Cleaning/Replacing switches of Klein & Hummel UE 400?

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Eurocide

Active member
Joined
Nov 17, 2005
Messages
35
Location
Germany
Hello,

I've shot a good Klein & Hummel UE 400 for only 350,- bucks at eeeee*y.
It works very fine but the main bypass switches tend to loose contact when touching them once in a while.

Is there a possibility to clean the switches or should I replace them?
 
There are two "circular turning" 2 way switches.
Similar to the ones, that are used in the original GSSL.
I haven't opened the device yet.
 
Ok, rotary switches. Most likely not PCB mounted (isn't the UE-400 a transistor EQ). Just find a switch that fits the hole/space in/behind the panel and you're rolling. Alpha, Elma, Grayhill.. if the audio is taken through the switch (it's not controlling a relay or anything) I suggest you invest in a good switch and not a Lorlin. :thumb:
 
From the schematic, it looks like a double-pole double-throw switch:

http://www.gyraf.dk/schematics/K&H_ue-400.gif - look at module B-246.

Jakob E.
 
Unfortunately, I figured out that the noise doesn't come from the main bypass switch.
It is the 2nd bandpass module of the left channel.
So, the problem seems to be a bit more serious.

Symptoms:
Permanent scratching/fuzzy noise when Gain is set off its center position (not while moving, so the potentiometer itself seems to be OK)

Noise increases in either Gain position - positive AND negative.
With negative values the noise sounds filtered by the given frequency, with positive values the noise is boosted.
In "Lin" (=center) position, no noise occurs.
Noise level is around -65dbFS.

The signal itself is not affected, like audible distortions a.s.f.
Also the frequency adjustment controls seem to be working fine.

Because I am a beginner in DIY-Audio, I don't know which component could be responsible for the noise.

Thanks for any help!
 
:cry: Sniff! It's getting worse.
After two working days with the K+H the whole right channel produces a lot of pink noise sometimes. I traced the possible failure down to the right summing module.

Noise occurs only when main bypass is switched on and only sometimes.
After switching off the device for a minute everything returns to normal again.
Maybe a loose contact or a damaged component - I don't know!

Boy oh boy, and I thought I made a good deal...

Any help would be very appreciated!
 
I had a few broken bands in our UE400 and UE200s and couldn't find the fault. After all I exchanged all tantallums, the FETs and the opamps. works fine again.
 

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