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Printed Circuit Boards by Emissionlabs.

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EE50 and EE51 Fault finding hints

This MC unit should work right away, and problems should not occur. If there is hum however, there is a problem in your set up, and the root cause must be found somewhere outside the EE Board. The combination of record player, MC Box, phono pre amplifier, and power amplifier, with all it's cables, can be complex. To find what causes the hum needs some local testing, for which the EE51 board has some special possibilities. It can not give a final answer to everything, but a good hint may well result from it. So if one of the tests in positive, read in the comment box, what MAY be the cause.

Music will not play with these settings. This only for testing, in case there is some hum, which is not caused by EE board.

  • >> First, write down the regular settings you had now, for A, B, C, D, H1, L, H2, GND!
  • Keep all equipment and cables connected.
  • The settings below here, must be done for both channels together.
For Test only
A, B, C, D
H1, L, H2
GND
Comment
1
 If hum with this test setting, the problem is more likely in the PHONO amplifier itself.
All Jumpers In
None
None

This setting does two things.

First, it disconnects all transformer connections at the primary side, both signal and ground. Like this, absolutely no signal can be passed into the transformer. Also errors from a ground loop are stopped this way.

Second, the phono amp input is shorted to ground.

In this condition, remaining hum is generated by the pre amp itself.

A very small chance remains it is caused by a ground loop in the cables connecting pre amp to the power amplifier, but because ground is also cut off (Ground Jumper is open), this is unlikely.

2
 If inserting and removing the GND link will make hum come and go, there is probably a ground loop somewhere in the external cabling.
A, B, C.
None
In and out
 Primary transformer side is also fully disconnected here, but now the pre amp is connected, with damping added. Adding and removing the Gnd Jumper, will connect or disconnect the record player ground. If this test is positive, there may be a ground loop in the record player cabling.
3
 If hum with this test setting, there may be external field radiation into the MC Transformers.
None
H1, H2
None

Though the Lundahl transformers are probably the most hum insensitive on the market, low cost mains transformers of the amplifiers are sometimes terrible sources of magnetic field.

However such fields have always a source, and you can find it easily. If this test is positive, try placing the MC box further away from the equipment which radiates the hum, or rotate the MC box 90 degrees. This is not intended as solution, it only proves, if so, where the problem is coming from.
4
When done:
Do not forget to restore the original settings of the jumpers :)

 

When the MC box is finished: Burn-in is NEEDED!

There is so much voodoo talk in the internet, even about burning in DVDs, and gold plated mains fuses. Feel free to believe it, and it doesn't harm you. MC transformers however always need a burn in. This is strange, no burn-in guru talks about it. So we do it here :) This is not Lundahl specific. All magnetic materials adapt to the orientation of the earth magnetic field if they are tapped on. You can try it with a large iron nail. Like 7cm length. Place it in front of you, and point it to the Earth's North Pole direction. Firmly tap on it with some a metal object. Then, hang it balanced on a thin cotton wire, and voila: you just made a nice compass. This is how easy materials can become magnetized by the earth magnetic field.

The transformers during shipment, are rattled in the truck, the package is kicked around by the post office, and perhaps you dropped a transformer a bit too hard, unaware you should treat them GENTLE. This may cause some small magnetism in the transformer, which gives a small unlinearity. Nobody can say if your transformers were dropped during shipment, or were close to magnetic fields. People ship Neodyme magnets by post too. This magnetism inside the core will go away, just by using them for some time. The transformers are literally burned in during production, as heat removes the magnetism too. So they are shipped free of magnetism, but the journey may (sometimes) add some small magnetism.

It is not possible to express the burn in time in hours, but it is in the range of a few weeks of normal use. Did you hears sometimes people say, their transformers improved sound during burn in? Well this was no voodoo, it was real, and this was the reason.