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Need help with DIN to RCA phono cable troubleshooting

Somehow, I am currently having an issue with an apparent ground problem with my DIN (female five pin straight connector) to RCA phono cable. The arm is a Dynavector 501 mounted on a custom plinth, supporting a Garrard 401 table.

There is a reduction in overall volume, bass frequencies are MIA, and this is all accompanied by a loud hum. I have tried doing a continuity test from a spare headshell to the ground cable, and RCA terminations. I can't tell where the ground was interrupted, I need guidance in how to test for proper continuity in relation to signal and ground leads. Also, I don't know where the shielding should be connected, so a thorough explanation will be needed.

 Thanks for any help that can be given.
 Regards,
 Dan
islandmandan
islandmandan OP
848 posts
 
Noromance, it's not the cartridge, I've switched carts, same result. I've found additional info at vinylengine.com, and will see where that leads to.

Thanks to all for your help.

Regards,
Dan
dover
1,165 posts
 
nandric
Dear Dover, Which method should be used to connect the XLR
connectors? Should the ground wire from pin 5 in the Din5 connector
be split in two such that each can be soldered to the pin 1 on the
XLR connectors? Or should only the (floating) shield of both
channels be connected to the pin 1 on the XLR connectors?
Nandric - for all phono both balanced and unbalanced the arm earth ( 5th pin ) should be a separate wire which you connect to preamp chassis. This simply grounds the arm itself and has nothing to do with the cartridge signal.

Floating shields on the signal cables should only be connected to earth at one end.
In the RCA's at the preamp end I connect the floating shield ( assuming a twisted pair plus shield construction ) to the chassis by cutting the connection to the RCA and soldering a tail for connection to the preamp chassis. This reduces the opportunity for noise collected by the shield to enter the phono signal in a single ended system.
In this arrangement you end up with 3 earth leads to connect to the preamp chassis - tonearm earth/ground plus left and right channel floating shield earth/ground.

XLR's have a separate -ve signal and earth/ground in a balanced system. Therefore you only need to ensure the shield is connected to the earth/ground pin which is already separated from the -ve signal. The tonearm end is left floating ( not connected ).   

totem395
196 posts
 
dover

In some instances a meter can burn out coils in a MC cartridge.  
I believe the above "in some instances" is when using an old style
needle type analog meter. Otherwise your ok.

nandric's avatar
nandric
3,263 posts
 

Totem  395, You both are right. ''Some'' (quantor) is true if there

is at least one object (aka ''entitity'') which satisfy given condition

(someone has stolen my car. Dover is the person who deed it).

''All Volt meters will burn out the coils'' is not true if there is one

Volt meter which does not burn out the coils.

To me an Volt meter is as important as the stylus brush. Those

are the se called ''neccesary  intruments''. Consider checking

those coils in advance instead of doing all the adjustment work

a priori and discovering afterward that the coils are defective.

Dover thanks. You are an excelent teacher.

 

atmasphere's avatar
atmasphere
7,068 posts
 

Should the ground wire from pin 5 in the Din5 connector

be split in two such that each can be soldered to the pin 1 on the

XLR connectors? Or should only the (floating) shield of both

channels be connected to the pin 1 on the XLR connectors?

The ground of the DIN goes to pin 1 of both XLRs.
@nandric , This:
Nandric - for all phono both balanced and unbalanced the arm earth ( 5th pin ) should be a separate wire which you connect to preamp chassis. This simply grounds the arm itself and has nothing to do with the cartridge signal.

Floating shields on the signal cables should only be connected to earth at one end.
In the RCA's at the preamp end I connect the floating shield ( assuming a twisted pair plus shield construction ) to the chassis by cutting the connection to the RCA and soldering a tail for connection to the preamp chassis. This reduces the opportunity for noise collected by the shield to enter the phono signal in a single ended system.
In this arrangement you end up with 3 earth leads to connect to the preamp chassis - tonearm earth/ground plus left and right channel floating shield earth/ground.

XLR's have a separate -ve signal and earth/ground in a balanced system. Therefore you only need to ensure the shield is connected to the earth/ground pin which is already separated from the -ve signal. The tonearm end is left floating ( not connected ).
-is mostly incorrect!

The tone arm is in fact the ground (which is the ground wire in a single-ended system). So the arm wand provides a grounded shield to the cartridge wires within. This continues through the DIN connection and splits to the shields of the left and right channels. At the XLR connection it ties to pin 1 which is ground). In this way the shield is constant from the cartridge to the input of the phono section.

Note that the ground is otherwise not part of the cartridge signal and should be ignored by the phono section in any event (otherwise Common Mode Rejection Ratio will suffer).

In a single-ended system it is advantageous to prevent the ground side of the RCA connection from being shorted to the phono preamp chassis (otherwise it is possible to introduce ground loops). So the only ground to be seen at the chassis should be the ground wire of the arm itself and not the minus outputs of the cartridge!
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