Eden WT-550 Constant Hum

[dpaulb]

I purchased a WT-550 which has a constant hum. Nothing connected but my Bag End S15X-D. It isn't effected by the positions of the controls. I inserted a cable into the effects loop jacks with no change. I removed the lid and found one wire from the D.I. circuit board not connected. I am wondering if it is to the ground/lift switch. Because it only has 1 wire connected. Could this be the reason for the hum? I think it sounds absolutely wonderful except the constant hum.

 

[dpaulb]

Today the hum is barely audible. Without a bass plugged in and master at maximum, bass at maximum while turning the gain past 1:00 there was a loud oscillation coming from the speaker that shook the room. Of course I immediately turned it down. Just now I set the master at 12:00, tone controls flat and the gain was at 1:00 i turned the bass up just a bit from 12:00 and the low frequency oscillation started again. Is that because of the preamp tube? Noise not hum increases as I turn up the gain. Whilst playing a bass with the gain up where the red light comes on occasionally, the bass at maximum and the master at 1 or 2 the oscillation doesn't happen.

 

[Bassist30]

You need to have the capacitors changed. That should fix the problem.

 

[seamonkey]

Looks like that green wire fell off the center lug of the ground lift switch.
Check to see if it has continuity with Pin 1 on the XLR
I don't see how this would be the cause of a hum but leaving hanging wires around isn't a good idea. Maybe somebody changed the ground lift switch and didn't do a good job soldering it back on.

And what under that wad of electrical tape by the DI output pot?

As always, it would be a good time to have an experienced tech do a once over for other possible service problems. Find a tech that will actually check things out and isn't going to shotgun replacement of all the caps!

 

[agedhorse]

You need to have the capacitors changed. That should fix the problem.

Probably not, and certainly not if the cause is unrelated to the capacitors.

Just changing random parts is how amps end up getting damaged from mistakes made.

 

[dpaulb]

Could the hand writing on this capacitor mean anything?

 

[Bassist30]

Have the exact amp. Had the exact problem. Had the Capacitors changed. Quiet and sounds great.. Remember these are semi old amps. So I'm sure you didn't buy it new All I know about these amps is that they sound great. If you bought it used and have no idea how many owners or hours its been played it needs a professional to examine it. Not near you but you may want to check Winston Electronic in your state.

 

[agedhorse]

Could the hand writing on this capacitor mean anything?
View attachment 5119422

Looks like QC notes, things that needed to be fixed before shipping. Odd that it was left on the amp.

 

[agedhorse]

Have the exact amp. Had the exact problem. Had the Capacitors changed. Quiet and sounds great.. Remember these are semi old amps. So I'm sure you didn't buy it new All I know about these amps is that they sound great. If you bought it used and have no idea how many owners or hours its been played it needs a professional to examine it. Not near you but you may want to check Winston Electronic in your state.

There are many possible causes for hum. Just because YOUR amp was fixed by replacing a cap doesn’t begin to mean that it’s the solution for other amps.

Thus is a common misconception when it comes to attempting to repair anything.

 

[dpaulb]

Have the exact amp. Had the exact problem. Had the Capacitors changed. Quiet and sounds great.. Remember these are semi old amps. So I'm sure you didn't buy it new All I know about these amps is that they sound great. If you bought it used and have no idea how many owners or hours its been played it needs a professional to examine it. Not near you but you may want to check Winston Electronic in your state.

Thanks. I will check on them. I have been looking for a good one.

 

[Bassist30]

There are many possible causes for hum. Just because YOUR amp was fixed by replacing a cap doesn’t begin to mean that it’s the solution for other amps.

Thus is a common misconception when it comes to attempting to repair anything.

Very true regardless of the problem it should be solved if someone experienced can examine the amp. Im just saying the problem i had with the WT 550 was the same and what it was that fixed mine. I hope when he does have it fixed he can come back here and tell us what it was.

 

[beans-on-toast]

I don’t like the look of the disconnected green wire. Could be a ground wire and the cause of the hum.

 

[agedhorse]

Since the green wire comes from pin 1 of the DI out, it’s not related to the hum. It’s isolated to the DI jack.

 

[dpaulb]

Thank you.
The hum has been barely audible since Sunday morning. Very happy with the sound of it. I am still going to have a tech check it over though.

 

[agedhorse]

If the hum is barely audible under the conditions you posted earlier (master all the way up) then it’s not bad caps, they don’t miraculously cure themselves.

There could be an intermittent switch contact, or it could be something as simple as an intermittent ground terminal on the power receptacle.

I suggest leaving it alone unless the problem returns and you can get more information.

 

[dpaulb]

If the hum is barely audible under the conditions you posted earlier (master all the way up) then it’s not bad caps, they don’t miraculously cure themselves.

There could be an intermittent switch contact, or it could be something as simple as an intermittent ground terminal on the power receptacle.

I suggest leaving it alone unless the problem returns and you can get more information.

I will heed your advice.
Thanks again.