Author Topic: Wurlitzer picking up radio stations  (Read 504 times)

Offline theseacowexists

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Wurlitzer picking up radio stations
« on: February 13, 2021, 05:44:36 PM »
This is a new one for me. Been searching the internet to see if anyone else has had this issue, to no avail. Maybe someone here has had this happen to them?

I just fully rebuilt a 200 for a friend of mine. Fresh caps, resistors, new reed bar shield. It sounded great here when he came to pick it up. Clean signal, low noise floor. Until he took it home to his studio and it became a radio. Radio signals coming through as strong as the piano signal. I suggested moving it to a different spot to see if that helps, and it seems that there were some spots in the house that were a little better, but not by much. I took a look at it in person today, and it really was pretty bad. Re-tightening all the ground screws seemed to help, but it also seemed that dang near anything I touched would have a different effect on the noise. Even how close we stood to the piano seemed to affect it. He asked if I could line the lid with copper tape, so we did that and connected it to a ground screw, and that helped a little bit more. So it's more acceptable now, but still noticeable. When he got this thing, it didn't work at all until I rebuilt the amp, so we have no idea if it had this issue before, and the only other place we've heard it working properly without any radio interference was at my place. I did point out that he unfortunately lives less than a quarter mile from some massive radio towers.

Offline pianotuner steveo

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Re: Wurlitzer picking up radio stations
« Reply #1 on: February 13, 2021, 06:10:53 PM »
Well, there you go. The radio towers...
Are his receptacles properly grounded? I'm assuming he has a 3 prong cord?

Unfortunately, there may not be much else he can do other than move away from those towers....
Probably not feasible...
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...

Offline theseacowexists

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Re: Wurlitzer picking up radio stations
« Reply #2 on: February 13, 2021, 07:19:44 PM »
Yeh, and he just bought the house so he didn't really like that suggestion...

Who knows if the receptacles are properly grounded. Using a cheater plug made no difference, so I wouldn't be surprised.

Offline sean

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Re: Wurlitzer picking up radio stations
« Reply #3 on: February 13, 2021, 08:59:49 PM »
Build a small Faraday cage with chicken wire.

No.  I am being serious.

Basically build a small hut with a wood frame; cover it with chicken wire for walls, floor, and ceiling.  Yes, you need a door.  Ground the chicken wire, and you should be radio isolated.  I have worked inside one for audio diagnostic and repair work, and it works.

If it works, then tear down the drywall, put up chicken wire, and re-hang the wallboard.   Ha.  Not serious about that part.

Sean

Offline sean

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Re: Wurlitzer picking up radio stations
« Reply #4 on: February 13, 2021, 09:36:54 PM »


The smaller the holes, the more effective.   I mean that the minimum frequency that can penetrate the holes is related to hole size.
Smaller holes provide better sheilding - more low RF gets blocked.  If you want to block very high frequency EM waves, you need tiny holes.


Chicken wire vs. Aluminum foil:
https://www.youtube.com/watch?v=9M6h1U9jgWs

Ungrounded Chicken wire:
https://www.youtube.com/watch?v=nfC88nzqDWc

and a better discussion:
https://hackaday.com/2018/09/26/building-a-hardware-store-faraday-cage/

Sean
« Last Edit: February 13, 2021, 09:40:22 PM by sean »

Offline pianotuner steveo

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Re: Wurlitzer picking up radio stations
« Reply #5 on: February 16, 2021, 07:37:55 AM »
There is an inexpensive tester with lights that will plug into any 3 prong recepticle and it will tell you if the outlet is wired properly. They have 3 lights on them.They will light up different ways for correct wiring, open ground, reversed hot and neutral,etc. I think they are like $4 in any home store electrical dept.
 
He may possibly have an open ground.

Ok, they cost a little more- this one is $6 @ Harbor Freight

« Last Edit: February 17, 2021, 04:56:56 PM by pianotuner steveo »
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...

Offline theseacowexists

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Re: Wurlitzer picking up radio stations
« Reply #6 on: February 19, 2021, 07:16:33 AM »
We put a new volume pot in it and everything's back to normal. Go figure. He might have broken the old one when he tried lifting the lid with the knobs still attached as soon as it got home.

Offline pianotuner steveo

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Re: Wurlitzer picking up radio stations
« Reply #7 on: February 19, 2021, 02:09:58 PM »
More likely the carbon in the old one was just worn out. You are lucky that you found it fairly quickly.
I had a Wurli with a worn vol pot once and it caused a loud hum at any volume.
I went crazy replacing parts....
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...