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Consoles => Magnificent Magnavox => Topic started by: robbo on February 05, 2018, 07:41:01 PM

Title: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: robbo on February 05, 2018, 07:41:01 PM
Hi All,

Could anyone please help me out with the specification for the 5 way speaker switch on the 233?  I busted mine and it's now precariously held together with superglue...it isn't going to last.

It looks like there are 10 wires on it, but I have no idea how to spec a replacement.  I've tried stuff like "2 deck 4 position" in ebay but come up with a slew of possible candidates.  I don't understand what it means by poles.  Since a lot of them appear to be sourced from Eastern Europe that makes it even more confusing...

Any assistance would be well received!

Thanks,
Rob
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: TC Chris on February 05, 2018, 07:44:31 PM
Maybe your best bet is finding a switch removed from a donor machine.  Wafer switches were commonly built to the specific requirements of a particular unit and may be very hard to replicate.  Try a request under "wanted"??

Chris Campbell
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: robbo on February 05, 2018, 08:09:45 PM
Thanks Chris, that's what my amp tech is telling me...likely custom made.

Apparently it's the same as in the Concert Grand.
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: electra225 on February 06, 2018, 01:30:43 PM
The speaker switches used in Imperial and Concert Grand instruments have double the number of terminals normally found in a stereo switch.  They have twin amplifiers in each channel.  A replacement switch will quite likely have to come from a parts donor, unfortunately.  They come up from time to time on ebay.  Good luck.
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: palegreenthumb on February 09, 2018, 09:23:24 AM
Usually, though, if you spend some time with the schematic, you can find a way to wire a standard switch to achieve the same functionality as a custom switch.  It might take more poles on a standard switch than on a custom switch, because the custom switches sometimes had funky contact pads that made contact with more than two terminals at once.  I guess if space is tight, more poles might mean a bigger switch that doesn't fit the space, but you don't know till you draw it all out, figure out what you need, and do some measuring and shopping.
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: TC Chris on February 09, 2018, 07:32:19 PM
Maybe the best bet is to try a repair of he original with epoxy.  Epoxy bonds are strong and have gap-filling properties.  It also sets slowly enough that you can align everything.  You can add various fillers--some, like colloidal silica, add structural strength.  Find the web site of Gougeon Brothers to learn about epoxy options and methods.

Chris Campbell
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: 19and41 on February 10, 2018, 03:59:51 PM
Here is the only place I know where you might find what you are looking for, or what you need to fabricate it.

http://www.surplussales.com/Switches/SWWafer.html
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: robbo on February 10, 2018, 04:27:48 PM
Appreciated sir.  I'll report back as and when we find a solution to this.
Rob
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: palegreenthumb on February 12, 2018, 12:26:10 AM
Spent some time this weekend trying to figure out how to map the Maggie's speaker switch to a standard off-the-shelf switch.

Think I figured it out.  And I found an in-stock switch at Mouser.com that should work (except, possibly, for the size, which may not fit the space, and the shaft length, which looks short).  Mfgr Pt# 44M30-05-2-05N, 5-position, 5-deck, 2 poles/deck, $98:  https://www.mouser.com/ProductDetail/Grayhill/44M30-05-2-05N?qs=sGAEpiMZZMvNbjZ2WlReYuoQqRoCNVYYoJmdr6og2BU%3d

Schematic below.  Note that you'd implement the circuit I've drawn twice, once for the horns, and once for the woofers.  The switch has 5 decks with 2 poles on each deck, which gives you 10 circuits.  You can lay them out any way you like.  I would probably use one pole on each deck for horn connections, and the other pole on each deck for woofer connections.  That way one side of the switch will be wired exactly like the other side.  Turn it around 180 degrees, both sides look the same.

Hope this helps.
Rodney
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: palegreenthumb on February 12, 2018, 01:40:59 AM
Oh, I see a similar 10 Pole-5 Throw (10P5T) switch at the surplus sales link that 19and41 gave above.

http://www.surplussales.com/Switches/SWRoMisc-1.html

Part number PA022-2947.  It's only $45.
Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: robbo on February 13, 2018, 06:54:53 PM
Thank you sir for giving this some thought and providing some options. 
The original switch is a 2 layer with 10 wires on, 5 per layer, paired up it appears.  So I was sneakily thinking that maybe something this might do the trick...

https://www.ebay.com/itm/Doule-2-Deck-Step-10mm-Mount-5-WAY-5-POSITION-CERAMIC-SELECTOR-ROTARY-SWITCH-D/381523031886?epid=2258156566&hash=item58d48b774e:g:1tgAAOSwq7JT6Yvq

A 5 x 2 rather than a 2 x5 .

But really I have no idea what I'm talking about or if it will work, just comparing pictures.



Title: Re: 5 way speaker switch for 1960 Imperial 1-ST233L?
Post by: palegreenthumb on February 14, 2018, 12:53:59 AM
Unfortunately that switch on eBay won't work, as far as I can tell.  It has only 4 poles (4 circuits), and I could not find a way to produce the same functionality as the original switch using only 4 circuits.  The best I could do was 10 circuits.  (Anyone else is welcome to double-check me, though... I don't claim to be Einstein.  I'd love to see a more optimized layout!)

The thing is, the original switch was a custom switch.  The contacts on it were able to make and break multiple circuits at the same time.  Also, as you rotated the switch, a single pad could make contact on one circuit, then a position or two later, make contact on another circuit.  A standard switch contact can't disconnect multiple wires from each other, nor can it operate in multiple circuits.  All it can do is make one contact at a time on a single circuit.

In order to make and break all the connections that need switching, I found I needed 5 circuits for treble and 5 circuits for bass.  That means a 10-circuit (10-pole) switch.

If you see only 10 wires on your existing switch, then maybe it's been tampered with previously?  The schematic shows 14 wires.  There are 2 inputs (Ch1, Ch2) and 5 outputs (Ch1/Right, Ch2/Left, Ext. Ch2/Left, Remote Ch1/Right, and Remote Ch2/Left) each, for both Treble and Bass.  7 wires for treble, 7 wires for bass.  14 total.

I have numbered the 14 wires in the following photo, in the same order that I listed them above.  1-7 are the Horn connections, and 8-14 are the Woofer connections.