651 Wiring

[Chris Simon]

Hello all:

           Does anyone know how power is distributed to all the light bulbs in the switches in the 651 Master section? In particular, where does the -18 volt line on the blue wire terminate? I'm working on a client's 4000G, and many of the switches don't light up, although they do perform their switching function. Also, does anyone know the type and gauge of the red and blue wires coming up the the back of the switches? I believe it's 24 gauge Kynar wire, but would like to know in case I need to rewire.

Thanks in Advance,

Chris

[jimlfixit]

Hi Chris

The power for the 651 comes from the circuit breakers/switches on the connector panel through one of the two 104 way Mrac connectors that screw into the rear of the 651.
As far as I remember, the red and blue wires (+18 and -18v respectively) could well be 24 awg Kynar wire although they may be the smaller 26 awg version instead. SSL used both sizes.

Hope this helps from Jim Lassen, Marlow, Bucks, UK.

[Chris Simon]

Thanks Jim. As it turned out, I didn't need to rewire any of those lines; the fault was a -18 volt line that had broken off one of the switches and disconnected all the switches further down the chain. I did buy some 24g wire, as the 26g stuff looked a little skinny.

Chris

[jimlfixit]

Hi Chris
Glad you sussed out the 651 power wiring problem. After many decades I guess some of those solid kynar wires in particular, would become brittle and snap off. It that involves the power wiring, it is even more important of course.
The 26 solid awg version should be fine due to the current requirements but a 24 awg replacement would be better of course.
SSL wired the 651 on looming jigs and used the 26 gauge as it would take up less physical space and the wires would be easier to form.

Back in 1980, I applied for a job at SSL to build the 651 and didn't get it. A few weeks later, a wiring person fell down a lift shaft (more on that at some point later) and John East, one of the main designers there (and still a great friend who now builds retrofit guitar pre/amps for some big names) called me to replace that person. I got the job and stayed there for 7 years from 1980 to 1987.

If you need any SSL wiring done (DL's or 25 way D's etc) get in contact even though you are based in Canada (I am in Bucks, UK).

[Chris Simon]

Hi Jim,

         Thanks for the kind offer of help. I am, however, well versed in the art of DL wiring, having pinned and depinned many DL's, both on the two SSL's we have, and on our Mytek headphone system. I used to fear going into the 651, but no longer. A question though; is there a preferred part for the guides that hold the 651 cards in place at the bottom of the module? I have a few that are past their prime. Thanks in advance.

Chris

[jimlfixit]

Hi Chris
Although I worked at SSL for 7 years (1980-87) I wasn't involved in the 651 much and have no idea where they bought those card guides from. Are they black or blue from memory? Maybe Recycled Audio in the UK can help with this.

SSL bought a lot of their rack type stuff from Vero but the name may have changed since then.

Hope this helps a bit and good luck in your search.