Author Topic: Cleaning Power Transformer Bell Out Of Strange Dirt  (Read 1740 times)

GibsonGM

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Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #20 on: February 19, 2020, 05:25:44 AM »
That is a SUPREME job, sarakisof!!  Very nicely done!  Very good that the trafo company helped you out!

The very slight voltage variation, I would not worry much about.   Your next project, however....is to replace all of the electrolytic capacitors, which are now getting VERY old.  They dry up and degrade with age.   Audiophiles change them in 10 to 15 years, many times.  Yours may be 50 years old, ha ha.   I see from reviewing your original post, you know about this.   Good luck, it should not be a difficult job.

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antonis

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #21 on: February 19, 2020, 06:03:02 AM »
Does the ancient spring reverb still works satisfactorily, Sofoklis..??
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"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

duck_arse

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #22 on: February 19, 2020, 09:24:44 AM »
Quote
What do u think guys ?

I think it's a good story well told. and a nice outcome. where the hell do you keep finding these organs?
"I wish my brother - um, George? - was here, Bob. There's only six now Sarge; we're good to go."

tubegeek

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #23 on: February 19, 2020, 11:07:01 AM »
What do u think guys ?

I think it's all about the friends we make along the way, and making friends with a transformer shop is as good as it gets!
"The first four times, we figured it was an isolated incident." - Angry Pete

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pinkjimiphoton

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Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #24 on: February 19, 2020, 01:58:12 PM »
wondering if the dust was just old dry rotted potting wax from the transformer?
also, old insulation in these sometimes either evaporates or turns to a nasty sticky goo. as the stuff evaporates, the fumes seem to break down other stuff made of plastic in these.

i have a combo compact if ya need parts that needs a home. if interested for a fair price, pm me. the one i have DID work last it was plugged in, tho there's a note "Stuck on" i am assuming is likely a bad cap or something. i was gonna just part it out for germanium, but better to recycle if someone can use it.
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sarakisof

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #25 on: February 21, 2020, 02:36:33 AM »
.....
« Last Edit: February 21, 2020, 04:35:05 AM by sarakisof »

sarakisof

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #26 on: February 21, 2020, 04:14:28 AM »
Your next project, however....is to replace all of the electrolytic capacitors, which are now getting VERY old.
Take a look at my last post's pics, i am already in the proccess of doing this. Have replaced all electros on tube power and preamp section and some others in one or two problematic tone generator cards alongside with some faulty SFT 352 Germaniums - replaced by Soviet ΜΠ20Α PNPs, after having geofex tested them out (thats why u see markpen dots on - i hfe grade by marking them).
I use to repair vintage combo organs, i love them. In the past, i used to make pedals, diy tube amps, vintage condenser mic clones and stuff like that, guitar/bass stuff mostly, but since i found my first combo organ four years ago, the Elka Panther 300, i then felt in love with them. I learned to play keys and blend them into my music, because i was fixing them... Now i play more keys than i play my guitars and basses. That's the amazing world of electronics don't u think?
I do a full repair job on them, meaning internal full electronics and external cleaning and maintenance, trying to keep the original character and shape as much as i can. Even for the simple common 3 prong fix job, i try (if it's possible) to reuse the original prong - cord . I really do care of them and think -amongst others - they are part of our musical history. Never ever a VST or anything similar can be the same with the real thing. But u know they are huge and heavy..

I think it's a good story well told. and a nice outcome. where the hell do you keep finding these organs?

If you are patient and search hard enough you can score some nice finds out there. Local ads and other older musicians mostly.

So far, i am a proud owner of the following monsters: 
Elka Panther/Capri Dual 300, Farfisa Fast 4, Farfisa Fast 5, Farfisa Foyer (rare version one, with 6 voices, not the standard), Farfisa Compact, Philicorda GM 751 full tubes version and two Philicorda's GM 751 transistorized.

As you can understand there is no more free room in the house my 3 year old son to play  :icon_biggrin: Wife warned  "no more combos, just get guitars or basses, they don't take so much room like organs do" mission accomplished: more guitars now  :icon_lol:

Does the ancient spring reverb still works satisfactorily, Sofoklis..??
Yeap absolutelly, it works like a charm! I didn't excpected to, but heh i was lucky this time.
Not like wit my Foyer. I had opened a loong thread here months ago for my other Farfisa the Foyer model (like Farfisa Mini, plus spring rvrb and full tube circuity - 1 rectifier,3 pre's and  2 output tubes), it's a great organ and my most beloved so far, but if you call back in mind this old thread you can see there i finally managed to make the spring reverb functional, but it is a bit weak compared with the loud-full signal in the Compact.
I will be patient, i am sure sometime i will find a Foyer for "Free Pick Up Collection", canibalize it and get the piezo cartridges from inside.
Or maybe pinkjimiphoton
i have a combo compact if ya need parts that needs a home. if interested for a fair price, pm me.
could send me just the piezo cartridges or a substractional power trafo for my Compact who knows  :icon_mrgreen:

So, "no more combos anymore", thank you guys for the discussion, it's a warm place here  8)

What do u think guys ?

I think it's all about the friends we make along the way, and making friends with a transformer shop is as good as it gets!
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« Last Edit: February 21, 2020, 04:42:56 AM by sarakisof »

Rob Strand

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #27 on: February 21, 2020, 04:32:49 PM »
Great story with a happy ending.
The onions are out there for those who want to peel them.

PRR

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #28 on: February 21, 2020, 07:17:39 PM »
> Wife warned  "no more combos, just get guitars or basses, they don't take so much room like organs do" mission accomplished: more guitars now  :icon_lol:

https://www.greatbigstuff.com/products/guitar
http://www.guitarsite.com/news/and_finally/giant_guitar_boat/

Rob Strand

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #29 on: February 21, 2020, 08:22:34 PM »
The biggest guitar I've seen,

https://www.ecorazzi.com/2012/09/10/man-plants-guitar-shaped-forest-to-honor-late-wife/

Saw this by fluke looking out of the window of the plane coming back from Uruguay.
The onions are out there for those who want to peel them.


sarakisof

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #31 on: February 24, 2020, 02:02:38 AM »
> Wife warned  "no more combos, just get guitars or basses, they don't take so much room like organs do" mission accomplished: more guitars now  :icon_lol:

https://www.greatbigstuff.com/products/guitar
http://www.guitarsite.com/news/and_finally/giant_guitar_boat/


 :icon_mrgreen: :icon_mrgreen:

Just for the record, after full recap the beast.


Pass me the Ketchup please ...








Something last: Previous owner had replaced original fuse with another one bigger amps (probably just what he got in hand), so i had to replace it too in first steps.
Maybe stupid question, but schematic mentions just "Fuse 0.5A - 250V.", no fast or slow anywhere. I used a slow blow. Is it OK or i shoud go with fast one?


Pages 4, 7 and 38.
http://www-personal.umich.edu/~damont/FarfisaComboCompactCompleteUserServiceManual.pdf

« Last Edit: February 24, 2020, 02:19:00 AM by sarakisof »

anotherjim

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #32 on: February 24, 2020, 04:10:09 AM »
Generally, low current fuses will be slow-acting to avoid blowing with a switch-on surge that can be expected to be much greater than the service current - like having a lot of caps to charge up.
My name is Fudd. F, f, f, f, Fudd.

anotherjim

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #33 on: February 25, 2020, 02:16:52 PM »
Am I right in thinking that all of the classic divider organs have independent top octave oscillators? How is the tuning stability of those and was there a brand/design that is the most desirable? The reason I ask is that the combo organs in my Nord Electro disappoint me somewhat by being too perfect! I suspect they are only a variation on the Hammond tonewheel modelling which is of course perfectly synchronous.
Additionally, were there any with a master tuning control for all 12 oscillators?


My name is Fudd. F, f, f, f, Fudd.

sarakisof

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #34 on: February 25, 2020, 05:17:26 PM »
Hmm as much as i can say i don't know anyone to use master tuning control for all the 12 oscillos. At least the most well known  ones, brands like Farfisa, Vox, Elka, Gem etc. use top octave independent oscillos and dividers. By the time you open them up to explore the guts it's like pretty common and straight forward process.
How is the tuning stability of those and was there a brand/design that is the most desirable?
Are u in my mind or smthng?  :P i was about to mention here, that compared to my other combo organs, this one tends to behave a bit worse in terms of tuning stability. Don't know why, maybe it's just in my imagination, but i think the A and G# got a bit tiny out of tune since my last tuning a week ago. Maybe my feeling is a bit false, but i will follow silently and looking for any behaviours like that in near future, take tuning neasurements and compare. In my Elka, Fast's and Philicorda's i didn't noticed that, no de-tuning at all since 1 year now.
Whi knows maybe I'm more "sensitive" and care more about my Compact.  :icon_mrgreen:

PRR

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #35 on: February 26, 2020, 12:50:19 AM »
> organs have independent top octave oscillators?

An equal-tempered divider is a VERY complex thing. They "did not exist" for much of e-organ's history. 12 oscillators and knobs was much simpler thus cheaper.

I know when top-octave on a chip was introduced the intervals were only "very tolerable", not perfect. I don't know if this improved as the cost of complexity went down. The top-octave-chip era ended when I was not looking.

R.G. has remarks somewhere on the forum about programming low-price PICs for this duty.

Of course some of the "charm" in many organs is their imperfections. Bach never got all his pipes tuned before they started to drift, especially in days before thermostats. Pianos aren't even in tune with themselves. Tone-wheels have charm in abundance.

amptramp

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #36 on: February 26, 2020, 04:15:04 PM »
The National Semiconductor MOS handbook had several different designs of PMOS top octave generators with different divider ratios.  I don't know who their customers were but these have to show up somewhere.

One idea I had some time ago was a tonewheel type divider connected to a phase locked loop and a phase unlock loop just to keep it from getting properly phase locked so it would sound more like independent oscillators.  The only problem with a phase unlock loop is you never know whether it is going to push the frequency high or low and it has no way to go through the fixed tonewheel frequency.

highwater

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #37 on: February 26, 2020, 11:02:10 PM »
R.G. has remarks somewhere on the forum about programming low-price PICs for this duty.

Tom (electricdruid) has an article about top-octave generation. He turns it a bit sideways, though, using 12 PICs, each generating 10 octaves of one note.
"I had an unfortunate combination of a very high-end medium-size system, with a "low price" phono preamp (external; this was the decade when phono was obsolete)."
 - PRR

anotherjim

Re: Cleaning Power Transformer Bell Out Of Strange Dirt
« Reply #38 on: February 27, 2020, 05:32:57 AM »
Ah, this isn't really a question about TOG's (in fact, I've coded my own TOG in an Atmega328 and in a slow project to build a string machine with it). I was more interested in the apparent preference for old organs with separate oscillators. Is that because of a particular sonic character obtained by carefully tuning to suit? A little beating between intervals can be good, especially if the frequencies wander a little. When you have an error in a TOG, it's stuck and no getting away from it.
For a combo organ, particularly in rock & pop music, the string type voicings are important and to me, that's what sets them apart from a Hammond sound. The strings are essentially high pass filtered square waves. Tuning error between intervals can sound utterly horrid due to the number of high harmonics interacting. This is especially noticed with a TOG instrument and low pass filtering is also required (string machines are typically limited to 5kHz). It also influences playing style - note the preference for fast chord stabs.
My name is Fudd. F, f, f, f, Fudd.