ADA MP1 replacing front jack

[rockman627]

So, I bought replacement jacks for the front of my 2 MP1s. I wasn't too confident these were exact replacements. For the most part, these units are easy to work with; when you remove the upper and lower covers, you have access to both sides of the circuit board. But removing/installing a jack needs some movement on the circuit board and that wasn't easy. Fortunately you can remove the mounting screws and the board will move just enough to get the job done.You have to move the board down and away from the front. It took a bit of effort yo remove the solder and get the old jack out, and just as much effort to line the pins up correctly on the new jack. Remember, you just have enough wiggle room to do this.
After a while I moved a pin a little to the left, a little to the right and then it snapped right in. Only one problem: the threads on the jack doesn't go through the front plate.



It seems pretty firm, but is there anything I can do to really secure this jack? ps it does work and doesn't crackle when the plug moves.

[Jazz P Bass]

Without a capture nut the jack will eventually move and possibly break a solder joint.
You could try running some glue around the jack body.

[g1]

If you found the perfect size nut, it would probably self-thread onto the non-threaded portion that is sticking through the panel. Maybe with a large washer.

[Jon Snell]

There is nothing more to it ... fit the correct socket with the correct length shaft.
You will have a broken PCB otherwise.
Glue is NOT an option!

[J M Fahey]

It is WEIRD that your jack shows so much of its collar NON threaded, so it is the wrong type.

A regular Cliff type is threaded all the way

Please show a similar closeup of the one you bought.
Unmounted, so as to see its collar.

Hope you bought more than one

Worst case link to its supplier page.

[Tom Phillips]

...removing/installing a jack needs some movement on the circuit board and that wasn't easy...

I'm just curious about the limited access that you described indicating that the PCB could barely be moved enough to replace the jack. The photo you posted looks like the front panel can be unscrewed from the side panels. Is that not the case? If so, then that would make the jack replacement easier when you find a jack with sufficient thread length.

[rockman627]

I would have liked to have the exact jack replacement, but everything I read on this issue says the jacks were available from a place in Germany but they ran out and is now unavailable. It is suggested to use a regular switchcraft and do some mod to run wires to the line level input located in the rear. I was ready to do this when I saw that amprepairparts.com offered a replacement jack. This seemed a better way, but it concerned me that no one talked about there being a new jack that could be used. Hence my lack of confidence.

When I get home from work, I'll get some pictures of the old and new jacks.

[rockman627]

Damn, I just saw a video by The Guitologist on YouTube. I don't know why it didn't come up on previous searches, but he says he fixed his input jack problem by reaching inside with tweezer and bending the blades to make good contact. That sounds pretty easy and I will try that when I get home.

[rockman627]

Here is a comparison of the old and new jacks

As you can see, the threads on the new jack does not come out to the edge.

But I think I will try this:

It is a nut from an AC30. I had to slightly widen it with a dremel, but it is on there firmly, and I will test it to make sure most cords will make good contact. If so , I will glue it. And truthfully, if a solder joint loosens, for me it is not critical. Touching up a solder joint is as easy as removing the bottom cover and start soldering.

But for my 2nd unit, I will try to address the existing jack as per 7:43 of this video
https://www.youtube.com/watch?v=QoS8nnIa0_I
If that doesn't work and I have to replace it I will see if removing those screws gets the front plate off.

But I really wish someone would explain to me why you can't get an appropriate Switchcraft jack and wire straight to the PCB. I've done this with Fender Hot Rods and I think it's a great solution.

[Greg Robinson]

But I really wish someone would explain to me why you can't get an appropriate Switchcraft jack and wire straight to the PCB. I've done this with Fender Hot Rods and I think it's a great solution.

You can, and in fact ADA did just that on later versions. You just need to make sure to use shoulder washers to avoid ground loops (same as with the Hot Rod series).

[rockman627]

Where were you when I needed you? Everywhere I looked implied there was something special about the original jack. Can you point to a link? I guess I would have to figure out where tip sleeve and ground go.

[g1]

You can, and in fact ADA did just that on later versions. You just need to make sure to use shoulder washers to avoid ground loops (same as with the Hot Rod series).

pg.6 of the pdf linked shows the original front jack arrangement. http://adadepot.com/mods/ADA_MP-1_v1...ersion_Mod.pdf

and relevant schematics here: http://adadepot.com/mods/ada_mp1a/ADAMP1pre.jpg
and here: http://adadepot.com/mods/ada_mp1b/ADAMP1jck.jpg

[Greg Robinson]

See pictures in this thread on The Gear Page

[Greg Robinson]

BTW, I only took a brief look at the schematics G1 shared above, but I believe a Switchcraft 13A transfer jack can be made to work.
You'd also want fibre insulating washers, one shoulder washer, and one plain.

EDIT: had a chance to look closer at the schems above, the Switchcraft can be made to work, but only with the high-input-impedance rear input jack mod, which is probably preferable anyway. See the documents G1 previously linked.

[J M Fahey]

I´d mount there a regular Cliff type jack such as the one in my picture, *maybe* you must *slightly* enlarge the panel hole, no big deal, and not even try to direct mount it on the PCB
Simply mount it with legs pointing sideways or up (like a helpless cockroach on its back) and wire them to matching holes.on PCB.