Internal phono cable - amplifer which end to sheild braid

[MaccAu]

Hi,
In short, using only Phono1 with my Technics SU-V9. Phono2 rca sockets appear to have continuity with the return - i have no use as there is no room for a second turntable.

To do the internal phono cable between phono pcb and the tiny output/tape pcb, i thought a normal interconnect with the braid shield attached at the source end ( phono pcb) only. I use Van Damme cable, my version is better than the photo one as it has a very dense braid.

? would this be the correct way to go about it?

I would do the same for the left channel

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[scottjoplin]

How is it connected at the moment, is it causing a problem?

 

[MaccAu]

Thanks for the reply Scott. I changed the cable so, i am trying to think how I did the V8s in the past i used the above set out i think. Maybe is best to treat it as an RCA cable and maybe attach sheild at phono pcb? and just the blue cable (for right channel) to the return of the RCA socket

 

[scottjoplin]

Your picture shows the screen connection on the phono PCB, is it shown on the output pcb, and are the socket insulated from the chassis?

 

[MaccAu]

Yes, they are shielded both ends

my issue now is to use the 2 core cable and connect shield to the blue cable at both ends and for the left connect the red to shield both ends

OR
get new sockets and just connect up phono2 as per manual. The above would be easier , as i have rather large rca sockets Furutech for Phono1

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[scottjoplin]

Ok, it threw me that it appears both phono inputs are carried by one screened cable for each channel, is that correct?

 

[MaccAu]

yes, that is correct - each channel for left and right of phono1 and 2

you'd think that could cause more crosstalk. I have to check how I did my Technics SU-V9 i was sure it was 2 core cable and shielld and i used just phono1 (omited phono1) it was just like an ordinary interconnect

 

[scottjoplin]

It does seem an odd way to do it. Now, an ordinary interconnect is a single core with a shield, but you want to use a shielded twisted pair (STP)?

 

[MaccAu]

thanks Scott
A twisted pair and shield the cable

I had a look at the V8s, it appears i have shieled both ends using one of the twisted pairs as the ground /return soldered on to the shield and the other as the signal?

would singe core be better, i chose this particular Van Damme cable as its only 50 compactiance at the core to core, and 95 shield to core. I could use only one of the twisted cores per channel? and keep the shield separate

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[scottjoplin]

For an unbalanced connection, single core coax is usually the best, and certainly for an internal connection. Occasionally unbalanced interconnects are made using STP with the shield connected at one end only.

 

[MaccAu]

Thanks Scott.

Yes back in 1982, maybe that was how the cabling was done internally. I thought also shield one end, a well shielded coax, Van Damme has those also in their range.

 

[scottjoplin]

Not according to the service manual. The coax shield is also the return so must connected both ends

 

[MaccAu]

Thanks , yes, that is how it was, i pull the original cable apart

It consisted of a drain wire and 2 core non twisted cables wrapped in foil ( later models) the V9 and V8 spiral tinned copper/ foil and twisted cores