Input Jack ground to chassis query

[Steve Blackdog]

hello all
Am I right in thinking this schematic shows that the input Jack is meant to be grounded to the chassis? Or more to the point, the connection on the far left to Jk1 which is separate from the connection to the sleeve of the socket, is meant to attach to a washer connected to the chassis ground?

The connection from mains earth to the pcb goes first to the chassis and then onto the board via opposing diodes, resistor and cap in parallel.

This is my almost finished Blackstar HT60 soloist project.

Any thoughts?

cheers

steve

[xtian]

No, this schematic shows that the input jack is not directly connected to the chassis, but goes via C501 -- I've never seen a capacitor with three leads like that!

[g1]

No, this schematic shows that the input jack is not directly connected to the chassis, but goes via C501 -- I've never seen a capacitor with three leads like that!

It's strange looking all right. Are the lower 2 legs connected? If so, wouldn't plugging a mono plug into the jack short the ring to the sleeve? Wouldn't that short the sleeve to ground? I guess those lower 2 legs are not connected like I think they are.
I'd like to see the datasheet for that 'capacitor' part.

[Enzo]

Those caps are more common in RF, which is what they are here for, they shunt off any RF.

C501 is a pass through device with a cap to a third leg. Official name? I nave no idea. Pass through cap? Feed through cap? Looks like feed through cap is the term. I have a bunch removed from equipment that are like a standoff, but with the post going all the way through the chassis and insulated from the mount .

When you plug a plain old TS guitar plug into that, the ring contact grounds the sleeve through the C501 pass through. The actual sleeve contact is connected to ground through the capacitance of C501.

The ground in this discussion is circuit common, not chassis/earth. C501 and L1 form an RF filter. Chassis/earth connects to common via the afore-mentioned diodes, cap, and resistor.

[g1]

When you plug a plain old TS guitar plug into that, the ring contact grounds the sleeve through the C501 pass through. The actual sleeve contact is connected to ground through the capacitance of C501.

The pass through is a RF inductor? Otherwise I think it would be pointless to ground the sleeve via a cap if that cap gets shorted out as soon as you plug something in?
And with something plugged in, the cap is now parallel with the inductor?

It would make a lot more sense if they drew that pass through as a coil.

[Enzo]

C501 is just a cap with a wire straight through. L1 is the inductor, one of those dual winding common core deals, the wires are shown running straight through it. I mean both the cap and the coil have pass through conductors.

I am not familiar with a Belton PJ-011, perhaps the sleeve/mount grounds to panel, and somehow this serves a purpose.

[Steve Blackdog]

This is the jack socket. You can see a scorch where it sat on the solder for the “fifth” leg. Nothing connecting it to the sleeve as I can see.

[Steve Blackdog]

So what does c501 connect to? The 4 legs of the mono switched socket are all busy, but the c501 connection is directly below the Jack socket and was “attached” to the plastic with a blob of solder. What does the schematic line to jk1 mean?

by the way, here’s blurb on three legged feed through caps.

[Enzo]

Your pictures render it moot, that is not a TRS jack.

[Steve Blackdog]

Your pictures render it moot, that is not a TRS jack.

No, just sleeve and tip like the schematic. That’s why I thought c501 went to an earth washer.

[Enzo]

Oh jeez, my sincere apology, the schematic is indeed a TS jack, and somehow in my head it became TRS, Sorry.

[Helmholtz]

Schematic shows 5 terminals at input jack. Looks like a TRS jack to me.

[Steve Blackdog]

Schematic shows 5 terminals at input jack. Looks like a TRS jack to me.

But just a TS. I’m really thinking it is another chassis ground.

I have emailed Blackstar for clarification.

[g1]

Whatever it is, it looks like the vias (feed-throughs) came out with it. You will have to verify that traces on top side of board connect to those on bottom side once you replace it.

[Enzo]

If one looks at the schematic the sets of contacts are even labelled T and S, no R.If I had to guess, might the "bushing" contact be one of those washer deals to contact the chassis?