Quick question about Vibro Champ speaker out

[vortex]

I was just about to replace the RCA speaker out jack with a 1/4" jack on my Vibro Champ. With the speaker not attached I am getting continuity from chassis ground to both the hot and ground lugs on the jack.

That's not right is it? Please confirm!

Thanks!

PS Amp appears to be working fine in current condition.

[vortex]

Well, just installed the 1/4" jack and all is well. Perhaps the continuity is through the transformer?

[stokes]

You will read continuity between the "hot" lug because the secondary only has 1ohm or less dc resistance.That jack should be a shorting jack which shorts the hot to ground when nothing is plugged in.

[Bruce / Mission Amps]

If it is an RCA jack there is no shorting bar but yes the OT has very low DC resistance on it's secondary and it will look like a dead short.
Typically, .4 to .7 ohms is not unusual.
Check your ohm meter first with the leads touching to give you a starting point.
You'll be measuring the DC resistance of your meter leads and anything else inside the device. Now subtract that small number from the reading you get across the jack and you'll see the actual secondary DC resistance.
If you did replace it with a shorting jack, you'll have to open the contact points of the shorting bar with a business card or a blank 1/4" phone plug with no wires on it.

[vortex]

You will read continuity between the "hot" lug because the secondary only has 1ohm or less dc resistance.That jack should be a shorting jack which shorts the hot to ground when nothing is plugged in.

Hmmm... the original RCA jack isn't a shorting jack. I installed a regular 1/4" stereo jack and used the tip (hot) and sleeve lugs (grd). Is there any danger to the amp with what I've done? Thanks for the help!

[stokes]

There is no harm as long as you dont run the amp with the speaker disconnected.The shorting jack is a kind of safety in case you do forget to plug the spkr.back in.Most stock Fenders I have seen have the shorting jack for the main spkr and the non shorting type for the ext.spkr.Of course the Vibro doesnt have an ext.jack.

[Tom Phillips]

... I installed a regular 1/4" stereo jack and used the tip (hot) and sleeve lugs (grd).

You don't mention the other lug. Note that unless you hook the shorting bar lug to ground it won't be doing anything and the jack will function just like a non-shorting version.

[vortex]

Thanks to all for the info, much appreciated!

There is no harm as long as you dont run the amp with the speaker disconnected.The shorting jack is a kind of safety in case you do forget to plug the spkr.back in.

In the 25+ years I've played tube amps, I've never forgotten to plug the speaker in before power up so I'm not too worried about it.

Quote:Originally Posted by vortex
... I installed a regular 1/4" stereo jack and used the tip (hot) and sleeve lugs (grd).

You don't mention the other lug.

The ring lug is not connected.