Wurlitzer 200A volume issue

[AceFrehley21]

Bought my Wurlitzer 200a, looks and sounds great however when I turn on the piano the volume nob doesn't change the volume, once the piano is on it's pretty much full volume and I don't know why. I'm assuming I just need to buy another volume pot for it, ideally I'd like to try and fix the one I have but tell me what y'all think

[pianotuner steveo]

It's likely bad, but you can try cleaning with contact spray. Unplug unit and be careful spray doesn't get into your eyes!

[sean]

I have never tried deoxit spray on anything other than a scratchy pot, and it is always only a temporary solution.  Caig Deoxit is difficult to find since the demise of all the electronics shops.  Oh, Guitar Center and Sam Ash show up on the Caig website, so maybe the local shops sell it - and it is easy to get online.

Oh but anyway, if the piano stays nice and loud while turning the volume pot, I would bet that the shaft is broken off, or that one or more of the wires from the solder terminals has broken off or been disconnected.  Replacing the pot is the best long term move.

Take a good look at the service manual posted by Chris and Fred at https://cdn.shopify.com/s/files/1/0666/2821/files/Wurlitzer_200_and_200A_Service_Manual.pdf?8872610067384662061

Pop the top off the piano and hunt around with a flashlight, and you might discover the problem.  And, uh, of course, keep your fingers off the high voltage while working inside the Wurly.

Sean

[Tim Hodges]

I'd suggest removing the pot, opening the tabs at the back and having a look at the resistance track.

I had a similar problem a while back, turned out all of the resistance track had completely gone except for some at the start and at the end.

https://www.facebook.com/photo.php?fbid=10100623476447867&set=gm.548003298929507&type=3

Rather than using deoxit I use some isopropyl alcohol and give the track a clean, re-grease the pot and re-assemble it. Worse can scenario if the track is shot just buy a standard CTS 10k log pot and  transplant the resistance track into the switch volume pot.

[pianotuner steveo]

I meant to use the contact cleaner spray to help determine if that is the problem, not a permanent solution. If it does a little bit to help, then you know you are on the right track. Replacing is likely the way to go. Are you experienced at replacing parts/soldering?

[Electrickey]

keep your fingers off the high voltage while working inside the Wurly.

How does one bleed the stored voltage in a Wurli?

[sean]

When you turn the wurly off, the 170 volts will dissipate slowly through the resistors in the power supply.  If you are foolishly adventurous, you can try to temporarily put a 10KΩ resistor across the reed bar input at the RCA jack.  I don't see any reason to try this.  You could get yourself the shock, or burn your fingers on the hot resistor.  In the tuning videos that I have seen, Chris seems to touch the reeds and pickups just seconds after turning off the piano.

With the wurly turned on, you need the high voltage to make the pickup work while you are testing.  Just don't poke your fingers under the hum sheild, or fiddle with the RCA jack.

I wonder how painful the shock from the 170V supply would be.  I know people have done it and survived.  However, I don't wanna be the guinea pig.

Sean

[pianotuner steveo]

Hahah, I learned the hard way, when I was a teen. I got this shock many times. It hurts, but it's different from an AC 120v shock.
It was over 40 years ago since this last happened, so I can't give more detail than that...

[David68]

Much more dangerous than the reed bar supply, which is very much current-limited through large-value resistors, is the exposed 120VAC on the back of the volume control.

Did the volume pot ever work? Is it possible that someone hard-wired it out of the circuit? I've seen stranger things.

[Tim Hodges]

Much more dangerous than the reed bar supply, which is very much current-limited through large-value resistors, is the exposed 120VAC on the back of the volume control.

I had a zap from that before, would not recommend.