# Ygm4 reverb static noise



## pauledc (Mar 4, 2013)

Hi all, new problem. My amp is making a bad static noise that gets worse when I turn up the reverb. I swapped tubes with no help. The noise is there with the verb pot off and gets better when the volume pot is turned up.

I took the pan off. Looked like it was good. Cleaned the contacts. Still static. I disconnected the pan and still static?

Any trouble shooting help would be great.

Thanks again


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## pauledc (Mar 4, 2013)

So it turns out my son moved back yesterday and his monster gaming computer is on the circuit causing the noise. Should of thought of that first.

Now my reverb sounds weak with a short almost slap back decay? Not sure what I did or where to look? Before it was over the top nice reverb.:confusion:


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## nonreverb (Sep 19, 2006)

Try reversing the leads to the tank.


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## pauledc (Mar 4, 2013)

nonreverb said:


> Try reversing the leads to the tank.


Thanks nonrevrb. Perfect username for my situation.

The leads are good. One is longer so the other cant reach the jack.

It sounds like a crappy digital sort delay. I've touched up all the solder joints to rule that out. 

What sort of ohm reading should I be getting? I'll take readings later when time permits.

Cheers


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## jb welder (Sep 14, 2010)

Tank resistance readings should be around 200 ohm at input end, 215 ohm at output.
If those check out, take another look inside the tank. Make sure the main springs are intact, and the 4 springs that secure the inner pan to the outer casing.

P.S. "The leads are good. One is longer so the other cant reach the jack". If the tank gets put back in place reversed, then you can end up with reversed leads.


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## pauledc (Mar 4, 2013)

jb welder said:


> Tank resistance readings should be around 200 ohm at input end, 215 ohm at output.
> If those check out, take another look inside the tank. Make sure the main springs are intact, and the 4 springs that secure the inner pan to the outer casing.
> 
> P.S. "The leads are good. One is longer so the other cant reach the jack". If the tank gets put back in place reversed, then you can end up with reversed leads.


Thanks jb welder, input is 176 ohm output is 169 ohm.

Looks like I need a new tank. Hopefully long and mcquade still has them

Cheers


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## pauledc (Mar 4, 2013)

The transducers are quite wiggly as well. Not sure if that's normal?


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## jb welder (Sep 14, 2010)

Those numbers are not far off, I think they are close enough. The transducers usually have some wiggle. 
Static noise is not really a fault I've ever seen caused by a defective tank (aside from broken springs), I think the problem would more likely be a noisy resistor or some other component in the reverb circuitry.
Yorkville (via L&M) has the tank for the YGM3 re-issue listed as part # 9945 at a $79, which seems fairly pricey as far as reverb tanks go.

Edit: just re-read your original post, if turning the reverb pot off doesn't kill the noise, then it's not coming from the reverb.
Have you tried cleaning the pots?


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## pauledc (Mar 4, 2013)

jb welder said:


> Those numbers are not far off, I think they are close enough. The transducers usually have some wiggle.
> Static noise is not really a fault I've ever seen caused by a defective tank (aside from broken springs), I think the problem would more likely be a noisy resistor or some other component in the reverb circuitry.
> Yorkville (via L&M) has the tank for the YGM3 re-issue listed as part # 9945 at a $79, which seems fairly pricey as far as reverb tanks go.
> 
> ...


Actually i found the static was from my sons computer being on the same circuit i was plugged into...its now plugged into a different circuit in the house and is quiet and everything sounds great but the reverb.

(not knowing it was the computer causing all the noise) after messing with the amp, cleaning pots, jacks, plugs to reverb tank, removing and inspecting the tank. it now sounds really bad / weak / more like an bad digital echo pedal.

i'll check the resistors in the circuit and see if they are out of whack.

i read on another thread you recommend a mod tank... i looked it up and its way too long. mines the 9" guy attached to the amp chassis. any recommendations for a mod tank that would work and may sound better?


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## jb welder (Sep 14, 2010)

Was the reverb sounding ok before you opened the amp? If so, it's probably not the tank that is bad. Triple check everything.
If the reverb sounded poor before, then yes it could be a tank issue.
I'm pretty sure the Mod 8FB3C1B should be correct, but if your tank has any numbers on it, please post.
With the above Mod tank, you would need to change the ground jumpers at each end. It's real simple, just a solder blob across a couple copper pads on the little circuit boards in the tank. When you see inside the Mod tank it will make sense, you remove the bridge on one end of the tank and add it in at the other end.


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## pauledc (Mar 4, 2013)

Yes it was ok before. Actually at2 it was perfect. A little much.

The pan stamp is hard to read...smudge. My guess is it is 4fb2b1b which is what's listed on the schematic.


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## jb welder (Sep 14, 2010)

If the tank was ok before, I don't see any reason it should have gone bad. The resistance readings seem ok and you said the springs looked good in the tank. It could be something as simple as a dirty tube socket so wiggle those preamp tubes around and see if it helps or makes the reverb cut in and out.
But I guess the Mod tanks are cheap enough to try, just keep the old one in case the tank is not the problem.
Tanks that start with 4 (like listed in the schematic) are 16.75" long, you said yours was the short type (9.25") so it needs a tank that starts with 1 or 8. type 1 are not very common, but 8 are. The type 8 have 3 spring where the type 1 have 2 spring.
The part number on yours that is smudged may be Yorkville's own part number. But there is only one type shown on the various schematics so I would think it's the same basic impedance tank, just the different length. That's why I figured 8FB3C1B should work as the short version of the 4FB3B1B.


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## Church-Audio (Sep 27, 2014)

Check continuity on your reverb wires going to the tank. Also if you have cracking in the amp with the reverb off you might have a tube issue. I woukd take one known good preamp tube and try it one preamp tube at a time to see if the crackle goes away if not then you might need new power tubes. But it's really hard to diagnose this over the Internet. Start with tubes check the tank wires. Make sure your getting readings at the end of the cable with the tank hooked up but disconnected from the inside of the amp just have to pull the centre wire on the rca connectors.


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## nonreverb (Sep 19, 2006)

If it's an opamp driven reverb, which many amps now are, you might have a problem there.


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## pauledc (Mar 4, 2013)

Thanks again Jb Welder. Actually now that you mention it the smudge does look more like a 1 than a 4. my best gues would be 1F53818 the other numbers are 3572 50 76 337. it is 9.25" with 2 springs. so i have the uncommon one. would the impedance match for the mod 8FB3C1B? the only thing i haven't checked is the pot. Maybe cleaning it with the spray made it weak?


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## jb welder (Sep 14, 2010)

3572 is the yorkville part number. According to their parts catalog it was a 1EB2C1C.
But from your description of the smudge, sounds more like 1FB3B1B.
The 8FB3C1B should match impedance wise, and have a bit longer delay.
The schematic calls for an FB impedance tank. So even though they may have used an EB later on, I think the FB type is the best match.
Yes, sprays can make the pots act funny, especially while still wet. I would give the pot lots of exercise, maybe another shot of spray, and also work the preamp tubes in and out of their sockets a few times in case of dirty contact at a tube socket. Also exercise the connectors to the reverb tank.


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## pauledc (Mar 4, 2013)

Ok thanks everyone for there help. i'll go over everything once more...get a reading on the pot and if all fails will order the mod. the long decay may be nice. Then this ygm will make me forget letting go of my old deluxe reverb.

cheers


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## pauledc (Mar 4, 2013)

New mod tank arrived and all is working well! The long reverb is nice.

Cheers


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