Patch cable problem?

[Andrex88]

Hello everyone, I have a rack that I completed one step at a time, I assembled the patch cables by myself, with the soldering iron I soldered them trying to be careful to make a good solder, the cable and a sc spirit. Since my rack tends to be very noisy during the search for the problem I got the idea to check if by pure chance there were any patch cables that had problems actually many of them oscillate from a few Kohms to a few Mohms, example of measurement to the tester between tip and tip 0 ohm and it is correct between sleeve and sleeve 0 ohm also correct here, but between sleeve and tip some cables measure from a few Kohms to a few Mohms and I don't understand why as they should be two totally separate things and the tester should not measure any resistance between tip and sleeve. Is it possible that the cable is bad? I attach a video. Thank you all

https://www.youtube.com/watch?v=6OEh3xzAMAc

[Helmholtz]

Resistance between inner and outer (shield) conductor should be extremely high. Meter should show O.L.(meaning over meter limit).
No resistance would mean zero Ohm, so just the opposite.

Most cables have a CONDUCTIVE black plastic sheath below the shield. Make sure this is cut back enough so it can't touch the inner conductor-tip connection (e.g. when flexing the cable).

Maybe post a picture.

[Chuck H]

@ Helmholtz:
Any chance a cheap meter or failing meter could be reading the tip to ring capacitance as a partial resistance? I ask because it seems unlikely that all the cables would have the same intermittent shield contact consistently. I would expect a flaw like this to be inconsistent cable to cable.

EDIT: I think it's at least worth checking results with a different meter.

[Andrex88]

@ Helmholtz:
Any chance a cheap meter or failing meter could be reading the tip to ring capacitance as a partial resistance? I ask because it seems unlikely that all the cables would have the same intermittent shield contact consistently. I would expect a flaw like this to be inconsistent cable to cable.

EDIT: I think it's at least worth checking results with a different meter.

not all cables, some mark .OL as it should be, I used two differemt testers, one of good quality and the other not, but the result is the same

[Chuck H]

Just though of something else. Not Andrex88's experience level understand that I mean no offense. Touching the meter probes to the tip and ring on the cables must be done without finger contact or the meter may read a partial resistance through your body.

[Helmholtz]

@ Helmholtz:
Any chance a cheap meter or failing meter could be reading the tip to ring capacitance as a partial resistance? I ask because it seems unlikely that all the cables would have the same intermittent shield contact consistently. I would expect a flaw like this to be inconsistent cable to cable.

Capacitance doesn't show with DC.

I don't see much consistency in the video.

I carefully watched for finger contact, but didn't spot any.

[Tom Phillips]

...I used two different testers, one of good quality and the other not, but the result is the same

It would be an interesting experiment to make the same measurement on some samples of your cable that have not been soldered to connectors. It's a long shot but easy to do.

[Chuck H]

not all cables, some mark .OL as it should be, I used two differemt testers, one of good quality and the other not, but the result is the same

Ah. Ok. Thank you. Then I would proceed as Helmholtz suggested. With metal case, right angle plugs I also add a piece of electrical tape to the inside of the cover plate for good measure.

[Helmholtz]

When a cable always measure O.L. between tip and sleeve, it's good.

When you see a lower resistance, I can't think of an other reason than the conductive sheath or other internal partial short.
Hence picture would help.

[Chuck H]

Capacitance doesn't show with DC.

I don't see much consistency in the video.

I carefully watched for finger contact, but didn't spot any.

I admit that I didn't watch the video. My considerations were based on just the post. And I know that meters use DC to test resistance. I just wondered if some cheap meters or some meter failure might present a small AC artifact causing odd readings. I should have watched the video.

[Andrex88]

Resistance between inner and outer (shield) conductor should extremely high. Meter should show O.L.(meaning over meter limit).
No resistance would mean zero Ohm, so just the opposite.

Most cables have a CONDUCTIVE black plastic sleeve below the shield. Make sure this is cut back enough so it can't touch the inner conductor-tip connection (e.g. when flexing the cable).

Maybe post a picture.

I hadn't considered the black sheath they were my first cables and I didn't think about that detail at all, I actually hadn't cut it and it touched the central pin. Thanks for helping me I learned something new, I've already fixed all the cables but unfortunately the noise remains, maybe I'll take a picture of the connections and the rack but I think it has to do with the rocktron loop8 that generates all that noise.

[Helmholtz]

I just learned a new English word : "sheath" and edited my posts above and replaced sleeve with sheath.
So I'm fine with the result .

[Andrex88]

I don't think it's the right section but I wanted to share with you and listen to your opinion regarding the connections I made if they can make sense, certainly the JMP1 and the 9200 have no problems, it is known that they have a tolerable minimum of natural hiss in fact by connecting them and excluding them from the rest of the rack, you can hear it slightly but it remains slightly, I think the problem is in the rocktron patchmate loop 8, it creates some sort of infernal loop, despite the fact that there is the powerbrite which should act as a stabilizing filter, for a I envy those who are satisfied with only a head and a cabinet, in racks you spend a lot of money to filter noises and you can never eliminate them. I even mounted plastic strips between the rail and each individual module with plastic screws to avoid direct contact with the rails and also horizontally between modules.

[Chuck H]

You're complaint is hiss? I have never heard of, nor do I have any explanation why a "loop hiss" could or would happen. Hum for sure. Hiss is a byproduct of amplification. Gain and thermal properties of components. There are ways to minimize it though. Being fastidious about headroom and clipping levels for signal returns is very important. eg: Any time a signal is lower than what a fed devices input can accurately amplify, that fed device output must now be increased to make up the difference. This added amplification also means added hiss. This is about the only criteria YOU can control, because...

Some device circuits are just poorly considered for noise. Not every design is a peach. Some sound better but hiss more. Some sound like crap and hiss more and some sound great and hiss less, etc. With so many devices using multiple amplification stages and sometimes doing many things signals get buffered and reamplified A LOT in musical instrument circuits. This is a really good reason to keep signal chains as sparse as practical. So...

If you have a device that's hissy on it's own then make sure it's output is as loud as the fed devices input can accurately handle and that the fed device isn't also hissy because that makes bad into worse. Also...

Some opamp devices can get noisy because of failing amplifiers. Replacing them can sometimes quiet things down. So if you have a device that seems to hiss more than it use to or more than users typically report (as mentioned, some circuits are just hissy by design) there's a possibility it needs repair. It's not uncommon for old transistors and opamps to become hissy with age even when they're still working correctly otherwise.

[Andrex88]

yes I did not specify the noise that is heard because unfortunately I find it hard to define it, I am attaching the video where this noise can be heard, as mentioned by connecting the guitar directly to the jmp then the jfx and the 9200 you hear a slight hiss but it is tolerable, not a hum like the one in the video, it seems the problem is created in the rocktron loop. If I then turn on the GK we don't talk about it, it doesn't want anything between the guitar and the GK, otherwise there will be an even more accentuated buzz, I had to exclude it from the chain

https://youtu.be/2jzmzR-WjIc