Switch for Neumann PV76
« on: August 08, 2020, 03:57:22 AM »
Is anyone familiar with the gainswitch in these?

I am repairing a Neumann PV76 with a faulty gainswitch. The transparent plastic parts have gone brittle and broken and at least one spring is missing. I guess this is a common problem with these old switches. Is there any way to repair the old switch?

If not, I am looking for a new switch. I have a little trouble understanding these big rotary switches, so a little help finding the right part would be much appreciated. This is what I know: there are 11 positions on the switch (I think it might be a 12-position switch with a stop for only 11 positions). There are two "layers" - I guess that is what's called wafers and as I understand it there are two poles for each wafer.

I think an Elma 04-2213 as what I need. There is an overview of Elma switches here and I found it in a shop here.

There is a schematic here and here

When I look at the switch, I get a little confused because it looks like there are four poles on each wafer. At least on the bottom part of the switch, I see four leads going to solder lugs in the middle part of the switch (not the rows around the edge). But maybe only two of these are actual poles and the others are start- or end points in the row?

I have attached a photo of the faulty switch.

If anyone can help me decide which way to go with this, I would be very pleased.



Re: Switch for Neumann PV76
« Reply #1 on: August 08, 2020, 04:00:33 AM »
I have an other PV76 that is working well. This one has a different type switch - I have attached a photo.

gyraf

Re: Switch for Neumann PV76
« Reply #2 on: August 09, 2020, 04:52:21 AM »
..det ligner en elma04 du allerede har dér i den defekte - tænker at det da ville være det sikreste bare at udskifte de dele i switchen der er i stykker. De er helt modulære, til at skille ad, og alle stumper ka' fåes fra Elma (inklusive alternative torque-springs) - eller transplanteres fra en ny/brugt switch fra skuffen..

/Jakob E.
..note to self: don't let Harman run your company..

Re: Switch for Neumann PV76
« Reply #3 on: August 11, 2020, 07:15:20 AM »
Det er desværre ikke den samme type som den nye 04. Jeg har været i kontakt med Elma, og de siger, at de stoppede med at producere den model for 20 år siden og har ikke længere reservedele. Så det er nok enten noget med at finde en tilsvarende gammel Elma og transplantere fra, eller punge ud for en ny type 04...

Re: Switch for Neumann PV76
« Reply #4 on: September 15, 2020, 05:53:05 AM »
I bought this Elma type4 switch: https://www.don-audio.com/Elma-Rotary-switch-Type-04-Eyelets-2-Wafers-4-x-11-Shorting-15-04-2213
It turns out that the shaft is a little too long. Does anyone know if I can just shorten it by sawing off the last 5-10mm. or will I run the risk of destroying something internally?
Kind regards
Lasse

gyraf

Re: Switch for Neumann PV76
« Reply #5 on: September 15, 2020, 08:22:54 AM »
Akslen kan du save hvor du vil. Men bøsningen/gevindet er ikke sådan lige at forkorte hvis det er dét du mener..

/Jakob E.
..note to self: don't let Harman run your company..

Re: Switch for Neumann PV76
« Reply #6 on: September 15, 2020, 02:11:45 PM »
Tak. Det er bare akslen, der skal forkortes lidt, så den får en tur med nedstrygeren   :)

Youngwhisk

Re: Switch for Neumann PV76
« Reply #7 on: September 15, 2020, 02:55:41 PM »
Tak. Det er bare akslen, der skal forkortes lidt, så den får en tur med nedstrygeren   :)

A Dremel with a cutoff wheel will put less stress on the shaft and pot.

Gold

Re: Switch for Neumann PV76
« Reply #8 on: September 15, 2020, 04:46:55 PM »
The key is to put tape where the shaft meets the bushing so no debris gets inside. The other key is to put the shaft and not the body of the switch in the vise. This avoids undue stress on the switch or pot. A cutoff wheel or a hack saw works.

gyraf

Re: Switch for Neumann PV76
« Reply #9 on: September 16, 2020, 02:35:04 AM »
..yup, you're off course right, take care when sawing..
..note to self: don't let Harman run your company..


Re: Switch for Neumann PV76
« Reply #10 on: September 16, 2020, 08:34:29 AM »
Thanks for pitching in everyone. I've done the cutting, and everything went smooth. Now it's time for soldering everything in it's right place (hopefully)  :P


 

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