65 Fender Champ input problems

BrokenSkull · Post by **BrokenSkull** » Mon Mar 19, 2012 5:33 pm

I just replaced both input jacks on the champ, along with the 1MegR attached to jack 1. input 1 works fine but input 2 has very week volume, so I removed the 1MR and both inputs worked as they should with the expected noise. Then I reinstalled the 1MR with another new one and the problem returned. Everything looks correct to me, per the layout. any ideas what is happening here?

Thanks

Milkmansound · Post by **Milkmansound** » Mon Mar 19, 2012 6:27 pm

you must have something wired wrong:

[img:226:227]http://www.el34world.com/charts/images/jackwire2.jpg[/img]

if you have the input jacks isolated from the chassis don't forget to ground the second input - its not shown in the above drawing!

BrokenSkull · Post by **BrokenSkull** » Mon Mar 19, 2012 7:45 pm

Take a look it's wired identicle to the pick with the exception of the two wires which run directly to the 68k resistors attached to the board. Either jack works seperately or both will work without the resistor. I've even tried grounding jack 2 with no change. Neither jack is isolated, both ground to the chassis.[/img]

Phil_S · Post by **Phil_S** » Mon Mar 19, 2012 8:50 pm

Are you using brand-name Switchcraft or less expensive knock-offs? The reason I ask is that you can't always go by the pictures with the knock-off. Sometimes the tabs are in a different order and you will need to establish for sure what is tip and what is sleeve.

Firestorm · Post by **Firestorm** » Mon Mar 19, 2012 9:13 pm

BrokenSkull wrote:I just replaced both input jacks on the champ, along with the 1MegR attached to jack 1. input 1 works fine but input 2 has very week volume, so I removed the 1MR and both inputs worked as they should with the expected noise. Then I reinstalled the 1MR with another new one and the problem returned. Everything looks correct to me, per the layout. any ideas what is happening here?

Thanks

When you say "very weak volume," how weak is weak? It's supposed to be half volume (-3dB). If you plug into Input 2, then plug something else into Inout 1, what happens? Both inputs should then go to the full level.

ChrisM · Post by **ChrisM** » Mon Mar 19, 2012 9:13 pm

Looks like maybe the lead of the 1M resistor may touch your cable when its plugged in.

BrokenSkull · Post by **BrokenSkull** » Mon Mar 19, 2012 9:24 pm

Phil_S wrote:Are you using brand-name Switchcraft or less expensive knock-offs? The reason I ask is that you can't always go by the pictures with the knock-off. Sometimes the tabs are in a different order and you will need to establish for sure what is tip and what is sleeve.

These are the real Switchcraft jacks from MojoTone

BrokenSkull · Post by **BrokenSkull** » Mon Mar 19, 2012 9:26 pm

Firestorm wrote:
BrokenSkull wrote:I just replaced both input jacks on the champ, along with the 1MegR attached to jack 1. input 1 works fine but input 2 has very week volume, so I removed the 1MR and both inputs worked as they should with the expected noise. Then I reinstalled the 1MR with another new one and the problem returned. Everything looks correct to me, per the layout. any ideas what is happening here?

Thanks
When you say "very weak volume," how weak is weak? It's supposed to be half volume (-3dB). If you plug into Input 2, then plug something else into Inout 1, what happens? Both inputs should then go to the full level.

Very weak, turn to 10 you can barely hear anything, when I plug in to both jacks both work fin, up to full volume.

BrokenSkull · Post by **BrokenSkull** » Mon Mar 19, 2012 9:29 pm

ChrisM wrote:Looks like maybe the lead of the 1M resistor may touch your cable when its plugged in.

Just checked and there's plenty of room, looks close in the pic but I have about 3/16"

LeftyStrat · Post by **LeftyStrat** » Mon Mar 19, 2012 9:38 pm

With a plug inserted into jack 2, measure the resistance between the tip and ground.

BrokenSkull · Post by **BrokenSkull** » Mon Mar 19, 2012 9:46 pm

LeftyStrat wrote:With a plug inserted into jack 2, measure the resistance between the tip and ground.

Jack 2 is 134.9 ohms. jack 1 reads 1meg

Firestorm · Post by **Firestorm** » Mon Mar 19, 2012 11:02 pm

Did you change the resistors on the board?

Tillydog · Post by **Tillydog** » Mon Mar 19, 2012 11:05 pm

My 0.02p:

Check that the solder on the tip contact hasn't shorted the tip & switch contacts on the RH jack.

What is soldered to the sleeve contact on the LH jack?

Andy

Milkmansound · Post by **Milkmansound** » Tue Mar 20, 2012 1:31 am

in the above highlighted picture - I see that the lead of the 1M resistor is not poking through the 2 holes of the input jacks. Make sure you do that to hold the whole assembly together

then hook the 68k through there and solder it all together at once

I usually put it through the front holes of the amp backwards to get the spacing right then swing it around to the other side and thread the nuts on

BrokenSkull · Post by **BrokenSkull** » Tue Mar 20, 2012 2:09 pm

Firestorm wrote:Did you change the resistors on the board?

Yes both 68K R's have been replaced with new.

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