interfere with anything in the chassis. Correct? Will I need to connect the feet of the PT to chassis ground?

Will also double check that the pots have connections directly to the chassis and not only grounded by the ground bus and wire to signal ground.

[martin manning]

Sounds good. The first thing is to see if there is hum with only the PT primary connected. If so that means the source is the PT. Relocating the PT outside the chassis and connecting it with temporary leads would be the next step to see if position or electrical contact with the chassis is the path.

You could take the nuts off the controls and look to see if there is good contact between the pot housings and the chassis (i.e. with internal-tooth star washers), but you have already confirmed that there is ~0 ohms resistance between circuit ground and the pot housings. I am not a fan of soldering a bus to the pots to ground the housings. It is generally messy and unnecessary.

[bepone]

Can a faulty PT unit or a badly designed PT leak more flux than the best ones? Does the end bells have any part in this?

yes, flux is leaking around with increased saturation , if is bad designed (too low primary turns)

[bepone]

I have been corresponding with Nik, who btw is extremely helpful and service minded towards his customers. However we've progressed far beyond that correspondation in troubleshooting here. He can offer me a good deal on Mercury Magnetics. I'm having some troubles with the PT on my second hand OTS as well, so I guess I order a new full set of XT and choke for the OTS and the C-lator from MM. They are expensive, but if they are the safest bet I could justify the extra costs for that peace of mind.

Refuse, it is not your problem that designer made bad choices and bad unit, and also you need to pay something additional? Refuse.
Expensive menas nothing for quality it is just price boosted.
In case you need any PT i can search and find something - Norway is in europe (by trade if i remember), any EU shop should be good, and also my local winder can send it there.

[bepone]

@ynor
For this shame and troubles and specially a waste a lot of extremenly expensive free time, you should receive new Dumblelator (-working-) for free from the manufacturer!

[rogb]

I have been corresponding with Nik, who btw is extremely helpful and service minded towards his customers. However we've progressed far beyond that correspondation in troubleshooting here. He can offer me a good deal on Mercury Magnetics. I'm having some troubles with the PT on my second hand OTS as well, so I guess I order a new full set of XT and choke for the OTS and the C-lator from MM. They are expensive, but if they are the safest bet I could justify the extra costs for that peace of mind.

Given that Classictone has now gone, you will have no trouble with Twin 100w or Bassman 50 w transformers from Hammond and you can order them from Mouser.

50w Bassman

https://no.mouser.com/ProductDetail/Ham ... 3P7Q%3D%3D

Choke
https://no.mouser.com/ProductDetail/Ham ... Vbqw%3D%3D

[ynor]

@ynor
For this shame and troubles and specially a waste a lot of extremenly expensive free time, you should receive new Dumblelator (-working-) for free from the manufacturer!

I agree. I'll address that to the manufacturer if it turns out that it needs replacement parts and is not easily cured by something small that's easily resolved.

Although I'm getting frustrated and would rather spend time playing that thing, messing around inside this gear is kind of fun too. Still.

[ynor]

Given that Classictone has now gone, you will have no trouble with Twin 100w or Bassman 50 w transformers from Hammond and you can order them from Mouser

Those are cheaper yes, but the prices I got on the MMs are not that much more and are direct dropins without the need to drill new holes in the chassis. But are these Hammonds just as good (and safe from vibrating laminates) as the MMs?