Leo27

I bought a 2006 DSL50 off of Ebay. When I turn it on it hums at a low to medium level and when I put my hand on it, I can feel a vibration. The humming is the amp itself, no noise heard from the speakers. The humming does not seem to come from the transformers, no vibration is felt there, it's when I touch the chassis. Otherwise, it performs well. Is this normal? I've not experienced this with any other amp as they are dead quiet when on.

mc_guitar

Hello,

This kind of humming is typical for loose screws on PowerTransformers or if the RecifierDiodes are bad, but then the Amp will collapse in no time, taking the PSU-Caps with it. So it is probably the PT.

Cheers Michael

Leo27

Ah, thank you. I thought that the hum was not right. Time for a service appointment.

EDIT: I took it in for service and initially the tech said he thought it was a delaminating transformer. I'll report when it's fixed.

Leo27

It's a bad transformer. I opted for an upgraded replacement. Mercury, I think...on order.

Leo27

Been a month now. Mercury output transformer's on backorder.

Leo27

This is week 9...says he had to go through 4 transformers to find a good one...and then there's the mounting problem.

Ken

Who is "he", the tech or the Mercury guy...you got 4 bad ones from Mercury??

Ken

Leo27

It's the amp tech. I'm not sure if it's Mercury transformers at this point.

Leo27

The transformer at this point is a UTC. The previous ones to this hummed, had mislabled specs or could not be fitted.

MartyStrat54

Leo: I just caught your thread. I'm sorry that you have been without your amp so long. I have a few questions for you. I Ebay a lot and I was wondering why you didn't contact the seller about the humming? PayPal guarantees your payment and your product. It's sad that a lot of guys are dumping bad Marshalls on Ebay. I have bought two and they both work great.

Whenever I buy an amp that is shipped, I take notice of how it is packed. I always pull the chassis and make sure there isn't any loose parts that could cause a short to occur.

Finally, why did the tech go from a Mercury to a UTC. The Mercury is the better tranny. I can't believe that Mercury is having a problem with stocking DSL50 transformers. It sounds like your amp tech is a meth tweaker. I would have never put up with those excuses. When he gets it in and it works, let me know how it is going. I hope your problems are almost over.

Marty

Leo27

I took me a few days to realize that the loud humming at idle was not right. I did contact the Ebay seller after I took it into the shop but he didn't respond after numerous attempts. I said, "f*ck it" and just gave him bad feedback.

As far as the tech goes, I don't have enough knowledge to be able to support any discussions with him. He seems to know what he's doing, is very busy and in high demand. Besides, it's not like there are techs on every street corner. Very few here. So, it's him, the SamAsh store or some guy that Guitar Center sends you to in Miami.

At this point, he's checking to see if it functions correctly during an extended on time and sounds right.

MartyStrat54

Well it's a shame about your Ebay deal. I would have filed a complaint with PayPal and they would have contacted him. Selling an amp like that without disclosing the tranny problem just shows you what a low life that jerk is.

You would think that in your area there would be more techs, but then again, finding a guy who works on tube equipment is getting harder to find.

Hope you get your amp back soon.

Marty

Leo27

Can't find much info on UTC transformers. Neutral and good in a 6L6 design, maybe a tie to old Fenders.

HAMPAMP TUBE AMP SERVICES

Something sounds FISH LIKE concerning your tech, hope he get's the job done right for you but sounds like he's giving you the "run-around" to me.

MartyStrat54

Don't get me wrong, UTC's are good transformers. It's just that when you are talking Marshall's, Mercury is considered the main upgrade. I've used UTC many times, it's a good product. I'm just looking at this from what you were told that you would be getting, to what you actually got. Yes, it does have an old fish smell to it.

Marty

Leo27

Well, the UTC is not going to work in this amp. We're going with the Mercury that is not a direct drop in replacement and be done with it. Open ended completion date which is OK, got my Engl Screamer to keep me busy.

Leo27

Yep, still waiting...I'm a fool.

MartyStrat54

Holy Horse S**t! You've got to be kidding. I'm sorry, but he's worse than the guy who sold you his amp. He has no excuses left.

Marty

__________________
MARTY

2009 Gibson Explorer-Hell Raising Machine
1989 Fender Strat Plus USA
2008 Fender Tele USA
2004 Schecter Elite w/DiMarzio's

TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers.
TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends."
DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker.

Tubes: Let's just say they are NOS that kick ass.

Leo27

Left a message with his receptionist...waiting for a call back.

Jesstaa

Hey, not meaning to hijack, but I was just wondering;

I bought a JCM900 off ebay from a really nice guy (He was definitely a gear lover, he had a full recording studio and a vintage remake Marshall and stuff, and all of his gear was in top notch condition) and I blew the tubes after not having it for very long (I'd cranked it to 10 on Channel A and turned the gain up a bit hoping for a really vintage sound, but instead I blew out a tube) but before this, it'd been having a little background hum and vibration (Nothing loud, like you could hardly hear it unless you had your ear fairly close) and I was wondering would this be connected to the tube blowing out.

I've been wondering it for a while and I just thought I'd ask now, sorry TS, I suppose I should add my 2 cents.

I'd be talking to the tech face to face now, asking him why he's screwing around, I too have had my amp in for a while just to have them check there's no probs with it, and I'm getting frustrated (about a month they've had it now). And it sucks that you can't get a Mercury transformer for it.

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Leo27

It's a delicate situation if you think about it. One would not want to piss the service provider off lest he do a lousy job fixing the prized possession.
At this point, I have no idea what he's doing.

JESSTAA, I suspect your problem was just the faulty tube.

Jesstaa

Tbh, now that I think of it, I agree with Leo, don't piss them off.

Although if they did a bad job because of personal matters, and it in the end damaged your amp, then you could get them in big trouble.

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Leo27

I was thinking. Maybe mounting the transformer on a heat resistant rubber gasket would help insulate the vibration from being amplified by the chassis into an audible hum.

PaoloJM

The DSL 100 has a cap installed between the plate and screen of the fourth power valve. This helps to reduce the hum that's inherent in the design (I'm afraid to say anything insulting here!!). These are rated quite low at 500V and are prone to failure, causing much hum. I've seen a few go and replace them with a 2kV, 22p cap.

I'm not sure about the DSL 50 has them as I haven't worked on one, but it would be worth checking if that might be the problem.

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Leo27

PaoloJM,

Hum from the head itself not through the speakers??? That's the issue.

Here's the schematic for the DSL50.

http://www.drtube.com/schematics/mar...60-02-iss7.pdf

Leo27

So, the Mercury MAR50-O is on back order....

PaoloJM

Well, hopefully the new OT solves it, if it ever arrives
The schematic for the DSL100 doesn't actually show the cap either.
Seems like it's probably not the problem anyways, hadn't read through the thread fully.
Best of luck.

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Leo27

Supposedly, the transformer has been shipped.

Procter2812

I have a problem on my TSL where there is a hum coming through the speakers at idle and the hum and buzz is the same no matter what volume the amp is at.... you think it could be this cap??/ but surely the hum would increase as the amp went louder??

Leo27

Well, got the amp back today and it doesn't hum anymore with the Mercury. To my surprise, it was the power transformer that was the culprit. Upon examination of the old, stock Dagnall transformer, I see that there's a slight separation of the plates in the middle of one side.