PCB mounting of XLR/TS jacks, best practices?

[Elegost]

My designs to date have used jacks that were handwired to the pcb board. However, I just built a switching unit that has 12 jacks and the resulting rats nest has me thinking about using pcb-mounted jacks in the future. Are there best practices for mounting (a large number of) jacks on a PCB? Should the PCB be free-floating so as not to create tension between the pcb mounting and the jack mounting? Or is it ok to mount jacks on a pcb that is itself mounted? I can find examples of both techniques in gutshots of commercial gear. Or should i stop overthinking this

 

[NOON]

Best not to have jack sockets mounted on a board that is secured to the chassis if possible. Cheap and simple to assemble which is why it's commonly used but you will eventually have cracked solder joins and it's harder to work out the hole positions in 3D when DIYing. I usually have a board that holds the sockets and maybe a few light components and run a connector to the main board.

 

[user 37518]

Best not to have jack sockets mounted on a board that is secured to the chassis if possible. Cheap and simple to assemble which is why it's commonly used but you will eventually have cracked solder joins and it's harder to work out the hole positions in 3D when DIYing. I usually have a board that holds the sockets and maybe a few light components and run a connector to the main board.

The Neutrik NRJ jacks are extremely rugged, they have 6 very thick pins plus a plastic stub which fits into the PCB, I would definitely bet money that there wont be any cracked joints.

 

[JohnRoberts]

Well designed jacks for PCB mount will include mechanical stress relief (screws or plastic bosses) so plugging and unplugging jacks into them do not fatigue solder joints. There are multiple different approaches for grabbing chassis ground connections. Both Neutrik and Switchcraft make serviceable jacks, we've used truckloads of both brands (at Peavey).

JR

 

[Newmarket]

Or is it ok to mount jacks on a pcb that is itself mounted? I can find examples of both techniques in gutshots of commercial gear.

As pointed out above a good connector design should minimise problems with the connector itself.
But you can have problems with the pcb if it is "hard fixed" to the chassis eg with pcb standoffs that put strain on it due to mechanical tolerances.
Way around this - first fix via the jack sockets. Then fix to the pcb support etc. in the usual way but with the pcb mounting hole(s) being large enough to allow for any tolerance required, So basically the pcb 'sits' as defined by the jack fixings and can then be fixed in that position.
It helps if the jacks themselves are properly aligned on the pcb. So not having pcb hole sizes too large for the jacks is useful here - and maybe using a jack with kinked pins for positive location and also any mechanical fixing elements such as the 'stub' mentioned above.

 

[Matador]

Both Neutrik and Switchcraft make serviceable jacks, we've used truckloads of both brands (at Peavey).

I've repaired boatloads of Peavey guitar amps with broken/cracked PCB connections at the input jacks. I think 1/4" and XLR connections are special due to the torque one can apply to the plug shell itself. It's almost impossible to pull a connection straight out, and 1/4" connections are subject to constant flexing (especially input jacks). Pots are probably different, because they are only subject to rotational forces which are easier to absorb through the face plate. PCB mounted jacks are also a royal pain to service, often requiring complete disassembly of the device in order to replace the part (I'm looking at you again, Peavey).

I understand that manufacturers building thousands of units don't want to take the labor hit running leads between front panel components and PCB's, but for DIY, I can't see an excuse to do it any other way.

 

[JohnRoberts]

I've repaired boatloads of Peavey guitar amps with broken/cracked PCB connections at the input jacks. I think 1/4" and XLR connections are special due to the torque one can apply to the plug shell itself. It's almost impossible to pull a connection straight out, and 1/4" connections are subject to constant flexing (especially input jacks). Pots are probably different, because they are only subject to rotational forces which are easier to absorb through the face plate. PCB mounted jacks are also a royal pain to service, often requiring complete disassembly of the device in order to replace the part (I'm looking at you again, Peavey).

I've been outside the walls since the turn of the century... I don't recall a Peavey customer ever saying they wished the SKUs cost more.

I understand that manufacturers building thousands of units don't want to take the labor hit running leads between front panel components and PCB's, but for DIY, I can't see an excuse to do it any other way.

It is basically a cost issue, but in addition to the labor to solder individual leads p to p, that process introduces another opportunity for factory line workers to make mistakes, and/or lower reliability connections.

JR

PS: I won't bore you with TMI about bad connectors, we suffered one batch of PC mount female Neutrik XLRs that wouldn't release. That took several months to correct. Neutrik had to retool their connector locking mechanism.

 

[Newmarket]

I've repaired boatloads of Peavey guitar amps with broken/cracked PCB connections at the input jacks.

I daresay that's annoying for users but it also likely reflects the large number of Peavey amps sold.
I'm in UK. Back in the 90s their Guitar Amps were very popular for those not touting Marshall etc.
The guitarist in a band where I played bass had a 60 Watt 1x12 Combo and it pretty much covered all the bases. Their bass kit (and esp Black Widow 1x15 speakers) were also notably popular.
Much less so now - their place has probably been taken by Blackstar or others.

I think 1/4" and XLR connections are special due to the torque one can apply to the plug shell itself. It's almost impossible to pull a connection straight out, and 1/4" connections are subject to constant flexing (especially input jacks).

Yes - i wouldn't say "almost impossible" in most cases but it does happen. It always seems odd.
I'm not sure if it relates to the mating of connectors from different manufacturers - but there is always a question of metric/imperial conversion tolerances.
Sometimes it just feels like the crisp packet thing where it somehow doesn't pull open however hard you pull. Then you move fingers fractionally and there's no problem ! (I claim my prize for "Analogy of the Day" )

 

[FIX]

I use the Neutrik A or AA series, soldered to the PCB, and I float the rear of the board and don't start hard mounting it until I'm about 3" away. This allows the board to give a little. Never had a single XLR fail, since the 90's. Screwed into the panel with the correct screws.

 

[swpaskett]

Always use thru-hole connectors; never SMT.

 

[Newmarket]

I use the Neutrik A or AA series, soldered to the PCB, and I float the rear of the board and don't start hard mounting it until I'm about 3" away. This allows the board to give a little. Never had a single XLR fail, since the 90's. Screwed into the panel with the correct screws.

I think it's not do much an issue with XLRs. Jack plugs can exert greater force due to their length an subsequent possible torque.

 

[JohnRoberts]

I think it's not do much an issue with XLRs. Jack plugs can exert greater force due to their length an subsequent possible torque.

My single worst jack problem was with an XLR where the locking mechanism wouldn't release, but I saw problems with all kinds of jacks (switching jacks were another PIA).

JR

 

[Speedskater]

The problem with mounting XLR jacks on a PC board is Pin #1. Pin #1 needs to be connected to the chassis near the connector.
This is a Jim Brown, AES pet peeve.

 

[Newmarket]

The problem with mounting XLR jacks on a PC board is Pin #1. Pin #1 needs to be connected to the chassis near the connector.
This is a Jim Brown, AES pet peeve.

The two things are not mutually exclusive. See Neutrik PCB types that connect P1 direct to chassis.

 

[JohnRoberts]

The problem with mounting XLR jacks on a PC board is Pin #1. Pin #1 needs to be connected to the chassis near the connector.
This is a Jim Brown, AES pet peeve.

I recall neutrik having a ground lead that would pierce through paint or powder coat to insure a bond to chassis metal.

JR

 

[Newmarket]

I recall neutrik having a ground lead that would pierce through paint or powder coat to insure a bond to chassis metal.

JR

Yes. I used that on a commercial product.

 

[gyraf]

I recall neutrik having a ground lead that would pierce through paint or powder coat to insure a bond to chassis metal.

JR

Yes, I think this goes for the Neutrik connectors with a -1 in the model name - like e.g "NC3FBH1" or "NC3FP-B-1" - these all have pin1 connected to chassis

 

[Monte McGuire]

The pin1 connection on that connector is also a good way of bringing chassis into the PCB - useful for RF bypass capacitor grounding.

 

[Speedskater]

The two things are not mutually exclusive. See Neutrik PCB types that connect P1 direct to chassis.

Very true but not very common in mass produced (cost reduced) products

 

[JohnRoberts]

Very true but not very common in mass produced (cost reduced) products

In my 15 years working for Peavey I found that product improvements that don't cost more to manufacture were always a good thing. I recall meeting with the owner of Neutrik at multiple Frankfurt musik messes where we could work on new connector designs. When you buy connectors by the truckload (boatload) the makers are very accommodating.

I was impressed with Neutrik's ability to solve problems, cost effectively.

JR