5E5-A channel bleed

[punkykatt]

Hey Guys, I built a 5E5-A using the Fender layout. The amp seems to operate normal and all voltages are within spec.  When I plug the guitar into channel 1  with channel 1 volume off, when I turn channel 2 volume up past 1/3 rotation I can hear the guitar signal coming through and gets quite loud when turned all the way up. (about 1/4 of the full volume of the amp) Same thing happens if I plug the guitar into channel 2 with channel 2 volume off and turn channel 1 volume up.  Lead dress from input jacks to the resistors on board is about 3" and the same or even less from the board to V1 tube socket. Is this signal bleed through normal for this amp? Input jacks are not shorted as far as I can tell. The Hi and Lo are working correctly, the 1M resistors on the jacks test good. Is there any other tests I can do?  Thanks in advance for any help.  Punky

[TubeGeek]

From what you describe this is normal for these tweed circuits.  Ever play a 5e3?

The volume controls are interactive.  

[punkykatt]

http://www.el34world.com/charts/Schematics/files/fender/pro_5e5a_schem.pdf

The 5E5 is wired like the 5E3 where the volumes interact. The 5E5-A is wired different.

[HotBluePlates]

I'd be looking more at the volume pots. But the ground for the pots is probably good, if you can get a channel to turn all the way off when its volume is at zero.

There shouldn't be bleed through the mixing resistors if a given channel is at 0 with a good ground on the volume pot. But if it's not causing obvious problems, it may not be a problem.

I suppose it's possible for bleed-through from one side of the input triode to the other.

Or maybe you shouldn't play through your amp with the volume on zero. 

[punkykatt]

Or maybe you shouldn't play through your amp with the volume on zero.  You are right,  Thats how I found the amp was donig that. I was plugged into Ch 1 and turned Ch 2 volume  by mistake and wondered why the amp sounded like only a 10w amp?? If it were my amp to keep I would use a jumper cord connecting both inputs as I do on my 5E3  and plexi builds I gig with  The grounds on the volume pots are good, with both pots at "0" I get no sound no how no way. The Guy spent a lot of money on pots, caps and trannies for this amp and I just want to make sure the amp is what its suppose to be.
I built a 5E5-A a few years ago and don`t remember the bleed through between channels, I don`t remember testing for it either.  If any of you guys happen to have this style amp, please give it a try and see if you get any bleed through between channels and let me know.  Thanks in advance for your time and trouble.  punky

[HotBluePlates]

I have a 5F4 Super copy, and don't remember it to have any bleed through. But then again, I can't say I ever checked to see if it occurred.

Unfortunately, that amp is several states away, so I can't check for you.

[punkykatt]

Thanks HBP, I just talked to the guy I built one for a few years ago, He said he may be back in town with the amp sometime in April. Im not going to hold my breath on that!! Here are some of the other Fender amp models that have the same input set up:  5F4 Super, 5E4-A Super, 5E7 Bandmaster, 5D8 Twin, 5E8-A Twin, 5F8 Twin, 5F8-A Twin,  Hopefully one of you might have one of these amps to test channel bleed through for me???  Punky

[sluckey]

The schematic you linked to does not have a ground on either volume pot. Layout is correct. How 'bout your amp?

[punkykatt]

Yes sluckey, Both volume pots in the amp are grounded to a 14 AWG  copper wire buss above the pots and connected to the input jacks ground via ring terminal and bolted to chassis near inputs. That is an error on that schematic. I copied it from the schematic listing here.  Is it possible to draw in a ground symbol to correct that schematic?

[sluckey]

I didn't think that was an issue. Fender has several schematic booboos. Some of those other amps you mentioned have the same schematic error. Those schematics are all over the web. Impossible to correct all of them. Besides, you know how it's supposed to be.

I wonder if splitting the cathodes of the preamp tubes would fix the crosstalk?

[punkykatt]

I wonder if splitting the cathodes of the preamp tubes would fix the crosstalk?  I tried that this morning using separate R/C`s for each cathode on V1 and it cut down the crosstalk considerably. Now you have to turn the opposite volume  almost wide open to get any crosstalk.  Thanks  sluckey