On the Bench - Wurlitzer 145 Electric Piano

[DummyLoad]

piano came in last week and i'm just now getting to it (what a bum! :-\); the PT leaked a lot of tar, piano, amp still work but hums, as the owner proclaimed, "like room full of hindus". i fired it up and it does indeed hum, but i wonder how much of that is contributed by AC wires routed with the control panel volume and tone wires. the volume knob is also the pwr. sw... the owner replaced the 2 wire AC cord with an IEC, and grounded the chassis; he did a nice job.

can't find a schematic, or least one that won't cost $$, so i guess i'll just reverse engineer it if no one here can help out.

best guess mfg. date by part dating is around 1965.

the tube compliment is as follows:
1 6K11 - compactron - preamps
2 7868 - compactron - outputs - P-P config.
1 6CA4 - 9pin - full wave recto.

i'll post a schematic in a day or two... if anyone has any experience with these things, i'm all ears, and much thanks in advance for any info/advice.

--ISO

[LooseChange]

I had a similar one in the shop. Is the top cover off?
I found that the top is a huge shield and must be put in place and grounded otherwise you will hear lots of hum.

[DummyLoad]

I had a similar one in the shop. Is the top cover off?
I found that the top is a huge shield and must be put in place and grounded otherwise you will hear lots of hum.

top cover is/was on when tested... hummed louder w/o top. still bad with it on. the amp appears to be untouched except for the owner AC supply mods.

[LooseChange]

Same type of hum?
I ran a ground wire to make contact with the cover. try it.

[Dave]

If it were me, I would make sure that the owner knows that if the repair work is over about 30 bucks, then it will begin to exceed the market value of the organ.

Dave

[Jack1962]

Well ya know Dave the customers always right 

                                                 
                                                        Rock On

[RicharD]

>it will begin to exceed the market value of the organ.

Oh you are quite mistaken.  #1 it's a piano and not an organ.  #2 the 145 is perhaps the most sought after of the Wurlitzers, easily a $1500.00 board in decent condition.

[Dave]

I stand corrected. I guess I am used to seeing old organs being given away or sold for 25 dollars so often that when I see the word Wurlitzer and tubes in the same sentence, I just naturally think 25 bucks.

Dave

[John]

This is what I found. The attached png is what I downloaded from "quick view google docs" or whatever. Hope it helps, and it's what you're looking for.

http://www.ep-service.nl/joomla/downloads/Wurlitzer%20EP%20Manuals/Wurlitzer%20Electronic%20Piano%20Service%20Manual%20140-720.pdf

Edited to add this link too.

http://www.hallofelectricpianos.co.uk/

[DummyLoad]

This is what I found. The attached png is what I downloaded from "quick view google docs" or whatever. Hope it helps, and it's what you're looking for.

http://www.ep-service.nl/joomla/downloads/Wurlitzer%20EP%20Manuals/Wurlitzer%20Electronic%20Piano%20Service%20Manual%20140-720.pdf

Edited to add this link too.

http://www.hallofelectricpianos.co.uk/

john, thank you very much! 

[John]

You're welcome! Trying to give sumpin back for all the info I hog from here. ;)

[RicharD]

Way cool John THANKS!  The vast majority of us get a lot more than we can give here, but every little bit counts.  Best forum on the entire WWW.

-Richard

[DummyLoad]

Same type of hum?
I ran a ground wire to make contact with the cover. try it.

yours should have had one already - this one does. it's a piece of flat braid cable that's stapled to the right side top cover support riser right behind the control panel; the other end is soldered to the pickup coil shield.

[PRR]

> it does indeed hum, but i wonder how much of that is....
> dating is around 1965

Has it ever been re-capped?

Might be due.

Short V1 pin to ground near R28 10 ohms. If that kills hum, it's in the pickup or input networks. But I really bet it still hums. Replace all sections of C12 (big can).

[DummyLoad]

<Has it ever been re-capped?

no - all original ex. IEC socket w/ gnd pwr crd upgrade.

<Might be due.

definitely - c5, c14, & c16 are leaking. B+ cap is on order.

[6G6]

I had one.
I remember it always being a little noisy.

They are cool because if you play it softly,
it sounds pretty much like a piano.
If you really wail on it, it gets an overdriven tube growl
that doesn't sound like a Rhodes or anything else.

This whole thread makes me miss mine.

Listen to Jerimia Was A Bullfrog to hear one in action.
Damn, now I have that song stuck in my head!

[DummyLoad]

also:

ray charles: what'd i say
supertramp: nearly all breakfast in america album.
three dog night: mama told me & joy 2 the world
queen: best friend
pink floyd: money & time
rolling stones: miss you
allan parsons proj: eye in the sky & the voice

i love the sound of the wurlitzer...  :glasses1:

[simonallaway]

How about the intro to Sheep on Pink Floyd's 'Animals'? Is that a Wurlitzer? It's a beautiful sound.

[DummyLoad]

How about the intro to Sheep on Pink Floyd's 'Animals'? Is that a Wurlitzer? It's a beautiful sound.

sounds like a rhodes... ??

[simonallaway]

ah..ok.

I'm going to have to go and listen to the previously mentioned tunes.

[DummyLoad]

hum problem solved. after a cap job and re-assembly, i fired it up and still had an annoying amount of hum, although it was not as bad as before the cap job + now the PT does not overheat. i checked the grounding circuit for the cover and it is working. after looking at the layout, i decided to bypass the AC switch on the volume control - viola! dead quite now. i drilled the chassis and added a toggle power switch next to the IEC.

when i first plugged in the AC cord, i was greeted by a nice pop and flash - a piece of metal shaving from the drilling process lodged across the hot and ground pins in the IEC... i figured the blast with the air hose got all the shavings - doh!

interesting to note on this unit, the bypass cap for the 7868s was installed reversed at the factory. it was ballooned and open...

[LooseChange]

Great info and thanks. You would think putting 6o cycles right next to the volume pot would cause some noise. I've seen my share of flashes too.