Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TerryD on October 28, 2017, 09:24:38 am
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I want to put a "real" input jack on my friends Hot Rod Deluxe. I don't know if I'm using the right terminology but how can I tell where to put the wire for the ground switch. I can tell the ground from the positive by putting a jack in and using a multi-meter. But the ground switch that turns it off when there is no plug in the jack, how do you tell that point?
Thanks, Terry
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1) look at the datasheet.
2) insert a 1/4" jack. with an ohmmeter find the tip lead & sleeve lead(s). by default the remaining is the switch lead.
--pete
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where to put the wire for the ground switch.
the wire typically grounds the tip when nothings plugged in, so it goes from tip to ground
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Thank you.
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This is a common modification on both Hot Rod and Blues versions of Fender amps. Torres Engineering even sells a kit for it:
http://torresengineering.stores.yahoo.net/newjacrepkit.html (http://torresengineering.stores.yahoo.net/newjacrepkit.html)
I've done this on several of these amps as well. Check out the two attached files
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On a Fender amp where I have seen this done, the PCB-mount jack had a separate pin for the connection that's shorted with nothing plugged in. This had its own hookup point on the PCB,
which could be identified by ultimately being on the same PCB trace as the ground...
But you can also hook this to the ground of the jack itself and use only wire to the ground on the board. EDIT: slucky pointed out this might not be a good assumption, and this shortcut wouldn't work with hi/low level jacks.
You can usually examine the original PCB mount jack to determine the layout of the different connections on the PCB and use them accordingly with the new jack.
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On a Fender amp where I have seen this done, the PCB-mount jack had a separate pin for the connection that's shorted with nothing plugged in. This had its own hookup point on the PCB, which could be identified by ultimately being on the same PCB trace as the ground...
But you can also hook this to the ground of the jack itself and use only wire to the ground on the board.
That won't work for every input jack on amps that have "Hi" and "Lo" input jacks such as Hotrod Deluxe, or the reissue blackface amps. The Hi jack does connect the switch terminal to ground but the Lo jack connects the switch terminal to the Hi jack tip terminal.
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On a Fender amp where I have seen this done, the PCB-mount jack had a separate pin for the connection that's shorted with nothing plugged in. This had its own hookup point on the PCB, which could be identified by ultimately being on the same PCB trace as the ground...
But you can also hook this to the ground of the jack itself and use only wire to the ground on the board.
That won't work for every input jack on amps that have "Hi" and "Lo" input jacks such as Hotrod Deluxe, or the reissue blackface amps. The Hi jack does connect the switch terminal to ground but the Lo jack connects the switch terminal to the Hi jack tip terminal.
Good catch. And of course, Fender amps are often configured like this.
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So, I'm a little confused now. Can I change just one input to a swtchcraft jack on the Hot Rod Deluxe?
A guy on YouTube does one and removes the grounding wire because with the switchcraft its now grounded at the chassis.
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I'm a little confused now
this may help, start at page 7. This is a great pdf :laugh: also showed me 1 jack is ALWAYS best :icon_biggrin:
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I would change them both
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Here's a complete tutorial: http://hotroddiy.com/howtoarticles.php (http://hotroddiy.com/howtoarticles.php)
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I've done this on mine (blues deluxe) because the plastic ones came out. It worked great for me. I did a youtube video on it a while ago, can't be sure where it is, I'd have to hunt if interested.
~Phil
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Phil, I'm very very interested. This is the first time, on this board, that I'm a little more than confused.
Thanks for the effort.
Terry
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I know the 1-2 input jack is foreign when one is not used to it but once you've done a few you'll be amazed how simple it is
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Phil, I'm very very interested. This is the first time, on this board, that I'm a little more than confused.
Thanks for the effort.
Terry
Found it, not sure if my video will be helpful though, let me know if it is or isn't :P
~Phil