Wurlitzer 1600 Help cartridge modification

I am working on restoring a wurlitzer 1600 juke with the 518 wurlitzer mono tube amp.

I have recapped this amplifier.

I need information on modification from zenith cobra cartridge to a magnetic cartridge

Sinve nothing has been added from here, I am consolidating all information to my original restoration thread locateded here: [forums.arcade-museum.com]

Hello LovelyCoCoNuts,

In the archive there is a description how to modify to a ceramic cartridge.
[www.jukebox-world.de]
Keep in mind that a new tone arm might be needed because of the larger size of a replacement cartridge. Also the Cobra wire needs to be replaced against a flexible tone arm wire.

When using a magnetic cartridge a pre-amplifier is needed as well.

After doing the modification the tone arm weight has to be adjusted. I would go for a magnetic cartridge which is good for a pressure of ca. 3 - 4 g.

Regards - Hildegard Stamann

P.S. Of course one should consider whether the jukebox should be left original or not in advance - even if all could be reversed at a later date.

Hello LovelyCoCoNuts

Why do you want to eliminate the Cobra system? It was the source of the legendary Wurlitzer sound. I would recommend to keep this sound as long as possible. New Cobra needles are still available.

If you still want to use another pickup, I can give you some hints. I think that a magnetic pickup will not work well because the needles have too much compliance. Ceramic pickups should be possible if you can mount them in the tonearms.

Another problem is the switching. The wiring to the Cobra cartridge is not sensitive to hum, as opposed to all other pickups. The switch is not shielded and this could cause hum. It may be possible to omit the switch and to connect the two pickups in parallel. But I never tried it.

Finally, the amplifier is to be modified. I have not yet modified a 518 - amplifier, so I can only give general hints. The first tube (6J5) is the oscillator for the Cobra system and is no longer needed. The tube can be removed as well as the resistors R2 and R3. The wiring from the input jack comes to the connection point of R5 and R6. R7 is certainly too low-resistance. This resistance is the load on the pickup. Depending on the pickup used, it should be on the order of 500K to 1M. The value is to be determined by experiment.

I hope this will help you.

Best regards - charly49

Hello LovelyCoCoNuts,

Could you find out anything in the meantime?


Regards - Hildegard Stamann