Uturn audio-no sound

[aragorn723]

I just changed the cartridge on my Uturn Orbit, and now don't have any sound at all with the new cartridge.  Only sound is a loud humming sound.  What could be wrong?

Dave

[Thermioniclife]

Is there a ground wire connected the phono preamp. Terrible buzz is an indication of a poor or no ground.

[aragorn723]

There is no ground wire from the Uturn to the phono preamp , it's internally grounded.  I'm wondering if maybe the cartridge wires aren't hooked up right?  The London cartridge has color coding on the pins. 

Red-right channel positive
Green-right channel negative
White-left channel positive
Blue-left channel negative

The wires from the Uturn had these colors, so I just matched red to red, blue to blue, etc.  Maybe Uturn is using a non-standard color scheme?

Dave

[Thermioniclife]

I am not familiar with that cartridge but you need a good ground to the pre. does the cart mounting tabs have a conductive pad on them? If so you can try a small gauge wire connected to one of the cart mounting screws to the phono pre as a test. It's been decades since I have had a turn table and vinyl. Perhaps you could call the manufacturer for advise.

[oguinn]

U-Turn has really great customer service. I’d email or call them
 

[galyons]

Decca cartridges are more than a bit quirky.  I  think they are very poor choice, and/or recommendation, for vinyl newbies.  They literally have almost no suspension, are not easy to align properly and are very easily fatally damaged. (Don't ask me how I know!)

The original design is ancient. It is a three wire layout. The L &  R channels share a common ground. The actual cartridge is shoved into a rather rough plastic carrier mount that ties the grounds to the common 4 pin configuration. Sometimes it works. Sometimes....

 I would go to the Lenco Heaven forum cartridges section and look for Decca threads. It is the best source of community knowledge on these cartridges.

Cheers,
Geary

[aragorn723]

Thanks all.  Gonna start with Uturn.  Was hoping there was something simple I overlooked, but maybe they can help troubleshoot the issue on the turntable side.  The London distributor has been very responsive too, so that might be a good option also.  Hopefully it's not the cartridge.

Dave

[Adrian]

I used to have a Rega TT and they do not have an external ground wire.
Here is what I found on their ground connection:
"Rega grounds the tone arm tube to the phono preamp using the shield of the left channel of the phono interconnect cable. It might be the connection of the outer shell contact of the IC to the RCA jack on the phono preamp maybe corroded and not making a good low resistance connection. You might try unplugging both the L and R channel ICs from the phono preamp jacks and plugging them back in repeating the process several times. That should clean the connections.
If that doesn't help you could install a small gauge stranded insulated ground wire from the TT tone arm to plinth support nut on the under side of the TT and connect the other end of the ground wire to the ground lug on the phono preamp."

Maybe this will help.

[aragorn723]

I just realized there is something I forgot to mention.  When a record is placed on the turntable and the stylus is lowered, there is some sound.  If you place your ear very close to the cart some sound is audible.  Maybe there is a gain issue in addition to the ground?  Did some research on my phono stage too, and there is a level control (normally I don't see this as the phono stage is tucked out of sight).  I'm wondering if maybe the cart is working after all?

Dave

[oguinn]

I think that's just the sound the stylus makes as it runs along the grooves. Probably if you turned the turntable on without the preamp you'd hear the same sound near the surface of the record. That doesn't really tell you much.

[aragorn723]

Gotcha.  Always wondered what that sound was.  Uturn emailed back and wants pictures.  They are determined to figure this out.  Everybody loves a good problem to solve, on wait no, that's just engineers lol.

Dave

[oguinn]

U-Turn was great when I had their table in my last house. I did have a grounding issue that they solved by running a wire from the Pluto pre-amp I was using to the screw in the wall outlet's faceplate. That cleared things up for me.

[aragorn723]

Just played with the volume knob, no change in music output regardless of position.  Hopefully Uturn can figure it out.

Dave

[aragorn723]

The verdict from Uturn is the turntable is fine, but something is wrong with the cartridge.  Waiting to hear from the distributor in the UK to see what to do next, think I can hook up my old cartridge for some weekend listening?  Thinking this will be a RMA situation.

Dave

[Paul Birkeland]

Yes, put your old cart back on.