SVT-CL 4-pin XLR for Balanced Out?

[Vermouth]

The XLR jack in my SVT-CL was bad and I traced the problem to broken solder joints under it.

The original is a plastic 3-pin jack. I have a metal Neutrik 4-pin jack, but I want to make sure this is ok to use as a replacement? The PCB does have 4 traces for a jack exactly like this, will it be ok? Would there be any issue with its shield grounding to the chassis?

 

[agedhorse]

Mechanical dimensions and orientation are EVERYTHING when it comes to substituting jacks. There are a lot of jacks that look the same but when you start looking at the details they are completely different. I suspect that you will find the same issues in your case. Also, you do not want to use the 4th pin in this case because that bonds the shell to the circuit ground and is generally not done (and can cause ground loop issues when the grounding scheme is not designed to account for this). If the original manufacturer did not use the pin, then do not.

Why not re-use the old jack? It looks like the screws were loose or the amp fell on the connector while the plug was inserted. If this is the case, you want to be sure the sheet metal is absolutely flat or things will continue to break.

This is not an uncommon failure for all types of products manufactured using single sided PCBs and unplated holes, the reason why much of the industry has generally migrated to the double sided PTH (plated through hole) process which is much more robust and reliable.

 

[Vermouth]

That is extremely helpful, thank you. I will just reflow the original.

 

[agedhorse]

That is extremely helpful, thank you. I will just reflow the original.

Use fresh solder w/ flux core.

 

[WRM]

Use fresh solder w/ flux core.

Yes! We found out that solder has an expiration date during one of our audits! Flux does, too.

My only experience with XLR4 is through Am Radio, and it seemed like most XLR4 Mics are used with transmit footswitches, but I could see folks using XLR4 for other purposes, too. It also seemed like XLR3 and XLR4 do not place nice with each other. As mentioned above, if it has XLR3, keep it XLR3.

Cheers,

 

[agedhorse]

The 4th terminal isn't a pin, it's a chassis ground bonding that's not usually used in our industry.

 

[Vermouth]

Could you use an XLR4 in this case if the shield ground pin was wired to an on/off switch? And, is that the same as a ground lift switch? I'm sticking with the original 3-pin, just asking out of curiosity since i have a pro's ear here.

 

[WRM]

@agedhorse Exactly - quite possibly used for different purposes in different industries. I suspect, Heil Sound uses that "extra lead(?)" in XLR4 for a Mic switch? That's the only reason that I can think of for using XLR4 Mic/cables/FS (1/4" TS) and the Kenwood 8-pin "adapter" cable? I much prefer XLR3.


Cheers,

(Edited to add) P.S. It has to be for the footswitch, because the Mic also has a PTT button, and both work (momentary on).

 

[agedhorse]

Note that we are talking about 2 different things here.

A 4 pin XLR has 4 interconnection pins, this is a 3 pin XLR with a chassis bond terminal. Different grounding schemes use the chassis bond differently.

 

[Vermouth]

Ah, yes, my question regarding a chassis-ground lift switch was regarding a 3-pin XLR with the chassis bond.

 

[agedhorse]

Generally the chassis bond and circuit/audio ground occur at only one place on a device, and in many cases it’s not at the jack. This is the case with the amp in the original post.

Ground lifting is usually done by opening pin 1, but this too is not an absolute as there are many ways to effect ground lifting within the context of what ground really represents.

Ground is not a single, unambiguous entity but can be different everywhere in a circuit and at different frequencies. It a VERY complicated subject with text books written on this single topic.