33 noisy/faulty/loud switches, solved!

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05-Jun-2019 07:04 PM

Generator

Generator

Posts: 7

Recently restored a very rough 33. This one had been suffering moist conditions, rusty casing and corroded knobs.

Applied all the usual: Dada upgrade, replaced all resistors in the phono-section, etc. Discovered I had a serious issue with loud/faulty switches. Speaker cones jumping, channels coming and going, only occasionally would the turntable even make any sound at all!

Now, Dada says these are NLA, irreparable, and they will sell you a used board subject to availability. Not good enough for me... Quad says they are very good, and serviceable?! Besides, nobody answers when I email Dada.

In the bronze-foundry where I work, we sometimes clean off oxides with citric acid. Realizing that I'd have to remove the switchboard no matter what, I decided to treat it to a bath.

Soaked the entire board overnight in a relatively mild solution, then added a bit more acid the last two hours. The buttons recieved a bit of excercise along the way. Then cleaned it off with warm water and a soak in isopropyl alcohol. Blow dry with compressed air.

Reattaching the board was quite fiddly; a lot of wires, but I had photos just in case.

The result was overwhelming: everything works completely and without fault. There's even a "snappier" response to the buttons.

So if you've got the switchboard blues, a bit of acid will take care of it. By the way, the switches are serviceable and come apart to be cleaned. It's just very fiddly. There's a manual in the download section. I took one apart after my treatment and it was indeed squeaky clean. Before you ask: citric acid is readily available almost anywhere. It is often present in coffe-machine descaler.

Best of luck

Viggo from Malmö, Sweden


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13-Dec-2019 07:12 PM

Christophe59

Christophe59

Posts: 2

Hi Viggo,


Can you please give us a hint about the acid dilution that you used?

Would hydrochloric acid work as well?

I just tried contact spray and wait til tomorrow before I connect the 33 to the mains.


Thx

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19-Feb-2020 06:15 PM

Generator

Generator

Posts: 7

Citric acid is definitely the best. It's quite mild. You're cleaning off a layer of oxide from copper or silver. Citric acid only dissolves the oxides, does not bite the metal.

Don't use hydrochloric acid, this is strong stuff.

I used one little coffe-machine tab for about 3-4 litres of water. Later, on second thought, I added another half;-)

So maybe two spoons of citric acid to 3-4l.

Hope this helps. My 33 is still happy, though I am considering options for replacing the volume-pot...

Regards, V!

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19-Feb-2020 08:02 PM

Christophe59

Christophe59

Posts: 2

Thanks Viggor,

the contact spray worked quite nicely as well; at least with my 33.

The only thing I'd like to replace is the volume poti with the power switch. But I'm thinking of replacing it with an ALPS poti and mounting a power switch to the rear side of the housing.


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20-Feb-2020 04:13 AM

EJP

EJP

Posts: 1742

A replacement volume pot with integral mains switch is available from the Webshop here.

EJP

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