Author Topic: Wurlitzer 140B  (Read 655 times)

Offline Proudfood

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Wurlitzer 140B
« on: June 14, 2018, 07:10:21 AM »
I recently bought a Wurlitzer 140B that puts out very low volume with a lot of hiss/white noise, other than that everything seems to function like it should. I noticed that what I think are resistors look like they are falling apart, see the first picture. Would that cause the hiss or is that symptomatic of another problem? I have some basic experience with electronics and could switch out the parts, just want to make sure I'm headed in the right direction. I also attached a picture of the whole circuitboard. Thanks for the help.

Offline Alan Lenhoff

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Re: Wurlitzer 140B
« Reply #1 on: June 14, 2018, 12:42:27 PM »
I can't help you track down the issues you mention. (Although I suppose the low volume might have resulted from someone turning down the gain control on the amp.)  But your photos suggest all your components are original, which makes them about 50 years old.  I would suggest a re-build.

Several years ago, I re-built mine, mostly following this https://cdn.shopify.com/s/files/1/0666/2821/files/Wurlitzer-140B-Rebuild_Schematic_a0f7a56a-ebaa-43f2-a518-519f29bd843b.jpg?5315161266642194721 plan from Vintage Vibe.  I replaced all the electrolytic caps (including the filter caps in the cans), the small transistors (look for extra low-noise ones) and the power resistors. I don't believe I changed the power transistors.  The before/after difference was dramatic.  People say the 140B amp is inherently noisy, but mine sounds great, and ought to be reliable for years.

The 140B is a great Wurli. It deserves an amp working at its best.

Alan
« Last Edit: June 14, 2018, 06:16:57 PM by alenhoff »
1974 Rhodes Mark I Stage 73
1972 Rhodes Silver Sparkletop Piano Bass
1978 Hohner Clavinet D6
1968 Hohner Pianet N II
1966 Wurlitzer 140B
1967 Gibson G101 combo organ
1965 UK Vox Continental
1954 Hammond B2; Leslie 21H; Leslie 31H
1977 Fender Twin Reverb
Vox AC30CC2X amp
(SEE THE COLLECTION: https://vintagerockkeyboards.com/ )

Offline Alan Lenhoff

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Re: Wurlitzer 140B
« Reply #2 on: June 14, 2018, 12:45:02 PM »
By the way, Vintage Vibe sells a kit with all the parts you would need:  https://www.vintagevibe.com/products/wurlitzer-140b-amplifier-rebuild-kit

Alan
1974 Rhodes Mark I Stage 73
1972 Rhodes Silver Sparkletop Piano Bass
1978 Hohner Clavinet D6
1968 Hohner Pianet N II
1966 Wurlitzer 140B
1967 Gibson G101 combo organ
1965 UK Vox Continental
1954 Hammond B2; Leslie 21H; Leslie 31H
1977 Fender Twin Reverb
Vox AC30CC2X amp
(SEE THE COLLECTION: https://vintagerockkeyboards.com/ )

Offline Ben Bove

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Re: Wurlitzer 140B
« Reply #3 on: July 12, 2018, 12:36:36 PM »
I would definitely agree that this amp is a candidate for rebuild.  The electrolytic capacitors alone (black) are well past the intended life expectancy.  Even if they were quality Sprague!

The question would be if you're comfortable removing components and soldering.  If not, I would recommend a rebuilding service.  It's straightforward enough with the rebuild kit, so any decent electronics repair shop or "guitar amp guy" could do a rebuild.
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Offline wolfpup

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Re: Wurlitzer 140B
« Reply #4 on: July 08, 2019, 10:57:26 AM »
Hi, all I'm new to this site  and i know this thread is a bit old,  but i have a 140B that came in for repair, has a loud hum sound that will increase with volume control.  i can hear the keys as well,   if i unplug the pickup  (RCA cable) the hum go's away and the amp is quiet as a mouse.   i plugged in a  MP3 player  and the sound is clean.    some kind of pickup problem ?

let me know what you think Also    i changed out all the caps already  but nothing else.


Offline Alan Lenhoff

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Re: Wurlitzer 140B
« Reply #5 on: July 08, 2019, 08:02:42 PM »
As an advocate of the "always try the simple stuff first" school of teching:

Is the lid removed from the piano when you hear the loud hum?  The lid on this model is painted on the inside with electrostatic shielding paint, which makes the lid a hum shield that protects the pickups from picking up external sources of hum.  These pianos will all hum like crazy if the lid is not in place. The lid also needs to be grounded. This is accomplished by tightening all its screws so it makes good contact with the grounding braided cable below the left side of the lid.  If screws are missing or the braided cable is damaged, or the lid is dented, it may not make good contact with this ground.

Alan
1974 Rhodes Mark I Stage 73
1972 Rhodes Silver Sparkletop Piano Bass
1978 Hohner Clavinet D6
1968 Hohner Pianet N II
1966 Wurlitzer 140B
1967 Gibson G101 combo organ
1965 UK Vox Continental
1954 Hammond B2; Leslie 21H; Leslie 31H
1977 Fender Twin Reverb
Vox AC30CC2X amp
(SEE THE COLLECTION: https://vintagerockkeyboards.com/ )