Wurlitzer 1100

geschrieben von - posted by Oliver Stamann 
Wurlitzer 1100
01.11.04 08:11
Die nachfolgenden Beiträge sind aus dem alten Forum (bis zum 31.10.04) übernommen. The following posts had been taken from the old forum.

Autor: Bo Korposoff 
Datum:   10-22-04 13:53
Perhaps anybody could help me with two problems I have with my Wurlitzer 1100. The first problem is that I have a small hum in the speaker when I play. The amplifier is rebuilt and I think the hum depend on when the motor runs. Do anybody know if you could do anything about this.
The second problem is that sometimes when I made a selection nothing happen. If I try again everything could work normal. I think the problem can depend on the selection unit and the coils but I don’t know how to fix this problem.
Regards – Bo

Autor: axel rosenberger 
Datum:   10-28-04 16:06
Hello Bo
To your first problem:
If you disconnect the motor, the hum is not longer present?
Do you use a 50Hz gear set or a cycle converter from 60Hz to 50 Hz?
Is it an electrical hum, which comes from the amp. (maybe a bad ground connection anywhere) or is it a mechanical hum, that comes from the motor over the turntable to the needle and is amplified (in that case should be the hum not longer present if you lift the tonearm by hand during operation)?
To your second problem:
First of all: Be sure that every selection from the keyboard is registerd by the electrical selector (you can see a small pin moving when a selection is made).
If everey selection is registered by the selctor you should check
the small micro switch on top of the selector.
If any selection is made, a wobble plate inside the selctor is moved which closes that microswitch.
It can happen, that the microswitch is not closed when some selection are made.
You have to adjust the microswitch again so it closes a little bit "earlier" (but not to early, otherwise the mech. runs without a stop and plays one record after the other from higher numbers to the lower numbers).
Adjustment of the microswitch is described in the 1100 manual.
Best wishes - Axel

Autor: Bo Korposoff 
Datum:   10-30-04 10:17
I have find out that I still have the electrical hum in the speaker when I disconnect the motor. Sorry I gave you wrong information I was so convinced it was the motor because the amplifier is recapped recently and I have also replaced all tubes.
The hum sounds like it would be a 50 Hz hum. I have an isolating transformer (220V to 110V) close under the amplifier. Perhaps it could be the reason to the hum. I will check this later today. The line connection to the jukebox is without ground wire so I suppose it’s not possible to ground the jukebox?
Best regards - Bo

Autor: Bo Korposoff 
Datum:   10-30-04 18:59
I have now checked and the hum doesn’t depend on the isolating transformer. I have also notice that the hum is not depending of the volume. If I turn of the volume, I could still hear the hum. I have rebuilt the amplifier but not the Volume box. Could the hum depend on bad capacitors in the volume box? Is it anything I should check in the junction box?
Regards - Bo
Re: Wurlitzer 1100
01.11.04 14:06

maybe one of your 6L6 is bad ? (They should be in similar condition.)
So try with another one or use a new couple for a trest...

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