Marshall JH-1 distortion pedal

[pablo2011]

I have been asked to look at a friends Marshall JH-1 'Jackhammer' pedal after he 'dropped it'.

The foot-switch activates the 'active' red LED but as soon as a jack is inserted into the 'In' mono jack socket the light goes out and there is no signal throughput. With foot-switch in the 'off' position the signal bypass works fine.

I have now replaced the mono jack input socket (as it was very worn) and also the DPDT foot-switch but with no change.

Any suggestions greatfully received.

[rowdy_riemer]

Hmm. The opposite should be happening.

[rowdy_riemer]

I've got one of these. I'll try to remember to take it apart and see what I can figure out. It might be a bit, though, because I'm very busy here lately with work and school. I might end up working this weekend, in fact. But I'll try not to forget to check into it, if no one else solves it before I get a chance.

[pablo2011]

Thanks, any ideas would be great.

[J M Fahey]

Check for cracked solder, broken tracks, etc, with a good loupe or 4x reading glasses, under *good* light, because as Rowdy said, the opposite should be happening: receiving power with a plug inserted and turning off when pulled.

[rowdy_riemer]

I noticed on mine that the jack has two switches, a normally open one nearest the opening of the jack, and a normally closed one. On the output jack, they are both normally closed. Of course, inserting the male jack from the cable reverses their open/close status. What kind of switches are on the replacement jack?

[J M Fahey]

Interesting, that might be the key to the problem.
Worst case, if the original jack is unavailable, he might add a small switch somewhere to turn it on and off.
Of course he should not forget to turn it off when storing it.

[rowdy_riemer]

Or maybe must solder a jumper across on the pcb for a permanently closed "switch". Then, the stomp switch does it all. I noticed that it is the first, normally open, switch that closes when inserting the plug that allows the pedal to turn on. I'm guessing the second switch simply grounds the input.

[rowdy_riemer]

Another thing, the first switch is in contact with the negative part of the plug, so it's obviously being grounded. Maybe the stereo jack trick will work with this.

[pablo2011]

Have had another look and you are right, I thought that the jack socket contacts looked a bit different. I've just put in a normal mono jack socket so it will never work due to the switching issue.

So could you elaborate on the stereo switching trick....?

Thanks for your replies!

[rowdy_riemer]

With the stock switch, part of the switch comes in direct contact with the plug, and the other side does not. With a stereo jack, you can wire the connector for the other signal contact to where the other side of the switch should be connected. When you plug in the mono plug, the ground sleeve will complete the connection between ground and the second signal contact. See here: http://www.generalguitargadgets.com/tech-pages/49-building-information/248-general-instructions for basic info. Of course, you will not be wiring the contact to the - terminal of the battery but rather to where the switch contact should connect to the circuit board.

But if you can find a jack similar to the stock one, this would be much better.

[rowdy_riemer]

This, http://www.pedalpartsplus.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PPP&Product_Code=6010&Category_Code=JAC, is a very similar jack, though I can't tell from this if it does any switching. The manufacturer of this jack is the same for the stock jack on the JH-1.

[rowdy_riemer]

If you look closely at the jack here, http://www.smallbearelec.com/Detail.bok?no=770, you can see that this has two normally closed contacts. This is identical to what I see on the output jack on the JH-1. This, of course, is NOT what you want.

[rowdy_riemer]

I don't know if you still have the original jack, but you can see the obvious difference between the normally open switch and the normally closed ones. Can't seem to find any like this online. BTW, don't damage the pots. Two of the pots on mine have bent shafts, and I can't find replacements to save my life, though I can find somewhat similar pots. Another thing, I think the stereo jack trick might not work so well with pcb mounted jacks. Soldering a jumper to the pcb to force the connection to be closed might be the best solution. Of course, you damn well better not forget to turn the pedal off when you unplug the cable, or you'll be buying batteries all the time.

Good luck.

[rowdy_riemer]

Another idea, you can get a jack with the two normally closed switches, and possibly swap the normally opened contact (the one that curls upward) from the old jack with the normally closed on one the replacement jack. Or, if you are good enough at fabricating stuff, you might can modify the nc contact into a normally open one.