Two-Rock TS1 / ELI Ground Loop Hum nightmare

[martin manning]

Hum eliminated!

Where was it?

[Stevem]

Glad to hear you got your answer.

[Rollylama]

Hum eliminated! Next is converting the heaters to DC. Thanks so much to all and especially Steve for suggesting this test with the lanternIMG_5951.jpeg battery.

How did you fix it? I’ve tried 4 ELI units with my Type 3 and all of them did the exact same thing. One was sent to TR and they just swapped it out with a new one that did the same thing.

[Rollylama]

Glad to hear you got your answer.

Any idea what it was?

[johnnyreece]

I take the response to mean that using the lantern battery solved the issue.

[Rollylama]

I take the response to mean that using the lantern battery solved the issue.

It appears to have helped identify the problem but I can’t imagine he has a lantern battery sitting on top of his amp, lol.

[johnnyreece]

I take the response to mean that using the lantern battery solved the issue.

It appears to have helped identify the problem but I can’t imagine he has a lantern battery sitting on top of his amp, lol.

The next sentence was that he was converting the heaters to DC. So, maybe a bit preemptive to say that it's fixed. Maybe more accurate to say that the problem was identified. Although, OP is welcome to clarify what they said.

[Rollylama]

I take the response to mean that using the lantern battery solved the issue.

It appears to have helped identify the problem but I can’t imagine he has a lantern battery sitting on top of his amp, lol.

The next sentence was that he was converting the heaters to DC. So, maybe a bit preemptive to say that it's fixed. Maybe more accurate to say that the problem was identified. Although, OP is welcome to clarify what they said.

I hope he pops in. I’ve had trouble with multiple units and have a couple of friends experiencing the same thing with Bludos and Brunos….

I even had Jason from TR on FaceTime for a while doing all kinds of troubleshooting and nothing was solved.

[Stevem]

Send the OP a private message to ask this.

[R.G.]

I would like to see the final resolution too. If it is something that isn't covered in "Guitar Amp Wiring Notes" ...

https://www.dropbox.com/scl/fi/ywf5o2fp ... cg34v&dl=0

... I would like to put it in there.

[Rollylama]

Guys, I'm trying to understand why Dumble with his original lator used the half wave rectifier and not a full wave bridge as this method is quieter?

In this one instance, AI was not hallucinating. The difference between half wave and full wave rectification is that the charging pulse to the filter capacitor come twice as frequently. For math reasons, this means you can get the same ripple voltage for half the capacitance, or half the ripple voltage for the same capacitance. This trade off generally means that designers use full wave except for three reasons:
1. The amount of power used is quite small, and the cost of a bigger filter capacitor is not a limitation.
2. The circuit grounding is critical; full wave bridges necessarily mean that the transformer secondary before the rectifiers cannot be connected to signal ground.
3. Economy (that is, being cheap) in that you can buy three fewer diodes.

I don't know why the designers used half wave. Presumably they thought it was enough.

The OP has bailed. Do you think the fix was converting the rectifier to full wave? Or did he somehow mod his amp to power the ELI? So many deleted posts….

I’m not a tech and don’t pretend to be one but if I can figure out whatever will stop it I’m happy to pay someone to do it.

[R.G.]

The OP has bailed. Do you think the fix was converting the rectifier to full wave? Or did he somehow mod his amp to power the ELI? So many deleted posts….

I’m not a tech and don’t pretend to be one but if I can figure out whatever will stop it I’m happy to pay someone to do it.

I can't figure out what he did, and can only guess at why he felt he had to remove so much of his posting. Maybe he was embarrassed at them - who knows?

My best guess is that powering the heaters from DC turned up some previously unsuspected wiring error or wire routing error and he then fixed that. It's a raw guess based on what didn't fix it. If you have one that is having similar problems, maybe it's a same/similar flaw in the design or manufacture. I wish I could help more than this.

[Rollylama]

The OP has bailed. Do you think the fix was converting the rectifier to full wave? Or did he somehow mod his amp to power the ELI? So many deleted posts….

I’m not a tech and don’t pretend to be one but if I can figure out whatever will stop it I’m happy to pay someone to do it.

I can't figure out what he did, and can only guess at why he felt he had to remove so much of his posting. Maybe he was embarrassed at them - who knows?

My best guess is that powering the heaters from DC turned up some previously unsuspected wiring error or wire routing error and he then fixed that. It's a raw guess based on what didn't fix it. If you have one that is having similar problems, maybe it's a same/similar flaw in the design or manufacture. I wish I could help more than this.

Thanks for the feedback. I know of 6 of them that do the same thing so there’s definitely something up with the design…maybe a side effect of trying to cram it all into such a small box?

[Stevem]

I just had the time to read back thru this whole string and it was the powering of the filament with DC that killed the hum in the units output.

So he either in the end converted the units ac filament power to dc ( plenty of room for that in there)

Or he put in a jack in both his amp and the unit to bring in his amps clean filament voltage to run the unit on I don’t know which way he ended up going with.

I wonder if he is going to now offer a mod kit for these units and that’s why he has removed so many of his post here and also not responded to any PM’s.

With the cure now known there are numerous folks on this site who could do this mod on these units, I would offer you such if it where not for having more then I can chew right now for likely 2 months.

[R.G.]

In any case, it is likely that anything from extra-careful, perhaps shielded wiring on the heaters, or a small onboard rectifier/filter setup could fix it. Sad really - it's likely a design flaw where the designer was not sufficiently paranoid on what people might hook up and didn't get a chance to test it widely.

But yeah someone who pumps the forum for a solution then goes dark could also be developing a mod kit to make mega-bucks (... ...) . Or maybe the maker of the widgie got legal on him, something.