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EBS HD350 fault

R

rhughes44

Mar 15, 2004
1
0
#1
Just bought a mint condition EBS HD350 head s/h.
Got 2 problems...
1. With Master set to 0 (and all tone/gain controls flat) I get a quiet very distorted bass sound through the cab.
As I increase the Master, the normal sound takes over, so at playing volume it sounds OK
I have tried different basses/cabs/settings, but can't get rid of it..
2. When I power off - I get a screech and pop through the speaker

Anyone else had this problem with an HD350 or another head...?
Are these just annoying or symptoms of an imminent disaster onstage?
Advice very much appreciated.
 
#2
I've got a Mesa amp that does the exact same volume thing, and had a SWR
that popped and screeched when switched off. These symptoms were
normal for my amps... yours could be too.


You might dig up some info here...
Link Removed

If not, try sending them an e-mail with your concerns and then post your findings here...:)
 
#4
i also have got these problems with my td650. it does it for 2 years now, it is not getting better or worse. i have no trouble with that at rehearsals or onstage but it is not possible to play on low leves at home. only way to fix is to turn up the master-volumen and to reduce gain dramatically.

if it would not sound so brilliant i would have sold it because of these problems ...

sandmann
 
#6
I'm looking at maybe grabbin one of the 350's.
But I'm curious if there are some owners out there that DO NOT have this problem.
Just want to make sure this isn't a wide spread thing, since I might possibly buy on online, without hearing it first.
 
#7
The 350 is a really great sounding amp better that my Eden WT 550.But I sent an e-mail to EBS about this distortion problem and have not gotten a response.It's been a week.I'll try again tomorrow.Anyway, I don't want to send my amp away to get fixed I guess I can live with that problem as long as it doesn't get worse.It would be nice though if there was a simple fix for that.
 
#8
Problem solved.The amp started to make weird crackling rumbling noises just by tapping on it with no instrument plugged in.So I opened it up to check all the connections between the compnents and also turned it upside down and shook it and blew it out to remove any loose particles and that did it.The crackling and rumbling stopped and as an added bonus the distortion at low volues is also gone now.So something must have gotten in there and created some kind of short I guess.
What a nice surprize that the solution was so simple.I still wish I would have gotten a response from EBS.
 
#9
gimmeagig said:
Problem solved.The amp started to make weird crackling rumbling noises just by tapping on it with no instrument plugged in.So I opened it up to check all the connections between the compnents and also turned it upside down and shook it and blew it out to remove any loose particles and that did it.The crackling and rumbling stopped and as an added bonus the distortion at low volues is also gone now.So something must have gotten in there and created some kind of short I guess.
What a nice surprize that the solution was so simple.I still wish I would have gotten a response from EBS.
Click to expand...

Wow. Hope everyone else's fix is as easy as that.
 
#10
Update:
The distortion came back and I tried to contact EBS again.Turned out that their response had ended in my spam folder, that's why i never saw it.
Anyway here's the solution I got from them:
Take off all the knobs,open the box and while you are holding the pots tighten the nut that holds them on the front of the face plate.They need to make good contact to the plate.
If that does not fix it, take out the cirquitboard and sand off the inside of the face plate.
All I had to do was tighten the nuts problem solved.For real this time!
 
#11
gimmeagig said:
Update:
The distortion came back and I tried to contact EBS again.Turned out that their response had ended in my spam folder, that's why i never saw it.
Anyway here's the solution I got from them:
Take off all the knobs,open the box and while you are holding the pots tighten the nut that holds them on the front of the face plate.They need to make good contact to the plate.
If that does not fix it, take out the cirquitboard and sand off the inside of the face plate.
All I had to do was tighten the nuts problem solved.For real this time!
Click to expand...

My HD 350 had exactly the same fault. I tightened the pots - no fix! Opened the case to discover that the advice provided by EBS was complete nonsense - possibly a sales person giving this but not an electronics engineer.

The board in question is well earthed back to a separate chassis earthing bolt. There is no technical reason why the pots need to earth on the front chassis plate and mine was covered with overspray - its never been earthed that way, so no point sanding back the plate.

On closer inspection I found the fault. The board is a high quality machine soldered unit with the exception of the pots which have been hand soldered. It is a relatively thick board with the pots soldered from the bottom. For proper mechanical and electrical contact on these solder joints, the solder should flow through the hole in the board and onto solder rings both top and bottom. On my unit, the soldering was very poor and had not penetrated to the top ring resulting in poor mechanical strength. This board should not have passed a QA.

I re-soldered the pots and, surprise surprise, the amp is working perfectly. What I think has been happening in other posts is the small movement being made to these joints by either tightening the pots or removing the board (not sanding the chassis) is temporarily remaking the electrical connection. You may think the problem is fixed, however, without re-soldering the pots to make the joints mechanically sound, the fault could and probably will reappear.

P.S. Don't try this at home unless you have a temperature controlled iron, solder removal tool and board cleaner.
 

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