Noisy Input Jacks On 5E3

tele-martini · June 13th, 2008, 08:37 AM

My 5E3 clone I built last February has given me problems off and on since I built it. Last night I unpugged my guitar cord and the amp went into loud static fits and I couldn't hit the standby switch fast enough.The problem is with the input jacks. I've re-wired them 3 times and changed ground bus twice. These jacks were from a Marsh kit . I want to order new ones. should I just get Switchcraft Tip Shunt shorting type ?
Thanks,
Gene

sjhusting · June 13th, 2008, 08:55 AM

yes

Switchcraft 12A.

Wire them as described here -

http://www.el34world.com/charts/CommonHookups.htm

steven

LeroyBlues · June 13th, 2008, 09:12 AM

You might want to check your tube sockets for any shorts. I built one last year and it did a similar thing. Was intermittent. If you plugged or unplugged the guitar cord, or even gave the cabinet a firm tap with your hand, sometimes it would make a staticy squealing microphonic noise. Loud too. On very close inspection of the 12AY7 tube socket, I could see that two of the solder tabs (I think it was the #6 and #7 tabs) were very close. I guess when I was trying to tuck the wires neatly away, one of the tabs must have been pulled towards the other and I didn't catch it. But after that minor problem and simple fix, it's a dream amp. Some of the more amp tech kinda guys might have another thought about it, but it's something to check out.

tele-martini · June 13th, 2008, 09:25 AM

Quote:

Originally Posted by LeroyBlues

You might want to check your tube sockets for any shorts. I built one last year and it did a similar thing. Was intermittent. If you plugged or unplugged the guitar cord, or even gave the cabinet a firm tap with your hand, sometimes it would make a staticy squealing microphonic noise. Loud too. On very close inspection of the 12AY7 tube socket, I could see that two of the solder tabs (I think it was the #6 and #7 tabs) were very close. I guess when I was trying to tuck the wires neatly away, one of the tabs must have been pulled towards the other and I didn't catch it. But after that minor problem and simple fix, it's a dream amp. Some of the more amp tech kinda guys might have another thought about it, but it's something to check out.

For me it always comes back to either a bad solder connection or a ground problem. I have checked these connections a bunch of times under bright light and magnification. The reason i think the problem involves the input jacks is because it's the only area that responds to chopsticking. Just tapping the tips of the jacks with the chopstick causes buzzing and noise. The wiring and soldering appears to be sound though.

sjhusting · June 13th, 2008, 09:33 AM

Quote:

Originally Posted by tele-martini

The wiring and soldering appears to be sound though.

Don't mean a thing. Bad joints can still look good. Try reflowing the solder on the jacks before you replace them

steven

Guitarslinger1 · June 13th, 2008, 10:01 AM

Quote:

Originally Posted by tele-martini

For me it always comes back to either a bad solder connection or a ground problem. I have checked these connections a bunch of times under bright light and magnification. The reason i think the problem involves the input jacks is because it's the only area that responds to chopsticking. Just tapping the tips of the jacks with the chopstick causes buzzing and noise. The wiring and soldering appears to be sound though.

Sounds like one or more of your jacks is not shorting when unplugged. Spray them with contact cleaner. Visually inspect them. Using your chopstick, with the amp on and the volumes up, very gently push the tip contact of each jack into its shorting contact. See if this makes it quiet.

tele-martini · June 13th, 2008, 12:55 PM

Quote:

Originally Posted by Guitarslinger1

Sounds like one or more of your jacks is not shorting when unplugged. Spray them with contact cleaner. Visually inspect them. Using your chopstick, with the amp on and the volumes up, very gently push the tip contact of each jack into its shorting contact. See if this makes it quiet.

Yes this is my exact thinking. I'm not sure if the jacks that came with the Marsh kit were of inferior quality or if I just had one or more bad ones. I thought by installing new jacks I would eliminate that possibility. i'm thinking by jarring the amp a little I'm re-connecting the switch to tip. It only takes 5 minutes to reflow solder and spray a little contact cleaner though. I'll do that first.

JohnnyCrash · June 13th, 2008, 02:18 PM

How are the inputs grounded?

While it could be a few things, it "feels" like a grounding issue to me. Poor grounding (weak connection), bad ground location, etc.

How is your amp's ground scheme in general?

Also, remember to keep high current grounds away from low current grounds.

tele-martini · June 14th, 2008, 10:25 AM

Quote:

Originally Posted by JohnnyCrash

How are the inputs grounded?

While it could be a few things, it "feels" like a grounding issue to me. Poor grounding (weak connection), bad ground location, etc.

How is your amp's ground scheme in general?

Also, remember to keep high current grounds away from low current grounds.

Well I had a lot of problems when I first built this amp with grounding. After isolating the High voltage and low voltage grounds the amp performed beautiful. After a couple months working well ,the problem started with the amp going into a static noise which would stop and return to normal when the amp was slapped on the side or jarred somehow. After checking and rechecking solder joints ,reflowing questionable ones and chopsticking every joint it always seems to center around the input jacks.

I basiclly have the AC ground isolated to far left of chassis. The PT ground and HV caps grounded on left side of chassis seperately. I have the low voltage grounds from board , the input jacks and the sheilded cables grounded on far right of chassis.This was a major breakthru when I first built the amp and corrected the initial problems.

Recently I have been experimenting with different NOS tubes in this amp.This seems to have had no effect with the on again/off again noise and static problem.

I will continue to de-bug this problem and will post with any new info.

Thanks for the help !!
Gene

JohnnyCrash · June 14th, 2008, 12:39 PM

Sounds like a loose or poor ground if hitting the amp makes it better.

Make sure your grounds get maximum metal to metal contact. Keeping grounds to a minimum helps too. Filter caps get one, the preamp side gets one - it's easier to troubleshoot two grounds instead of 5.

zook · June 14th, 2008, 01:26 PM

I've had this problem every now and then with a poor ly grounding jack. Even Switchcrafts, which I use can have that happen to them. Change out the ones for the Switchcrafts anyway. If thay's not the problem you have at least put high quality jacks in, and they're no really expensive.

Winnie

tele-martini · June 15th, 2008, 09:29 AM

Problem solved.

Turns out the input jacks were fine. Somehow traced problem back to a board terminal where the 25uf cap and 1.5K resistor go to ground. reflowed solder connection and played amp for a solid hour with no noise or on again/off again scratchy static. This would explain why notes played in the very low bass register were producing noise when played at louder volumes. I realize now that I was loosing ground to the 1.5k resistor when the cab was vibrating from loud volume or other external sources.Still not sure why input jacks were affected?
Phew.....what a releif to have my 5E3 clone functioning soundly again !
Thanks again,
Gene

June 13th, 2008, 08:37 AM	#1 (permalink)
tele-martini Tele-Holic Join Date: Sep 2006 Location: Hilton, NY Age: 49 Posts: 901 11 Photos	Noisy Input Jacks On 5E3 My 5E3 clone I built last February has given me problems off and on since I built it. Last night I unpugged my guitar cord and the amp went into loud static fits and I couldn't hit the standby switch fast enough.The problem is with the input jacks. I've re-wired them 3 times and changed ground bus twice. These jacks were from a Marsh kit . I want to order new ones. should I just get Switchcraft Tip Shunt shorting type ? Thanks, Gene __________________ Nothing is more beautiful than a guitar, except, possibly, two. ...Frederic Chopin

June 13th, 2008, 08:55 AM	#2 (permalink)
sjhusting Tele-Holic Join Date: Jul 2003 Location: Germany Posts: 621 14 Photos	yes Switchcraft 12A. Wire them as described here - http://www.el34world.com/charts/CommonHookups.htm steven __________________ Go octal

June 14th, 2008, 01:26 PM	#11 (permalink)
zook Tele-Holic Join Date: Aug 2003 Location: Northeast Kingdom, Vermont Posts: 801	I've had this problem every now and then with a poor ly grounding jack. Even Switchcrafts, which I use can have that happen to them. Change out the ones for the Switchcrafts anyway. If thay's not the problem you have at least put high quality jacks in, and they're no really expensive. Winnie __________________ I have noticed that happy people are often evaluating themselves and unhappy people are always evaluating others. -William Glasser

June 15th, 2008, 09:29 AM	#12 (permalink)
tele-martini Tele-Holic Join Date: Sep 2006 Location: Hilton, NY Age: 49 Posts: 901 11 Photos	Problem solved. Turns out the input jacks were fine. Somehow traced problem back to a board terminal where the 25uf cap and 1.5K resistor go to ground. reflowed solder connection and played amp for a solid hour with no noise or on again/off again scratchy static. This would explain why notes played in the very low bass register were producing noise when played at louder volumes. I realize now that I was loosing ground to the 1.5k resistor when the cab was vibrating from loud volume or other external sources.Still not sure why input jacks were affected? Phew.....what a releif to have my 5E3 clone functioning soundly again ! Thanks again, Gene __________________ Nothing is more beautiful than a guitar, except, possibly, two. ...Frederic Chopin

June 13th, 2008, 09:12 AM	#3 (permalink)
LeroyBlues TDPRI Member Join Date: Apr 2008 Location: Michigan Posts: 65 5 Photos	You might want to check your tube sockets for any shorts. I built one last year and it did a similar thing. Was intermittent. If you plugged or unplugged the guitar cord, or even gave the cabinet a firm tap with your hand, sometimes it would make a staticy squealing microphonic noise. Loud too. On very close inspection of the 12AY7 tube socket, I could see that two of the solder tabs (I think it was the #6 and #7 tabs) were very close. I guess when I was trying to tuck the wires neatly away, one of the tabs must have been pulled towards the other and I didn't catch it. But after that minor problem and simple fix, it's a dream amp. Some of the more amp tech kinda guys might have another thought about it, but it's something to check out.

June 13th, 2008, 02:18 PM	#8 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Lost Angeles and Orange County Posts: 7,128	How are the inputs grounded? While it could be a few things, it "feels" like a grounding issue to me. Poor grounding (weak connection), bad ground location, etc. How is your amp's ground scheme in general? Also, remember to keep high current grounds away from low current grounds.

June 14th, 2008, 12:39 PM	#10 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Lost Angeles and Orange County Posts: 7,128	Sounds like a loose or poor ground if hitting the amp makes it better. Make sure your grounds get maximum metal to metal contact. Keeping grounds to a minimum helps too. Filter caps get one, the preamp side gets one - it's easier to troubleshoot two grounds instead of 5.