BSR C1 stereo cartridge - connection confusion

[dazzlevision]

Hello,

In the process of refurbishing a BSR MA70 deck, I removed the cartridge and tone arm, complete with wiring to the tags trip on the underside of the deck.

Upon reassembly, I'm not sure the original way the wires were connected to the cartage pins was correct (I did make a note of it before disassembly).

I attach a sketch of the cartage terminal pins and the connection info embossed into the plastic case, but to my mind, the markings are ambiguous. For the R channel, the + is higher than the -, but for the L channel, the - is higher than the +.

Does anyone have a BSR publication showing the rear view and correct connections?

The numbering 1, 2, 3 & 4 of the four pins is my own and not embossed on the cartridge, for my reference.

I feel the connections could be either:

1 R-, 2 R+, 3L- and 4 L+

or

1 R+, 2 R-, 3 L+ and 4 L-

depending upon your interpretation of what the embossed markings mean (as the + & - markings are higher or lower than each other for left and right channels).

Your comments welcome, as if my connections are wrong, the phasing will be incorrect.

Regards,

Dazzlevision

['LIVEWIRE?']

Your second suggestion seem the correct one to me.

[Nicklyons2]

If you are in any doubt of your final wiring play a mono record and parallel the 2 cart o/ps - if they are out of phase you'll know!

[paulsherwin]

If you get the channels right and use the same phasing then that's all that matters. As Nick says, it should be pretty obvious if the phasing is wrong.

[dazzlevision]

Originally Posted by Nicklyons2

If you are in any doubt of your final wiring play a mono record and parallel the 2 cart o/ps - if they are out of phase you'll know!

Hello Nick,

That sounds like a good idea. If I play a mono record (I do have at least one mono LP), I should get very little output if the two channels are in antiphase and a greater output if they are in phase.

Many thanks,

Dazzlevision

P.S. Is it me, or is the marking on this cartridge ambiguous?

[Nicklyons2]

You wouldn't be wrong but many cartridges have, IMHO, horrid labelling e.g. the much loved Sonotone 9TAHC used to drive me scatty with the wiring to that plastic plug that fitted in its rear.

As Paul has said, for most cartridges the 'absolute phasing' is irrelevant but the relative phase of the 2 channels is important. With some cartridges the 'absolute phase' is determined by a case-earthed pin (usually only on magnetic types) ; stranger still I've seen cartridges where the case-earth bond is only on one channel - I assume the manufacturers believe the commonality of the amp inputs will ensure the other side will pick up an earth.

Cheers, Nick

[Nickthedentist]

Originally Posted by Nicklyons2

...I've seen cartridges where the case-earth bond is only on one channel - I assume the manufacturers believe the commonality of the amp inputs will ensure the other side will pick up an earth.

Yes, Nick, it's to prevent hum loops. Furthermore, some manufacturers (e.g. Shure) arranged the shield connection so that you can sever it with a sharp knife or sidecutters, thus separating the shielding from the signal wiring completely, to prevent hum loops via a grounded headshell.

Nick.

[Nicklyons2]

I'd never twigged that bit (re the two channels), though I have always been wary with the metal arm/headshell combo earthing; That type of 'bond' (shown on diagram) I've seen on quite a few carts; well worth pointing out,
Nick

[dazzlevision]

Hello,

I have carried out the test suggested by Nick Lyons, using a mono LP record. The difference between having the two channels connected in or out of phase (when the player is set to Mono) is profound, as predicted.

So, the correct connections are:

1 red R+

2 green R-

3 white+

4 black-

and the yellow wire goes to the metal tone arm, via a solder tag at the cartridge carrier end.

These are consistent with the terminations of the pickup wiring at the tag strip under the record deck (and the twin screened cable from these to the amplifier unit).

It's good to have a positive test to confirm this.

I can now proceed with the remainder of my restoration work (very little).

Many thanks for your comments.

Regards,

Dazzlevision

[ben]

Just the other day I did a similar thing to you with a BSR.
Red = R+, Green R-.
Black= L+, White L-

Yellow to arm tube, attatched at headshell screw.

[Nicklyons2]

Glad to hear you found the idea useful and it sorted your problem; and, for us all, we now have someone with the definative connexion arrangements for the C1 cart.

Just to re-iterate for those who are viewing this thread in general terms; this test is useful with any stereo cartridge BUT remember you do need to play a genuine MONO record.

Nick

[nigelr2000]

Having done this very thing the other day I found a stereo record sounded weird and had the vocals sounding like they were being sung in the next room that was a Sonotone stereo cart and the + & - were reversed to each other left to right ie + on top one side and + bottom on the other.

[nigelr2000]

I should add that was with L+R strapped together as it was a mono player

[dazzlevision]

Hello,

Here is a scan of a BSR leaflet on their C1 cartridge. Note that it doesn't show the electrical connections!

The leaflet is date coded 1964 and the body colour of the cartridge is white, but the three I have are black (later production, I think).

Regards,

Dazzlevision

['LIVEWIRE?']

As the connections (R+ -, and L-+) are stamped on the cartridge body, presumably they thought, maybe erroneously, that it wasn't neccesary to put further info. in the leaflet.

[dazzlevision]

Hello Livewire,

Possibly so, but I feel the markings could be interpreted in two different ways, as the + & - symbols are not "side by side", but offset "vertically", hence this thread.

Regards,

Dazzlevision

[vidjoman]

Your original post shows that 2 pins are close together and 2 further apart, just like the markings so I think it's fairly obvious what the connections are.

[dazzlevision]

Hello Vidjoman,

I could debate the matter further, but as the connections have now been accurately determined, there seems little point.

Regards,

Dazzlevision

[Nickthedentist]

Originally Posted by vidjoman

Your original post shows that 2 pins are close together and 2 further apart, just like the markings so I think it's fairly obvious what the connections are.

I tend to think the same... but it's nowhere near as clear as the marking on their later cartridges, so obviously people found it ambiguous.

Glad you got it going, Dazzlevision.

[ben]

Originally Posted by ben

Just the other day I did a similar thing to you with a BSR.
Red = R+, Green R-.
Black= L+, White L-

Yellow to arm tube, attatched at headshell screw.

Correction: in my above post, the white and black are inadvertently transposed! Dazzlevision had it right in his post next to mine in that the white is the left channel signal. Sorry bout that!